The gdb debugger understands how to parse short versions of the thread
reference string as long as the bytes are paired in sets of two
characters. The kgdb implementation was always sending 8 leading
zeros which could be omitted, and further optimized in the case of
non-negative thread numbers. The negative numbers are used to
reference a specific cpu in the case of kgdb.
An example of the previous i386 stop packet looks like:
T05thread:00000000000003bb;
New stop packet response:
T05thread:03bb;
The previous ThreadInfo response looks like:
m00000000fffffffe,0000000000000001,0000000000000002,0000000000000003,0000000000000004,0000000000000005,0000000000000006,0000000000000007,000000000000000c,0000000000000088,000000000000008a,000000000000008b,000000000000008c,000000000000008d,000000000000008e,00000000000000d4,00000000000000d5,00000000000000dd
New ThreadInfo response:
mfffffffe,01,02,03,04,05,06,07,0c,88,8a,8b,8c,8d,8e,d4,d5,dd
A few bytes saved means better response time when using kgdb over a
serial line.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
When a secondary CPU is being brought up, it is not uncommon for
printk() to be invoked when cpu_online(smp_processor_id()) == 0. The
case that I witnessed personally was on MIPS:
http://lkml.org/lkml/2010/5/30/4
If (can_use_console() == 0), printk() will spool its output to log_buf
and it will be visible in "dmesg", but that output will NOT be echoed to
the console until somebody calls release_console_sem() from a CPU that
is online. Therefore, the boot time messages from the new CPU can get
stuck in "limbo" for a long time, and might suddenly appear on the
screen when a completely unrelated event (e.g. "eth0: link is down")
occurs.
This patch modifies the console code so that any pending messages are
automatically flushed out to the console whenever a CPU hotplug
operation completes successfully or aborts.
The issue was seen on 2.6.34.
Original patch by Kevin Cernekee with cleanups by akpm and additional fixes
by Santosh Shilimkar. This patch superseeds
https://patchwork.linux-mips.org/patch/1357/.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
To: <mingo@elte.hu>
To: <akpm@linux-foundation.org>
To: <simon.kagstrom@netinsight.net>
To: <David.Woodhouse@intel.com>
To: <lethal@linux-sh.org>
Cc: <linux-kernel@vger.kernel.org>
Cc: <linux-mips@linux-mips.org>
Reviewed-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1534/
LKML-Reference: <ede63b5a20af951c755736f035d1e787772d7c28@localhost>
LKML-Reference: <EAF47CD23C76F840A9E7FCE10091EFAB02C5DB6D1F@dbde02.ent.ti.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
On my (32-bit x86) machine, sys_init_module() uses 124 bytes of stack
once load_module() is inlined.
This effectively reverts ffb4ba76 which inlined it due to stack
pressure.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This simply hoists more code out of load_module; we also put the
identification of the extable and dynamic debug table in with the
others in find_module_sections().
We move the taint check to the actual add/remove of the dynamic debug
info: this is certain (find_module_sections is too early).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Yehuda Sadeh <yehuda@hq.newdream.net>
Instead of copying and allocating the args and storing it in
load_info, we can just allocate them right before we need them.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Pass the struct load_info into all the other functions in module
loading. This neatens things and makes them more consistent.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Restore the stub module_remove_modinfo_attrs, remove the now-unused
!CONFIG_SYSFS module_sysfs_init.
Also, rename mod_kobject_remove() to mod_sysfs_teardown() as
it is the logical counterpart to mod_sysfs_setup now.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We change the sysfs functions to take struct load_info, and call
them all in mod_sysfs_setup().
We also clean up the #ifdefs a little.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
layout_and_allocate() does everything up to and including the final
struct module placement inside the allocated module memory. We have
to store the symbol layout information in our struct load_info though.
This avoids the nasty code we had before where 'mod' pointed first
to the version inside the temporary allocation containing the entire
file, then later was moved to point to the real struct module: now
the main code only ever sees the final module address.
(Includes fix for the Tony Luck-found Linus-diagnosed failure path
error).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Andrew had the sole pleasure of tickling this bug in linux-next; when we set
up "info->strtab" it's pointing into the temporary copy of the module. For
most uses that is fine, but kallsyms keeps a pointer around during module
load (inside mod->strtab).
If we oops for some reason inside a module's init function, kallsyms will use
the mod->strtab pointer into the now-freed temporary module copy.
(Later oopses work fine: after init we overwrite mod->strtab to point to a
compacted core-only strtab).
Reported-by: Andrew "Grumpy" Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty "Buggy" Russell <rusty@rustcorp.com.au>
Tested-by: Andrew "Happy" Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Put all the "rewrite and check section headers" in one place. This
adds another iteration over the sections, but it's far clearer. We
iterate once for every find_section() so we already iterate over many
times.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Btw, here's a patch that _looks_ large, but it really pretty trivial, and
sets things up so that it would be way easier to split off pieces of the
module loading.
The reason it looks large is that it creates a "module_info" structure
that contains all the module state that we're building up while loading,
instead of having individual variables for all the indices etc.
So the patch ends up being large, because every "symindex" access instead
becomes "info.index.sym" etc. That may be a few characters longer, but it
then means that we can just pass a pointer to that "info" structure
around. and let all the pieces fill it in very naturally.
As an example of that, the patch also moves the initialization of all
those convenience variables into a "setup_module_info()" function. And at
this point it really does become very natural to start to peel off some of
the error labels and move them into the helper functions - now the
"truncated" case is gone, and is handled inside that setup function
instead.
So maybe you don't like this approach, and it does make the variable
accesses a bit longer, but I don't think unreadably so. And the patch
really does look big and scary, but there really should be absolutely no
semantic changes - most of it was a trivial and mindless rename.
In fact, it was so mindless that I on purpose kept the existing helper
functions looking like this:
- err = check_modinfo(mod, sechdrs, infoindex, versindex);
+ err = check_modinfo(mod, info.sechdrs, info.index.info, info.index.vers);
rather than changing them to just take the "info" pointer. IOW, a second
phase (if you think the approach is ok) would change that calling
convention to just do
err = check_modinfo(mod, &info);
(and same for "layout_sections()", "layout_symtabs()" etc.) Similarly,
while right now it makes things _look_ bigger, with things like this:
versindex = find_sec(hdr, sechdrs, secstrings, "__versions");
becoming
info->index.vers = find_sec(info->hdr, info->sechdrs, info->secstrings, "__versions");
in the new "setup_module_info()" function, that's again just a result of
it being a search-and-replace patch. By using the 'info' pointer, we could
just change the 'find_sec()' interface so that it ends up being
info->index.vers = find_sec(info, "__versions");
instead, and then we'd actually have a shorter and more readable line. So
for a lot of those mindless variable name expansions there's would be room
for separate cleanups.
I didn't move quite everything in there - if we do this to layout_symtabs,
for example, we'd want to move the percpu, symoffs, stroffs, *strmap
variables to be fields in that module_info structure too. But that's a
much smaller patch, I moved just the really core stuff that is currently
being set up and used in various parts.
But even in this rough form, it removes close to 70 lines from that
function (but adds 22 lines overall, of course - the structure definition,
the helper function declarations and call-sites etc etc).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
And now that I'm looking at that call-chain (to see if it would make sense
to use some other more specific lock - doesn't look like it: all the
readers are using RCU and this is the only writer), I also give you this
trivial one-liner. It changes each_symbol() to not put that constant array
on the stack, resulting in changing
movq $C.388.31095, %rsi #, tmp85
subq $376, %rsp #,
movq %rdi, %rbx # fn, fn
leaq -208(%rbp), %rdi #, tmp84
movq %rbx, %rdx # fn,
rep movsl
xorl %esi, %esi #
leaq -208(%rbp), %rdi #, tmp87
movq %r12, %rcx # data,
call each_symbol_in_section.clone.0 #
into
xorl %esi, %esi #
subq $216, %rsp #,
movq %rdi, %rbx # fn, fn
movq $arr.31078, %rdi #,
call each_symbol_in_section.clone.0 #
which is not so much about being obviously shorter and simpler because we
don't unnecessarily copy that constant array around onto the stack, but
also about having a much smaller stack footprint (376 vs 216 bytes - see
the update of 'rsp').
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
1) Extract out the relocation loop into apply_relocations
2) Extract license and version checks into check_module_license_and_versions
3) Extract icache flushing into flush_module_icache
4) Move __obsparm warning into find_module_sections
5) Move license setting into check_modinfo.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Allocate references inside module_unload_init(), clean up inside
module_unload_free().
This version fixed to do allocation before __this_cpu_write, thanks to
bug reports from linux-next from Dave Young <hidave.darkstar@gmail.com>
and Stephen Rothwell <sfr@canb.auug.org.au>.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Here's a second one. It's slightly less trivial - since we now have error
cases - and equally untested so it may well be totally broken. But it also
cleans up a bit more, and avoids one of the goto targets, because the
"move_module()" helper now does both allocations or none.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I'd start from the trivial stuff. There's a fair amount of straight-line
code that just makes the function hard to read just because you have to
page up and down so far. Some of it is trivial to just create a helper
function for.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
No need to clear mod->refptr in module_unload_init(), since
alloc_percpu() already clears allocated chunks.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed unused var)
* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (39 commits)
random: Reorder struct entropy_store to remove padding on 64bits
padata: update API documentation
padata: Remove padata_get_cpumask
crypto: pcrypt - Update pcrypt cpumask according to the padata cpumask notifier
crypto: pcrypt - Rename pcrypt_instance
padata: Pass the padata cpumasks to the cpumask_change_notifier chain
padata: Rearrange set_cpumask functions
padata: Rename padata_alloc functions
crypto: pcrypt - Dont calulate a callback cpu on empty callback cpumask
padata: Check for valid cpumasks
padata: Allocate cpumask dependend recources in any case
padata: Fix cpu index counting
crypto: geode_aes - Convert pci_table entries to PCI_VDEVICE (if PCI_ANY_ID is used)
pcrypt: Added sysfs interface to pcrypt
padata: Added sysfs primitives to padata subsystem
padata: Make two separate cpumasks
padata: update documentation
padata: simplify serialization mechanism
padata: make padata_do_parallel to return zero on success
padata: Handle empty padata cpumasks
...
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1443 commits)
phy/marvell: add 88ec048 support
igb: Program MDICNFG register prior to PHY init
e1000e: correct MAC-PHY interconnect register offset for 82579
hso: Add new product ID
can: Add driver for esd CAN-USB/2 device
l2tp: fix export of header file for userspace
can-raw: Fix skb_orphan_try handling
Revert "net: remove zap_completion_queue"
net: cleanup inclusion
phy/marvell: add 88e1121 interface mode support
u32: negative offset fix
net: Fix a typo from "dev" to "ndev"
igb: Use irq_synchronize per vector when using MSI-X
ixgbevf: fix null pointer dereference due to filter being set for VLAN 0
e1000e: Fix irq_synchronize in MSI-X case
e1000e: register pm_qos request on hardware activation
ip_fragment: fix subtracting PPPOE_SES_HLEN from mtu twice
net: Add getsockopt support for TCP thin-streams
cxgb4: update driver version
cxgb4: add new PCI IDs
...
Manually fix up conflicts in:
- drivers/net/e1000e/netdev.c: due to pm_qos registration
infrastructure changes
- drivers/net/phy/marvell.c: conflict between adding 88ec048 support
and cleaning up the IDs
- drivers/net/wireless/ipw2x00/ipw2100.c: trivial ipw2100_pm_qos_req
conflict (registration change vs marking it static)
Commit 8f92054e7c ("CRED: Fix __task_cred()'s lockdep check and banner
comment") fixed the lockdep checks on __task_cred(). This has shown up
a place in the signalling code where a lock should be held - namely that
check_kill_permission() requires its callers to hold the RCU lock.
Fix group_send_sig_info() to get the RCU read lock around its call to
check_kill_permission().
Without this patch, the following warning can occur:
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
kernel/signal.c:660 invoked rcu_dereference_check() without protection!
...
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6:
PM / Runtime: Add runtime PM statistics (v3)
PM / Runtime: Make runtime_status attribute not debug-only (v. 2)
PM: Do not use dynamically allocated objects in pm_wakeup_event()
PM / Suspend: Fix ordering of calls in suspend error paths
PM / Hibernate: Fix snapshot error code path
PM / Hibernate: Fix hibernation_platform_enter()
pm_qos: Get rid of the allocation in pm_qos_add_request()
pm_qos: Reimplement using plists
plist: Add plist_last
PM: Make it possible to avoid races between wakeup and system sleep
PNPACPI: Add support for remote wakeup
PM: describe kernel policy regarding wakeup defaults (v. 2)
PM / Hibernate: Fix typos in comments in kernel/power/swap.c
Comment in unregister_trace_probe() says probe_lock will be held when it
gets called. However there is a case where it might called without the
probe_lock being held. Also since we are traversing the probe_list and
deleting an element from the probe_list, probe_lock should be held.
This was first pointed in uprobes traceevent review by Frederic
Weisbecker here. (http://lkml.org/lkml/2010/5/12/106)
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100630084548.GA10325@linux.vnet.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
usleep_range is a finer precision implementations of msleep
and is designed to be a drop-in replacement for udelay where
a precise sleep / busy-wait is unnecessary.
Since an easy interface to hrtimers could lead to an undesired
proliferation of interrupts, we provide only a "range" API,
forcing the caller to think about an acceptable tolerance on
both ends and hopefully avoiding introducing another interrupt.
INTRO
As discussed here ( http://lkml.org/lkml/2007/8/3/250 ), msleep(1) is not
precise enough for many drivers (yes, sleep precision is an unfair notion,
but consistently sleeping for ~an order of magnitude greater than requested
is worth fixing). This patch adds a usleep API so that udelay does not have
to be used. Obviously not every udelay can be replaced (those in atomic
contexts or being used for simple bitbanging come to mind), but there are
many, many examples of
mydriver_write(...)
/* Wait for hardware to latch */
udelay(100)
in various drivers where a busy-wait loop is neither beneficial nor
necessary, but msleep simply does not provide enough precision and people
are using a busy-wait loop instead.
CONCERNS FROM THE RFC
Why is udelay a problem / necessary? Most callers of udelay are in device/
driver initialization code, which is serial...
As I see it, there is only benefit to sleeping over a delay; the
notion of "refactoring" areas that use udelay was presented, but
I see usleep as the refactoring. Consider i2c, if the bus is busy,
you need to wait a bit (say 100us) before trying again, your
current options are:
* udelay(100)
* msleep(1) <-- As noted above, actually as high as ~20ms
on some platforms, so not really an option
* Manually set up an hrtimer to try again in 100us (which
is what usleep does anyway...)
People choose the udelay route because it is EASY; we need to
provide a better easy route.
Device / driver / boot code is *currently* serial, but every few
months someone makes noise about parallelizing boot, and IMHO, a
little forward-thinking now is one less thing to worry about
if/when that ever happens
udelay's could be preempted
Sure, but if udelay plans on looping 1000 times, and it gets
preempted on loop 200, whenever it's scheduled again, it is
going to do the next 800 loops.
Is the interruptible case needed?
Probably not, but I see usleep as a very logical parallel to msleep,
so it made sense to include the "full" API. Processors are getting
faster (albeit not as quickly as they are becoming more parallel),
so if someone wanted to be interruptible for a few usecs, why not
let them? If this is a contentious point, I'm happy to remove it.
OTHER THOUGHTS
I believe there is also value in exposing the usleep_range option; it gives
the scheduler a lot more flexibility and allows the programmer to express
his intent much more clearly; it's something I would hope future driver
writers will take advantage of.
To get the results in the NUMBERS section below, I literally s/udelay/usleep
the kernel tree; I had to go in and undo the changes to the USB drivers, but
everything else booted successfully; I find that extremely telling in and
of itself -- many people are using a delay API where a sleep will suit them
just fine.
SOME ATTEMPTS AT NUMBERS
It turns out that calculating quantifiable benefit on this is challenging,
so instead I will simply present the current state of things, and I hope
this to be sufficient:
How many udelay calls are there in 2.6.35-rc5?
udealy(ARG) >= | COUNT
1000 | 319
500 | 414
100 | 1146
20 | 1832
I am working on Android, so that is my focus for this. The following table
is a modified usleep that simply printk's the amount of time requested to
sleep; these tests were run on a kernel with udelay >= 20 --> usleep
"boot" is power-on to lock screen
"power collapse" is when the power button is pushed and the device suspends
"resume" is when the power button is pushed and the lock screen is displayed
(no touchscreen events or anything, just turning on the display)
"use device" is from the unlock swipe to clicking around a bit; there is no
sd card in this phone, so fail loading music, video, camera
ACTION | TOTAL NUMBER OF USLEEP CALLS | NET TIME (us)
boot | 22 | 1250
power-collapse | 9 | 1200
resume | 5 | 500
use device | 59 | 7700
The most interesting category to me is the "use device" field; 7700us of
busy-wait time that could be put towards better responsiveness, or at the
least less power usage.
Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
Cc: apw@canonical.com
Cc: corbet@lwn.net
Cc: arjan@linux.intel.com
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In some cases (for instance with kernel threads) it may be desireable to
use on-stack deferrable timers to get their power saving benefits. Add
interfaces to support this for the IPS driver.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Historically, Linux has tried to make the regular timer tick on the
various CPUs not happen at the same time, to avoid contention on
xtime_lock.
Nowadays, with the tickless kernel, this contention no longer happens
since time keeping and updating are done differently. In addition,
this skew is actually hurting power consumption in a measurable way on
many-core systems.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100727210210.58d3118c@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We use synchronize_sched() to ensure a tracepoint won't be called
while/after we release the perf buffers it references.
But the tracepoint API has its own API for that:
tracepoint_synchronize_unregister(). Use it instead as it's
self-explanatory and eases maintainance.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Mark init_workqueues() as early_initcall() and thus it will be initialized
before smp bringup. init_workqueues() registers for the hotcpu notifier
and thus it should cope with the processors that are brought online after
the workqueues are initialized.
x86 smp bringup code uses workqueues and uses a workaround for the
cold boot process (as the workqueues are initialized post smp_init()).
Marking init_workqueues() as early_initcall() will pave the way for
cleaning up this code.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
for_each_*cwq_cpu() are similar to regular CPU iterators except that
it also considers the pseudo CPU number used for unbound workqueues.
Explain them.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
A function that copies the padata cpumasks to a user buffer
is a bit error prone. The cpumask can change any time so we
can't be sure to have the right cpumask when using this function.
A user who is interested in the padata cpumasks should register
to the padata cpumask notifier chain instead. Users of
padata_get_cpumask are already updated, so we can remove it.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
We pass a pointer to the new padata cpumasks to the cpumask_change_notifier
chain. So users can access the cpumasks without the need of an extra
padata_get_cpumask function.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
padata_set_cpumask needs to be protected by a lock. We make
__padata_set_cpumasks unlocked and static. So this function
can be used by the exported and locked padata_set_cpumask and
padata_set_cpumasks functions.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
We rename padata_alloc to padata_alloc_possible because this
function allocates a padata_instance and uses the cpu_possible
mask for parallel and serial workers. Also we rename __padata_alloc
to padata_alloc to avoid to export underlined functions. Underlined
functions are considered to be private to padata. Users are updated
accordingly.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
It's possible for get_task_cred() as it currently stands to 'corrupt' a set of
credentials by incrementing their usage count after their replacement by the
task being accessed.
What happens is that get_task_cred() can race with commit_creds():
TASK_1 TASK_2 RCU_CLEANER
-->get_task_cred(TASK_2)
rcu_read_lock()
__cred = __task_cred(TASK_2)
-->commit_creds()
old_cred = TASK_2->real_cred
TASK_2->real_cred = ...
put_cred(old_cred)
call_rcu(old_cred)
[__cred->usage == 0]
get_cred(__cred)
[__cred->usage == 1]
rcu_read_unlock()
-->put_cred_rcu()
[__cred->usage == 1]
panic()
However, since a tasks credentials are generally not changed very often, we can
reasonably make use of a loop involving reading the creds pointer and using
atomic_inc_not_zero() to attempt to increment it if it hasn't already hit zero.
If successful, we can safely return the credentials in the knowledge that, even
if the task we're accessing has released them, they haven't gone to the RCU
cleanup code.
We then change task_state() in procfs to use get_task_cred() rather than
calling get_cred() on the result of __task_cred(), as that suffers from the
same problem.
Without this change, a BUG_ON in __put_cred() or in put_cred_rcu() can be
tripped when it is noticed that the usage count is not zero as it ought to be,
for example:
kernel BUG at kernel/cred.c:168!
invalid opcode: 0000 [#1] SMP
last sysfs file: /sys/kernel/mm/ksm/run
CPU 0
Pid: 2436, comm: master Not tainted 2.6.33.3-85.fc13.x86_64 #1 0HR330/OptiPlex
745
RIP: 0010:[<ffffffff81069881>] [<ffffffff81069881>] __put_cred+0xc/0x45
RSP: 0018:ffff88019e7e9eb8 EFLAGS: 00010202
RAX: 0000000000000001 RBX: ffff880161514480 RCX: 00000000ffffffff
RDX: 00000000ffffffff RSI: ffff880140c690c0 RDI: ffff880140c690c0
RBP: ffff88019e7e9eb8 R08: 00000000000000d0 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000040 R12: ffff880140c690c0
R13: ffff88019e77aea0 R14: 00007fff336b0a5c R15: 0000000000000001
FS: 00007f12f50d97c0(0000) GS:ffff880007400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8f461bc000 CR3: 00000001b26ce000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process master (pid: 2436, threadinfo ffff88019e7e8000, task ffff88019e77aea0)
Stack:
ffff88019e7e9ec8 ffffffff810698cd ffff88019e7e9ef8 ffffffff81069b45
<0> ffff880161514180 ffff880161514480 ffff880161514180 0000000000000000
<0> ffff88019e7e9f28 ffffffff8106aace 0000000000000001 0000000000000246
Call Trace:
[<ffffffff810698cd>] put_cred+0x13/0x15
[<ffffffff81069b45>] commit_creds+0x16b/0x175
[<ffffffff8106aace>] set_current_groups+0x47/0x4e
[<ffffffff8106ac89>] sys_setgroups+0xf6/0x105
[<ffffffff81009b02>] system_call_fastpath+0x16/0x1b
Code: 48 8d 71 ff e8 7e 4e 15 00 85 c0 78 0b 8b 75 ec 48 89 df e8 ef 4a 15 00
48 83 c4 18 5b c9 c3 55 8b 07 8b 07 48 89 e5 85 c0 74 04 <0f> 0b eb fe 65 48 8b
04 25 00 cc 00 00 48 3b b8 58 04 00 00 75
RIP [<ffffffff81069881>] __put_cred+0xc/0x45
RSP <ffff88019e7e9eb8>
---[ end trace df391256a100ebdd ]---
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A small number of users of IRQF_TIMER are using it for the implied no
suspend behaviour on interrupts which are not timer interrupts.
Therefore add a new IRQF_NO_SUSPEND flag, rename IRQF_TIMER to
__IRQF_TIMER and redefine IRQF_TIMER in terms of these new flags.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: xen-devel@lists.xensource.com
Cc: linux-input@vger.kernel.org
Cc: linuxppc-dev@ozlabs.org
Cc: devicetree-discuss@lists.ozlabs.org
LKML-Reference: <1280398595-29708-1-git-send-email-ian.campbell@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
fanotify currently, when given a vfsmount_mark will look up (if it exists)
the corresponding inode mark. This patch drops that lookup and uses the
mark provided.
Signed-off-by: Eric Paris <eparis@redhat.com>
should_send_event() and handle_event() will both need to look up the inode
event if they get a vfsmount event. Lets just pass both at the same time
since we have them both after walking the lists in lockstep.
Signed-off-by: Eric Paris <eparis@redhat.com>
group->mask is now useless. It was originally a shortcut for fsnotify to
save on performance. These checks are now redundant, so we remove them.
Signed-off-by: Eric Paris <eparis@redhat.com>
The change to use srcu and walk the object list rather than the global
fsnotify_group list means that should_send_event is no longer needed for a
number of groups and can be simplified for others. Do that.
Signed-off-by: Eric Paris <eparis@redhat.com>
audit now gets a mark in the should_send_event and handle_event
functions. Rather than look up the mark themselves audit should just use
the mark it was handed.
Signed-off-by: Eric Paris <eparis@redhat.com>
With the change of fsnotify to use srcu walking the marks list instead of
walking the global groups list we now know the mark in question. The code can
send the mark to the group's handling functions and the groups won't have to
find those marks themselves.
Signed-off-by: Eric Paris <eparis@redhat.com>
Al explains that calling dentry_open() with a mnt/dentry pair is only
garunteed to be safe if they are already used in an open struct file. To
make sure this is the case don't store and use a struct path in fsnotify,
always use a struct file.
Signed-off-by: Eric Paris <eparis@redhat.com>
Extern declarations in sysctl.c should be move to their own head file, and
then include them in relavant .c files.
Move inotify_table extern declaration to linux/inotify.h
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Paris <eparis@redhat.com>
Move dir_notify_enable declaration to where it belongs -- dnotify.h .
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
currently all marking is done by functions in inode-mark.c. Some of this
is pretty generic and should be instead done in a generic function and we
should only put the inode specific code in inode-mark.c
Signed-off-by: Eric Paris <eparis@redhat.com>
This patch simply declares the new sys_fanotify_mark syscall
int fanotify_mark(int fanotify_fd, unsigned int flags, u64_mask,
int dfd const char *pathname)
Signed-off-by: Eric Paris <eparis@redhat.com>
This patch defines a new syscall fanotify_init() of the form:
int sys_fanotify_init(unsigned int flags, unsigned int event_f_flags,
unsigned int priority)
This syscall is used to create and fanotify group. This is very similar to
the inotify_init() syscall.
Signed-off-by: Eric Paris <eparis@redhat.com>
All callers to fsnotify_find_mark_entry() except one take and
release inode->i_lock around the call. Take the lock inside
fsnotify_find_mark_entry() instead.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
The addition of marks on vfs mounts will be simplified if the inode
specific parts of a mark and the vfsmnt specific parts of a mark are
actually in a union so naming can be easy. This patch just implements the
inode struct and the union.
Signed-off-by: Eric Paris <eparis@redhat.com>
To ensure that a group will not duplicate events when it receives it based
on the vfsmount and the inode should_send_event test we should distinguish
those two cases. We pass a vfsmount to this function so groups can make
their own determinations.
Signed-off-by: Eric Paris <eparis@redhat.com>
Currently the audit watch group always sets a mask equal to all events it
might care about. We instead should only set the group mask if we are
actually watching inodes. This should be a perf win when audit watches are
compiled in.
Signed-off-by: Eric Paris <eparis@redhat.com>
fsnotify_obtain_group was intended to be able to find an already existing
group. Nothing uses that functionality. This just renames it to
fsnotify_alloc_group so it is clear what it is doing.
Signed-off-by: Eric Paris <eparis@redhat.com>
The original fsnotify interface has a group-num which was intended to be
able to find a group after it was added. I no longer think this is a
necessary thing to do and so we remove the group_num.
Signed-off-by: Eric Paris <eparis@redhat.com>
fanotify is going to need to look at file->private_data to know if an event
should be sent or not. This passes the data (which might be a file,
dentry, inode, or none) to the should_send function calls so fanotify can
get that information when available
Signed-off-by: Eric Paris <eparis@redhat.com>
fanotify is only interested in event types which contain enough information
to open the original file in the context of the fanotify listener. Since
fanotify may not want to send events if that data isn't present we pass
the data type to the should_send_event function call so fanotify can express
its lack of interest.
Signed-off-by: Eric Paris <eparis@redhat.com>
Audit watch init and fsnotify init both use subsys_initcall() but since the
audit watch code is linked in before the fsnotify code the audit watch code
would be using the fsnotify srcu struct before it was initialized. This
patch fixes that problem by moving audit watch init to device_initcall() so
it happens after fsnotify is ready.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Eric Paris <eparis@redhat.com>
Tested-by : Sachin Sant <sachinp@in.ibm.com>
Audit watch should depend on CONFIG_AUDIT_SYSCALL and should select
FSNOTIFY. This splits the spagetti like mixing of audit_watch and
audit_filter code so they can be configured seperately.
Signed-off-by: Eric Paris <eparis@redhat.com>
Simply switch audit_trees from using inotify to using fsnotify for it's
inode pinning and disappearing act information.
Signed-off-by: Eric Paris <eparis@redhat.com>
This patch allows a task to add a second fsnotify mark to an inode for the
same group. This mark will be added to the end of the inode's list and
this will never be found by the stand fsnotify_find_mark() function. This
is useful if a user wants to add a new mark before removing the old one.
Signed-off-by: Eric Paris <eparis@redhat.com>
deleting audit watch rules is not currently done under audit_filter_mutex.
It was done this way because we could not hold the mutex during inotify
manipulation. Since we are using fsnotify we don't need to do the extra
get/put pair nor do we need the private list on which to store the parents
while they are about to be freed.
Signed-off-by: Eric Paris <eparis@redhat.com>
fsnotify can handle mutexes to be held across all fsnotify operations since
it deals strickly in spinlocks. This can simplify and reduce some of the
audit_filter_mutex taking and dropping.
Signed-off-by: Eric Paris <eparis@redhat.com>
Audit currently uses inotify to pin inodes in core and to detect when
watched inodes are deleted or unmounted. This patch uses fsnotify instead
of inotify.
Signed-off-by: Eric Paris <eparis@redhat.com>
No real changes, just cleanup to the audit_watch split patch which we done
with minimal code changes for easy review. Now fix interfaces to make
things work better.
Signed-off-by: Eric Paris <eparis@redhat.com>
Add a new kernel API to attach a task to current task's cgroup
in all the active hierarchies.
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paul Menage <menage@google.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
The command
echo "file ec.c +p" >/sys/kernel/debug/dynamic_debug/control
causes an oops.
Move the call to ddebug_remove_module() down into free_module(). In this
way it should be called from all error paths. Currently, we are missing
the remove if the module init routine fails.
Signed-off-by: Jason Baron <jbaron@redhat.com>
Reported-by: Thomas Renninger <trenn@suse.de>
Tested-by: Thomas Renninger <trenn@suse.de>
Cc: <stable@kernel.org> [2.6.32+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To properly handle clocksources that change frequencies
at the clocksource->enable() point, this patch adds
a method that will update the clocksource's mult/shift and
max_idle_ns values.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-12-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch makes xtime and wall_to_monotonic static, as planned in
Documentation/feature-removal-schedule.txt. This will allow for
further cleanups to the timekeeping core.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-10-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Provides an accessor function to replace hrtimer.c's
direct access of wall_to_monotonic.
This will allow wall_to_monotonic to be made static as
planned in Documentation/feature-removal-schedule.txt
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-9-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
update_vsyscall() did not provide the wall_to_monotoinc offset,
so arch specific implementations tend to reference wall_to_monotonic
directly. This limits future cleanups in the timekeeping core, so
this patch fixes the update_vsyscall interface to provide
wall_to_monotonic, allowing wall_to_monotonic to be made static
as planned in Documentation/feature-removal-schedule.txt
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Tony Luck <tony.luck@intel.com>
LKML-Reference: <1279068988-21864-7-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that all arches have been converted over to use generic time via
clocksources or arch_gettimeoffset(), we can remove the GENERIC_TIME
config option and simplify the generic code.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-4-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
After accidentally misusing timespec_add_safe, I wanted to make sure
we don't accidently trip over that issue again, so I created a simple
timespec_add() function which we can use to replace the instances
of timespec_add_safe() that don't want the overflow detection.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-3-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that we allow to change the cpumasks from userspace, we have
to check for valid cpumasks in padata_do_parallel. This patch adds
the necessary check. This fixes a division by zero crash if the
parallel cpumask contains no active cpu.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The cpumask separation work assumes the cpumask dependend recources
present regardless of valid or invalid cpumasks. With this patch
we allocate the cpumask dependend recources in any case. This fixes
two NULL pointer dereference crashes in padata_replace and in
padata_get_cpumask.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The counting of the cpu index got lost with a recent commit.
This patch restores it. This fixes a hang of the parallel worker
threads on cpu hotplug.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
According to Oleg Nesterov:
We can move copy_to_user(created_timer_id) down after
"if (timer_event_spec)" block too. (but before CLOCK_DISPATCH(),
of course).
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
usleep[_range] are finer precision implementations of msleep
and are designed to be drop-in replacements for udelay where
a precise sleep / busy-wait is unnecessary. They also allow
an easy interface to specify slack when a precise (ish)
wakeup is unnecessary to help minimize wakeups
Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
Cc: akinobu.mita@gmail.com
Cc: sboyd@codeaurora.org
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <4C44CDD2.1070708@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Steal some text from 6e453a6751 "Add support for deferrable timers". A
reader shouldn't have to dig through the git logs for the basic
description of a deferrable timer.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: johnstul@us.ibm.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Once a work starts execution, its data contains the cpu number it was
on instead of pointing to cwq. This is added by commit 7a22ad75
(workqueue: carry cpu number in work data once execution starts) to
reliably determine the work was last on even if the workqueue itself
was destroyed inbetween.
Whether data points to a cwq or contains a cpu number was
distinguished by comparing the value against PAGE_OFFSET. The
assumption was that a cpu number should be below PAGE_OFFSET while a
pointer to cwq should be above it. However, on architectures which
use separate address spaces for user and kernel spaces, this doesn't
hold as PAGE_OFFSET is zero.
Fix it by using an explicit flag, WORK_STRUCT_CWQ, to mark what the
data field contains. If the flag is set, it's pointing to a cwq;
otherwise, it contains a cpu number.
Reported on s390 and microblaze during linux-next testing.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sachin Sant <sachinp@in.ibm.com>
Reported-by: Michal Simek <michal.simek@petalogix.com>
Reported-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Tested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Tested-by: Michal Simek <monstr@monstr.eu>
We need to add one to the strlen() return because of the NULL
character. The type->name here generally comes from the kernel and I
don't think any of them come close to being MAX_TRACER_SIZE (100)
characters long so this is basically a cleanup.
Signed-off-by: Dan Carpenter <error27@gmail.com>
LKML-Reference: <20100710100644.GV19184@bicker>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The kdb code should not toggle the sysrq state in case an end user
wants to try and resume the normal kernel execution.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Immediately following an exit from the kdb shell the kgdb_connected
variable should be set to zero, unless there are breakpoints planted.
If the kgdb_connected variable is not zeroed out with kdb, it is
impossible to turn off kdb.
This patch is merely a work around for now, the real fix will check
for the breakpoints.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
In the process of merging kdb to the mainline, the kdb lsmod command
stopped printing the base load address of kernel modules. This is
needed for using kdb in conjunction with external tools such as gdb.
Simply restore the functionality by adding a kdb_printf for the base
load address of the kernel modules.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The gdbserial protocol handler should return an empty packet instead
of an error string when ever it responds to a command it does not
implement.
The problem cases come from a debugger client sending
qTBuffer, qTStatus, qSearch, qSupported.
The incorrect response from the gdbstub leads the debugger clients to
not function correctly. Recent versions of gdb will not detach correctly as a result of this behavior.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Without this patch the "ll" linked-list traversal command won't
terminate when you hit q/Q.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The sched_child_runs_first value in /proc/sched_debug is
currently displayed using a macro meant to split ns time values.
This patch uses the correct macro to display it as a plain
decimal value.
Signed-off-by: Josh Hunt <johunt@akamai.com>
Cc: peterz@infradead.org
Cc: juhlenko@akamai.com
Cc: efault@gmx.de
LKML-Reference: <1279567876-25418-1-git-send-email-johunt@akamai.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Documentation/trace/ftrace.txt says
buffer_size_kb:
This sets or displays the number of kilobytes each CPU
buffer can hold. The tracer buffers are the same size
for each CPU. The displayed number is the size of the
CPU buffer and not total size of all buffers. The
trace buffers are allocated in pages (blocks of memory
that the kernel uses for allocation, usually 4 KB in size).
If the last page allocated has room for more bytes
than requested, the rest of the page will be used,
making the actual allocation bigger than requested.
( Note, the size may not be a multiple of the page size
due to buffer management overhead. )
This can only be updated when the current_tracer
is set to "nop".
But it's incorrect. currently total memory consumption is
'buffer_size_kb x CPUs x 2'.
Why two times difference is there? because ftrace implicitly allocate
the buffer for max latency too.
That makes sad result when admin want to use large buffer. (If admin
want full logging and makes detail analysis). example, If admin
have 24 CPUs machine and write 200MB to buffer_size_kb, the system
consume ~10GB memory (200MB x 24 x 2). umm.. 5GB memory waste is
usually unacceptable.
Fortunatelly, almost all users don't use max latency feature.
The max latency buffer can be disabled easily.
This patch shrink buffer size of the max latency buffer if
unnecessary.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20100701104554.DA2D.A69D9226@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
__print_flags() and __print_symbolic() use percpu trace_seq:
1) Its memory is allocated at compile time, it wastes memory if we don't use tracing.
2) It is percpu data and it wastes more memory for multi-cpus system.
3) It disables preemption when it executes its core routine
"trace_seq_printf(s, "%s: ", #call);" and introduces latency.
So we move this trace_seq to struct trace_iterator.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4C078350.7090106@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Reorder structure to remove 8 bytes of padding on 64 bit builds.
This shrinks the size to 128 bytes so allowing allocation from a smaller
slab & needed one fewer cache lines.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
LKML-Reference: <1269516456.2054.8.camel@localhost>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
We found that even enabling a single trace event that will rarely be
triggered can add big overhead to context switch.
(lmbench context switch test)
-------------------------------------------------
2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
------ ------ ------ ------ ------ ------- -------
2.19 2.3 2.21 2.56 2.13 2.54 2.07
2.39 2.51 2.35 2.75 2.27 2.81 2.24
The overhead is 6% ~ 11%.
It's because when a trace event is enabled 3 tracepoints (sched_switch,
sched_wakeup, sched_wakeup_new) will be activated to map pid to cmdname.
We'd like to avoid this overhead, so add a trace option '(no)record-cmd'
to allow to disable cmdline recording.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4C2D57F4.2050204@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Convert a few calls from kfree_skb to consume_skb
Noticed while I was working on dropwatch that I was detecting lots of internal
skb drops in several places. While some are legitimate, several were not,
freeing skbs that were at the end of their life, rather than being discarded due
to an error. This patch converts those calls sites from using kfree_skb to
consume_skb, which quiets the in-kernel drop_monitor code from detecting them as
drops. Tested successfully by myself
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All cpumasks are assumed to have cpu 0 permanently set on UP, so it
can't be used to signify whether there's something to be done for the
CPU. workqueue was using cpumask to track which CPU requested rescuer
assistance and this led rescuer thread to think there always are
pending mayday requests on UP, which resulted in infinite busy loops.
This patch fixes the problem by introducing mayday_mask_t and
associated helpers which wrap cpumask on SMP and emulates its behavior
using bitops and unsigned long on UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
The default for llseek will change to no_llseek,
so the tracing debugfs files need to add explicit
.llseek assignments. Since we're dealing with regular
files from a VFS perspective, use generic_file_llseek.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John Kacur <jkacur@redhat.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <1278538820-1392-10-git-send-email-arnd@arndb.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Special traces type was only used by sysprof. Lets remove it now
that sysprof ftrace plugin has been dropped.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Soeren Sandmann <sandmann@daimi.au.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
The sysprof ftrace plugin doesn't seem to be seriously used
somewhere. There is a branch in the sysprof tree that makes
an interface to it, but the real sysprof tool uses either its
own module or perf events.
Drop the sysprof ftrace plugin then, as it's mostly useless.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Soeren Sandmann <sandmann@daimi.au.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Commit f3421797 (workqueue: implement unbound workqueue) incorrectly
tested CONFIG_SMP as part of a C expression in alloc/free_cwqs(). As
CONFIG_SMP is not defined in UP, this breaks build. Fix it by using
Found during linux-next build test.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
With commits 08677214 and 59be5a8e, alloc_bootmem()/free_bootmem() and
friends use the early_res functions for memory management when
NO_BOOTMEM is enabled. This patch adds the kmemleak calls in the
corresponding code paths for bootmem allocations.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: stable@kernel.org
pavel@suse.cz no longer works, replace it with working address.
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Added sysfs primitives to padata subsystem. Now API user may
embedded kobject each padata instance contains into any sysfs
hierarchy. For now padata sysfs interface provides only
two objects:
serial_cpumask [RW] - cpumask for serial workers
parallel_cpumask [RW] - cpumask for parallel workers
Signed-off-by: Dan Kruchinin <dkruchinin@acm.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The aim of this patch is to make two separate cpumasks
for padata parallel and serial workers respectively.
It allows user to make more thin and sophisticated configurations
of padata framework. For example user may bind parallel and serial workers to non-intersecting
CPU groups to gain better performance. Also each padata instance has notifiers chain for its
cpumasks now. If either parallel or serial or both masks were changed all
interested subsystems will get notification about that. It's especially useful
if padata user uses algorithm for callback CPU selection according to serial cpumask.
Signed-off-by: Dan Kruchinin <dkruchinin@acm.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The ACPI suspend code calls suspend_nvs_free() at a wrong place,
which may lead to a memory leak if there's an error executing
acpi_pm_prepare(), because acpi_pm_finish() will not be called in
that case. However, the root cause of this problem is the
apparently confusing ordering of calls in suspend error paths that
needs to be fixed.
In addition to that, fix a typo in a label name in suspend.c.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Len Brown <len.brown@intel.com>
There is an inconsistency between hibernation_platform_enter()
and hibernation_snapshot(), because the latter calls
hibernation_ops->end() after failing hibernation_ops->begin(), while
the former doesn't do that. Make hibernation_snapshot() behave in
the same way as hibernation_platform_enter() in that respect.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Len Brown <len.brown@intel.com>
The hibernation_platform_enter() function calls dpm_suspend_noirq()
instead of dpm_resume_noirq() by mistake. Fix this.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Len Brown <len.brown@intel.com>
All current users of pm_qos_add_request() have the ability to supply
the memory required by the pm_qos routines, so make them do this and
eliminate the kmalloc() with pm_qos_add_request(). This has the
double benefit of making the call never fail and allowing it to be
called from atomic context.
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: mark gross <markgross@thegnar.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
A lot of the pm_qos extremal value handling is really duplicating what a
priority ordered list does, just in a less efficient fashion. Simply
redoing the implementation in terms of a plist gets rid of a lot of this
junk (although there are several other strange things that could do with
tidying up, like pm_qos_request_list has to carry the pm_qos_class with
every node, simply because it doesn't get passed in to
pm_qos_update_request even though every caller knows full well what
parameter it's updating).
I think this redo is a win independent of android, so we should do
something like this now.
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: mark gross <markgross@thegnar.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
One of the arguments during the suspend blockers discussion was that
the mainline kernel didn't contain any mechanisms making it possible
to avoid races between wakeup and system suspend.
Generally, there are two problems in that area. First, if a wakeup
event occurs exactly when /sys/power/state is being written to, it
may be delivered to user space right before the freezer kicks in, so
the user space consumer of the event may not be able to process it
before the system is suspended. Second, if a wakeup event occurs
after user space has been frozen, it is not generally guaranteed that
the ongoing transition of the system into a sleep state will be
aborted.
To address these issues introduce a new global sysfs attribute,
/sys/power/wakeup_count, associated with a running counter of wakeup
events and three helper functions, pm_stay_awake(), pm_relax(), and
pm_wakeup_event(), that may be used by kernel subsystems to control
the behavior of this attribute and to request the PM core to abort
system transitions into a sleep state already in progress.
The /sys/power/wakeup_count file may be read from or written to by
user space. Reads will always succeed (unless interrupted by a
signal) and return the current value of the wakeup events counter.
Writes, however, will only succeed if the written number is equal to
the current value of the wakeup events counter. If a write is
successful, it will cause the kernel to save the current value of the
wakeup events counter and to abort the subsequent system transition
into a sleep state if any wakeup events are reported after the write
has returned.
[The assumption is that before writing to /sys/power/state user space
will first read from /sys/power/wakeup_count. Next, user space
consumers of wakeup events will have a chance to acknowledge or
veto the upcoming system transition to a sleep state. Finally, if
the transition is allowed to proceed, /sys/power/wakeup_count will
be written to and if that succeeds, /sys/power/state will be written
to as well. Still, if any wakeup events are reported to the PM core
by kernel subsystems after that point, the transition will be
aborted.]
Additionally, put a wakeup events counter into struct dev_pm_info and
make these per-device wakeup event counters available via sysfs,
so that it's possible to check the activity of various wakeup event
sources within the kernel.
To illustrate how subsystems can use pm_wakeup_event(), make the
low-level PCI runtime PM wakeup-handling code use it.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: markgross <markgross@thegnar.org>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
There are a few typos in kernel/power/swap.c. Fix them.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
As of commit dcce284 ("mm: Extend gfp masking to the page
allocator") and commit 7e85ee0 ("slab,slub: don't enable
interrupts during early boot"), the slab allocator makes
sure we don't attempt to sleep during boot.
Therefore, remove bootmem special cases from the scheduler
and use plain GFP_KERNEL instead.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1279225102-2572-1-git-send-email-penberg@cs.helsinki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Norbert reported that nohz_ratelimit() causes his laptop to burn about
4W (40%) extra. For now back out the change and see if we can adjust
the power management code to make better decisions.
Reported-by: Norbert Preining <preining@logic.at>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently we update cpu_power() too often, update_group_power() only
updates the local group's cpu_power but it gets called for all groups.
Furthermore, CPU_NEWLY_IDLE invocations will result in all cpus
calling it, even though a slow update of cpu_power is sufficient.
Therefore move the update under 'idle != CPU_NEWLY_IDLE &&
local_group' to reduce superfluous invocations.
Reported-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1278612989.1900.176.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Suresh spotted that we don't update the rq->clock in the nohz
load-balancer path.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1278626014.2834.74.camel@sbs-t61.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds the code to support the sys_prlimit64 syscall which
modifies-and-returns the rlim values of a selected process atomically.
The first parameter, pid, being 0 means current process.
Unlike the current implementation, it is a generic interface,
architecture indepentent so that we needn't handle compat stuff
anymore. In the future, after glibc start to use this we can deprecate
sys_setrlimit and sys_getrlimit in favor to clean up the code finally.
It also adds a possibility of changing limits of other processes. We
check the user's permissions to do that and if it succeeds, the new
limits are propagated online. This is good for large scale
applications such as SAP or databases where administrators need to
change limits time by time (e.g. on crashes increase core size). And
it is unacceptable to restart the service.
For safety, all rlim users now either use accessors or doesn't need
them due to
- locking
- the fact a process was just forked and nobody else knows about it
yet (and nobody can't thus read/write limits)
hence it is safe to modify limits now.
The limitation is that we currently stay at ulong internal
representation. So the rlim64_is_infinity check is used where value is
compared against ULONG_MAX on 32-bit which is the maximum value there.
And since internally the limits are held in struct rlimit, converters
which are used before and after do_prlimit call in sys_prlimit64 are
introduced.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
After we added more generic do_prlimit, switch sys_getrlimit to that.
Also switch compat handling, so we can get rid of ugly __user casts
and avoid setting process' address limit to kernel data and back.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
It now allows also reading of limits. I.e. all read and writes will
later use this function.
It takes two parameters, new and old limits which can be both NULL.
If new is non-NULL, the value in it is set to rlimits.
If old is non-NULL, current rlimits are stored there.
If both are non-NULL, old are stored prior to setting the new ones,
atomically.
(Similar to sigaction.)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Do security_task_setrlimit under task_lock. Other tasks may change
limits under our hands while we are checking limits inside the
function. From now on, they can't.
Note that all the security work is done under a spinlock here now.
Security hooks count with that, they are called from interrupt context
(like security_task_kill) and with spinlocks already held (e.g.
capable->security_capable).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: James Morris <jmorris@namei.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Add locking to allow setrlimit accept task parameter other than
current.
Namely, lock tasklist_lock for read and check whether the task
structure has sighand non-null. Do all the signal processing under
that lock still held.
There are some points:
1) security_task_setrlimit is now called with that lock held. This is
not new, many security_* functions are called with this lock held
already so it doesn't harm (all this security_* stuff does almost
the same).
2) task->sighand->siglock (in update_rlimit_cpu) is nested in
tasklist_lock. This dependence is already existing.
3) tsk->alloc_lock is nested in tasklist_lock. This is OK too, already
existing dependence.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Create do_setrlimit from sys_setrlimit and declare do_setrlimit
in the resource header. This is the first phase to have generic
do_prlimit which allows to be called from read, write and compat
rlimits code.
The new do_setrlimit also accepts a task pointer to change the limits
of. Currently, it cannot be other than current, but this will change
with locking later.
Also pass tsk->group_leader to security_task_setrlimit to check
whether current is allowed to change rlimits of the process and not
its arbitrary thread because it makes more sense given that rlimit are
per process and not per-thread.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Mostly preparation for Jiri's changes, but probably makes sense anyway.
sys_setrlimit() checks new_rlim.rlim_max <= old_rlim->rlim_max, but when
it takes task_lock() old_rlim->rlim_max can be already lowered. Move this
check under task_lock().
Currently this is not important, we can only race with our sub-thread,
this means the application is stupid. But when we change the code to allow
the update of !current task's limits, it becomes important to make sure
->rlim_max can be lowered "reliably" even if we race with the application
doing sys_setrlimit().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Add task_struct as a parameter to update_rlimit_cpu to be able to set
rlimit_cpu of different task than current.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: James Morris <jmorris@namei.org>
Add task_struct to task_setrlimit of security_operations to be able to set
rlimit of task other than current.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
The ksym (breakpoint) ftrace plugin has been superseded by perf
tools that are much more poweful to use the cpu breakpoints.
This tracer doesn't bring more feature. It has been deprecated
for a while now, lets remove it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
We count the number of processed objects on a percpu basis,
so we need to go through all the percpu reorder queues to calculate
the sequence number of the next object that needs serialization.
This patch changes this to count the number of processed objects
global. So we can calculate the sequence number and the percpu
reorder queue of the next object that needs serialization without
searching through the percpu reorder queues. This avoids some
accesses to memory of foreign cpus.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
To return -EINPROGRESS on success in padata_do_parallel was
considered to be odd. This patch changes this to return zero
on success. Also the only user of padata, pcrypt is adapted to
convert a return of zero to -EINPROGRESS within the crypto layer.
This also removes the pcrypt fallback if padata_do_parallel
was called on a not running padata instance as we can't handle it
anymore. This fallback was unused, so it's save to remove it.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch fixes a bug when the padata cpumask does not
intersect with the active cpumask. In this case we get a
division by zero in padata_alloc_pd and we end up with a
useless padata instance. Padata can end up with an empty
cpumask for two reasons:
1. A user removed the last cpu that belongs to the padata
cpumask and the active cpumask.
2. The last cpu that belongs to the padata cpumask and the
active cpumask goes offline.
We introduce a function padata_validate_cpumask to check if the padata
cpumask does intersect with the active cpumask. If the cpumasks do not
intersect we mark the instance as invalid, so it can't be used. We do not
allocate the cpumask dependend recources in this case. This fixes the
division by zero and keeps the padate instance in a consistent state.
It's not possible to trigger this bug by now because the only padata user,
pcrypt uses always the possible cpumask.
Reported-by: Dan Kruchinin <dkruchinin@acm.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch makes padata_stop to block until the padata
instance is unused. Also we split padata_stop to a locked
and a unlocked version. This is in preparation to be able
to change the cpumask after a call to patata stop.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch introduces the PADATA_INVALID flag which is
checked on padata start. This will be used to mark a padata
instance as invalid, if the padata cpumask does not intersect
with the active cpumask. we change padata_start to return an
error if the PADATA_INVALID is set. Also we adapt the only
padata user, pcrypt to this change.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
maybe_create_worker() mismanaged locking when worker creation fails
and it has to retry. Fix locking and simplify lock manipulation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yong Zhang <yong.zhang@windriver.com>
I have shown by code review that no driver takes
the BKL at init time any more, so whatever the
init code was locking against is no longer there
and it is now safe to remove the BKL there.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Steven Rostedt <rostedt@goodmis>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Variable on the stack is not initialized to zero, do it
explicitly.
This bug was found by a compiler warning:
kernel/watchdog.c:463: warning: 'result' may be used uninitialized in this function
Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1278316854-28442-1-git-send-email-segooon@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Support string type tracing and printing in kprobe-tracer.
This allows user to trace string data in kernel including __user data. Note
that sometimes __user data may not be accessed if it is paged-out (sorry, but
kprobes operation should be done in atomic, we can not wait for page-in).
Commiter note: Fixed up conflicts with b7e2ece.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100519195724.2885.18788.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We should initialize the module dynamic debug datastructures
only after determining that the module is not loaded yet. This
fixes a bug that introduced in 2.6.35-rc2, where when a trying
to load a module twice, we also load it's dynamic printing data
twice which causes all sorts of nasty issues. Also handle
the dynamic debug cleanup later on failure.
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed a #ifdef)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
WQ_SINGLE_CPU combined with @max_active of 1 is used to achieve full
ordering among works queued to a workqueue. The same can be achieved
using WQ_UNBOUND as unbound workqueues always use the gcwq for
WORK_CPU_UNBOUND. As @max_active is always one and benefits from cpu
locality isn't accessible anyway, serving them with unbound workqueues
should be fine.
Drop WQ_SINGLE_CPU support and use WQ_UNBOUND instead. Note that most
single thread workqueue users will be converted to use multithread or
non-reentrant instead and only the ones which require strict ordering
will keep using WQ_UNBOUND + @max_active of 1.
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch implements unbound workqueue which can be specified with
WQ_UNBOUND flag on creation. An unbound workqueue has the following
properties.
* It uses a dedicated gcwq with a pseudo CPU number WORK_CPU_UNBOUND.
This gcwq is always online and disassociated.
* Workers are not bound to any CPU and not concurrency managed. Works
are dispatched to workers as soon as possible and the only applied
limitation is @max_active. IOW, all unbound workqeueues are
implicitly high priority.
Unbound workqueues can be used as simple execution context provider.
Contexts unbound to any cpu are served as soon as possible.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: David Howells <dhowells@redhat.com>
In preparation of WQ_UNBOUND addition, make the following changes.
* Add WORK_CPU_* constants for pseudo cpu id numbers used (currently
only WORK_CPU_NONE) and use them instead of NR_CPUS. This is to
allow another pseudo cpu id for unbound cpu.
* Reorder WQ_* flags.
* Make workqueue_struct->cpu_wq a union which contains a percpu
pointer, regular pointer and an unsigned long value and use
kzalloc/kfree() in UP allocation path. This will be used to
implement unbound workqueues which will use only one cwq on SMPs.
* Move alloc_cwqs() allocation after initialization of wq fields, so
that alloc_cwqs() has access to wq->flags.
* Trivial relocation of wq local variables in freeze functions.
These changes don't cause any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
When there's no pending work to do, worker_thread() goes back to sleep
after waking up without checking whether worker management is
necessary. This means that idle worker exit requests can be ignored
if the gcwq stays empty.
Fix it by making worker_thread() always check whether worker
management is necessary before going to sleep.
Signed-off-by: Tejun Heo <tj@kernel.org>
get_work_gcwq() was incorrectly triggering BUG_ON() if cpu number is
equal to or higher than num_possible_cpus() instead of nr_cpu_ids.
Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
When one flusher is cascading to the next flusher, it first sets
wq->first_flusher to the next one and sets up the next flush cycle.
If there's nothing to do for the next cycle, it clears
wq->flush_flusher and proceeds to the one after that.
If the woken up flusher checks wq->first_flusher before it gets
cleared, it will incorrectly assume the role of the first flusher,
which triggers BUG_ON() sanity check.
Fix it by checking wq->first_flusher again after grabbing the mutex.
Signed-off-by: Tejun Heo <tj@kernel.org>
worker_set/clr_flags() assume that if none of NOT_RUNNING flags is set
the worker must be contributing to nr_running which is only true if
the worker is actually running.
As when called from self, it is guaranteed that the worker is running,
those functions can be safely used from the worker itself and they
aren't necessary from other places anyway. Make the following changes
to fix the bug.
* Make worker_set/clr_flags() whine if not called from self.
* Convert all places which called those functions from other tasks to
manipulate flags directly.
* Make trustee_thread() directly clear nr_running after setting
WORKER_ROGUE on all workers. This is the only place where
nr_running manipulation is necessary outside of workers themselves.
* While at it, add sanity check for nr_running in worker_enter_idle().
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit 0224cf4c5e (sched: Intoduce get_cpu_iowait_time_us())
broke things by not making sure preemption was indeed disabled
by the callers of nr_iowait_cpu() which took the iowait value of
the current cpu.
This resulted in a heap of preempt warnings. Cure this by making
nr_iowait_cpu() take a cpu number and fix up the callers to pass
in the right number.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-pm@lists.linux-foundation.org
LKML-Reference: <1277968037.1868.120.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Conflicts:
fs/fs-writeback.c
Merge reason: Resolve the conflict
Note, i picked the version from Linus's tree, which effectively reverts
the fs-writeback.c bits of:
b97181f: fs: remove all rcu head initializations, except on_stack initializations
As the upstream changes to this file changed this code heavily and the
first attempt to resolve the conflict resulted in a non-booting kernel.
It's safer to re-try this portion of the commit cleanly.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
futex_find_get_task is currently used (through lookup_pi_state) from two
contexts, futex_requeue and futex_lock_pi_atomic. None of the paths
looks it needs the credentials check, though. Different (e)uids
shouldn't matter at all because the only thing that is important for
shared futex is the accessibility of the shared memory.
The credentail check results in glibc assert failure or process hang (if
glibc is compiled without assert support) for shared robust pthread
mutex with priority inheritance if a process tries to lock already held
lock owned by a process with a different euid:
pthread_mutex_lock.c:312: __pthread_mutex_lock_full: Assertion `(-(e)) != 3 || !robust' failed.
The problem is that futex_lock_pi_atomic which is called when we try to
lock already held lock checks the current holder (tid is stored in the
futex value) to get the PI state. It uses lookup_pi_state which in turn
gets task struct from futex_find_get_task. ESRCH is returned either
when the task is not found or if credentials check fails.
futex_lock_pi_atomic simply returns if it gets ESRCH. glibc code,
however, doesn't expect that robust lock returns with ESRCH because it
should get either success or owner died.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When crashkernel is not enabled, "echo 0 > /sys/kernel/kexec_crash_size"
OOPSes the kernel in crash_shrink_memory. This happens when
crash_shrink_memory tries to release the 'crashk_res' resource which are
not reserved. Also value of "/sys/kernel/kexec_crash_size" shows as 1,
which should be 0.
This patch fixes the OOPS in crash_shrink_memory and shows
"/sys/kernel/kexec_crash_size" as 0 when crash kernel memory is not
reserved.
Signed-off-by: Pavan Naregundi <pavan@linux.vnet.ibm.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No logic changes, only spelling.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@ozlabs.org
Cc: David Howells <dhowells@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <15249.1277776921@neuling.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch implements cpu intensive workqueue which can be specified
with WQ_CPU_INTENSIVE flag on creation. Works queued to a cpu
intensive workqueue don't participate in concurrency management. IOW,
it doesn't contribute to gcwq->nr_running and thus doesn't delay
excution of other works.
Note that although cpu intensive works won't delay other works, they
can be delayed by other works. Combine with WQ_HIGHPRI to avoid being
delayed by other works too.
As the name suggests this is useful when using workqueue for cpu
intensive works. Workers executing cpu intensive works are not
considered for workqueue concurrency management and left for the
scheduler to manage.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
This patch implements high priority workqueue which can be specified
with WQ_HIGHPRI flag on creation. A high priority workqueue has the
following properties.
* A work queued to it is queued at the head of the worklist of the
respective gcwq after other highpri works, while normal works are
always appended at the end.
* As long as there are highpri works on gcwq->worklist,
[__]need_more_worker() remains %true and process_one_work() wakes up
another worker before it start executing a work.
The above two properties guarantee that works queued to high priority
workqueues are dispatched to workers and start execution as soon as
possible regardless of the state of other works.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Implement the following utility APIs.
workqueue_set_max_active() : adjust max_active of a wq
workqueue_congested() : test whether a wq is contested
work_cpu() : determine the last / current cpu of a work
work_busy() : query whether a work is busy
* Anton Blanchard fixed missing ret initialization in work_busy().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Blanchard <anton@samba.org>
This patch makes changes to make new workqueue features available to
its users.
* Now that workqueue is more featureful, there should be a public
workqueue creation function which takes paramters to control them.
Rename __create_workqueue() to alloc_workqueue() and make 0
max_active mean WQ_DFL_ACTIVE. In the long run, all
create_workqueue_*() will be converted over to alloc_workqueue().
* To further unify access interface, rename keventd_wq to system_wq
and export it.
* Add system_long_wq and system_nrt_wq. The former is to host long
running works separately (so that flush_scheduled_work() dosen't
take so long) and the latter guarantees any queued work item is
never executed in parallel by multiple CPUs. These will be used by
future patches to update workqueue users.
Signed-off-by: Tejun Heo <tj@kernel.org>
Define WQ_MAX_ACTIVE and create keventd with max_active set to half of
it which means that keventd now can process upto WQ_MAX_ACTIVE / 2 - 1
works concurrently. Unless some combination can result in dependency
loop longer than max_active, deadlock won't happen and thus it's
unnecessary to check whether current_is_keventd() before trying to
schedule a work. Kill current_is_keventd().
(Lockdep annotations are broken. We need lock_map_acquire_read_norecurse())
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Instead of creating a worker for each cwq and putting it into the
shared pool, manage per-cpu workers dynamically.
Works aren't supposed to be cpu cycle hogs and maintaining just enough
concurrency to prevent work processing from stalling due to lack of
processing context is optimal. gcwq keeps the number of concurrent
active workers to minimum but no less. As long as there's one or more
running workers on the cpu, no new worker is scheduled so that works
can be processed in batch as much as possible but when the last
running worker blocks, gcwq immediately schedules new worker so that
the cpu doesn't sit idle while there are works to be processed.
gcwq always keeps at least single idle worker around. When a new
worker is necessary and the worker is the last idle one, the worker
assumes the role of "manager" and manages the worker pool -
ie. creates another worker. Forward-progress is guaranteed by having
dedicated rescue workers for workqueues which may be necessary while
creating a new worker. When the manager is having problem creating a
new worker, mayday timer activates and rescue workers are summoned to
the cpu and execute works which might be necessary to create new
workers.
Trustee is expanded to serve the role of manager while a CPU is being
taken down and stays down. As no new works are supposed to be queued
on a dead cpu, it just needs to drain all the existing ones. Trustee
continues to try to create new workers and summon rescuers as long as
there are pending works. If the CPU is brought back up while the
trustee is still trying to drain the gcwq from the previous offlining,
the trustee will kill all idles ones and tell workers which are still
busy to rebind to the cpu, and pass control over to gcwq which assumes
the manager role as necessary.
Concurrency managed worker pool reduces the number of workers
drastically. Only workers which are necessary to keep the processing
going are created and kept. Also, it reduces cache footprint by
avoiding unnecessarily switching contexts between different workers.
Please note that this patch does not increase max_active of any
workqueue. All workqueues can still only process one work per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement worker_{set|clr}_flags() to manipulate worker flags. These
are currently simple wrappers but logics to track the current worker
state and the current level of concurrency will be added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Use gcwq->worklist instead of cwq->worklist and break the strict
association between a cwq and its worker. All works queued on a cpu
are queued on gcwq->worklist and processed by any available worker on
the gcwq.
As there no longer is strict association between a cwq and its worker,
whether a work is executing can now only be determined by calling
[__]find_worker_executing_work().
After this change, the only association between a cwq and its worker
is that a cwq puts a worker into shared worker pool on creation and
kills it on destruction. As all workqueues are still limited to
max_active of one, this means that there are always at least as many
workers as active works and thus there's no danger for deadlock.
The break of strong association between cwqs and workers requires
somewhat clumsy changes to current_is_keventd() and
destroy_workqueue(). Dynamic worker pool management will remove both
clumsy changes. current_is_keventd() won't be necessary at all as the
only reason it exists is to avoid queueing a work from a work which
will be allowed just fine. The clumsy part of destroy_workqueue() is
added because a worker can only be destroyed while idle and there's no
guarantee a worker is idle when its wq is going down. With dynamic
pool management, workers are not associated with workqueues at all and
only idle ones will be submitted to destroy_workqueue() so the code
won't be necessary anymore.
Signed-off-by: Tejun Heo <tj@kernel.org>
With gcwq managing all the workers and work->data pointing to the last
gcwq it was on, non-reentrance can be easily implemented by checking
whether the work is still running on the previous gcwq on queueing.
Implement it.
Signed-off-by: Tejun Heo <tj@kernel.org>
To implement non-reentrant workqueue, the last gcwq a work was
executed on must be reliably obtainable as long as the work structure
is valid even if the previous workqueue has been destroyed.
To achieve this, work->data will be overloaded to carry the last cpu
number once execution starts so that the previous gcwq can be located
reliably. This means that cwq can't be obtained from work after
execution starts but only gcwq.
Implement set_work_{cwq|cpu}(), get_work_[g]cwq() and
clear_work_data() to set work data to the cpu number when starting
execution, access the overloaded work data and clear it after
cancellation.
queue_delayed_work_on() is updated to preserve the last cpu while
in-flight in timer and other callers which depended on getting cwq
from work after execution starts are converted to depend on gcwq
instead.
* Anton Blanchard fixed compile error on powerpc due to missing
linux/threads.h include.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Blanchard <anton@samba.org>
Now that all the workers are tracked by gcwq, we can find which worker
is executing a work from gcwq. Implement find_worker_executing_work()
and make worker track its current_cwq so that we can find things the
other way around. This will be used to implement non-reentrant wqs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reimplement st (single thread) workqueue so that it's friendly to
shared worker pool. It was originally implemented by confining st
workqueues to use cwq of a fixed cpu and always having a worker for
the cpu. This implementation isn't very friendly to shared worker
pool and suboptimal in that it ends up crossing cpu boundaries often.
Reimplement st workqueue using dynamic single cpu binding and
cwq->limit. WQ_SINGLE_THREAD is replaced with WQ_SINGLE_CPU. In a
single cpu workqueue, at most single cwq is bound to the wq at any
given time. Arbitration is done using atomic accesses to
wq->single_cpu when queueing a work. Once bound, the binding stays
till the workqueue is drained.
Note that the binding is never broken while a workqueue is frozen.
This is because idle cwqs may have works waiting in delayed_works
queue while frozen. On thaw, the cwq is restarted if there are any
delayed works or unbound otherwise.
When combined with max_active limit of 1, single cpu workqueue has
exactly the same execution properties as the original single thread
workqueue while allowing sharing of per-cpu workers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reimplement CPU hotplugging support using trustee thread. On CPU
down, a trustee thread is created and each step of CPU down is
executed by the trustee and workqueue_cpu_callback() simply drives and
waits for trustee state transitions.
CPU down operation no longer waits for works to be drained but trustee
sticks around till all pending works have been completed. If CPU is
brought back up while works are still draining,
workqueue_cpu_callback() tells trustee to step down and tell workers
to rebind to the cpu.
As it's difficult to tell whether cwqs are empty if it's freezing or
frozen, trustee doesn't consider draining to be complete while a gcwq
is freezing or frozen (tracked by new GCWQ_FREEZING flag). Also,
workers which get unbound from their cpu are marked with WORKER_ROGUE.
Trustee based implementation doesn't bring any new feature at this
point but it will be used to manage worker pool when dynamic shared
worker pool is implemented.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement worker states. After created, a worker is STARTED. While a
worker isn't processing a work, it's IDLE and chained on
gcwq->idle_list. While processing a work, a worker is BUSY and
chained on gcwq->busy_hash. Also, gcwq now counts the number of all
workers and idle ones.
worker_thread() is restructured to reflect state transitions.
cwq->more_work is removed and waking up a worker makes it check for
events. A worker is killed by setting DIE flag while it's IDLE and
waking it up.
This gives gcwq better visibility of what's going on and allows it to
find out whether a work is executing quickly which is necessary to
have multiple workers processing the same cwq.
Signed-off-by: Tejun Heo <tj@kernel.org>
There is one gcwq (global cwq) per each cpu and all cwqs on an cpu
point to it. A gcwq contains a lock to be used by all cwqs on the cpu
and an ida to give IDs to workers belonging to the cpu.
This patch introduces gcwq, moves worker_ida into gcwq and make all
cwqs on the same cpu use the cpu's gcwq->lock instead of separate
locks. gcwq->ida is now protected by gcwq->lock too.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, workqueue freezing is implemented by marking the worker
freezeable and calling try_to_freeze() from dispatch loop.
Reimplement it using cwq->limit so that the workqueue is frozen
instead of the worker.
* workqueue_struct->saved_max_active is added which stores the
specified max_active on initialization.
* On freeze, all cwq->max_active's are quenched to zero. Freezing is
complete when nr_active on all cwqs reach zero.
* On thaw, all cwq->max_active's are restored to wq->saved_max_active
and the worklist is repopulated.
This new implementation allows having single shared pool of workers
per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Add cwq->nr_active, cwq->max_active and cwq->delayed_work. nr_active
counts the number of active works per cwq. A work is active if it's
flushable (colored) and is on cwq's worklist. If nr_active reaches
max_active, new works are queued on cwq->delayed_work and activated
later as works on the cwq complete and decrement nr_active.
cwq->max_active can be specified via the new @max_active parameter to
__create_workqueue() and is set to 1 for all workqueues for now. As
each cwq has only single worker now, this double queueing doesn't
cause any behavior difference visible to its users.
This will be used to reimplement freeze/thaw and implement shared
worker pool.
Signed-off-by: Tejun Heo <tj@kernel.org>
A work is linked to the next one by having WORK_STRUCT_LINKED bit set
and these links can be chained. When a linked work is dispatched to a
worker, all linked works are dispatched to the worker's newly added
->scheduled queue and processed back-to-back.
Currently, as there's only single worker per cwq, having linked works
doesn't make any visible behavior difference. This change is to
prepare for multiple shared workers per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Separate out worker thread related information to struct worker from
struct cpu_workqueue_struct and implement helper functions to deal
with the new struct worker. The only change which is visible outside
is that now workqueue worker are all named "kworker/CPUID:WORKERID"
where WORKERID is allocated from per-cpu ida.
This is in preparation of concurrency managed workqueue where shared
multiple workers would be available per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reimplement workqueue flushing using color coded works. wq has the
current work color which is painted on the works being issued via
cwqs. Flushing a workqueue is achieved by advancing the current work
colors of cwqs and waiting for all the works which have any of the
previous colors to drain.
Currently there are 16 possible colors, one is reserved for no color
and 15 colors are useable allowing 14 concurrent flushes. When color
space gets full, flush attempts are batched up and processed together
when color frees up, so even with many concurrent flushers, the new
implementation won't build up huge queue of flushers which has to be
processed one after another.
Only works which are queued via __queue_work() are colored. Works
which are directly put on queue using insert_work() use NO_COLOR and
don't participate in workqueue flushing. Currently only works used
for work-specific flush fall in this category.
This new implementation leaves only cleanup_workqueue_thread() as the
user of flush_cpu_workqueue(). Just make its users use
flush_workqueue() and kthread_stop() directly and kill
cleanup_workqueue_thread(). As workqueue flushing doesn't use barrier
request anymore, the comment describing the complex synchronization
around it in cleanup_workqueue_thread() is removed together with the
function.
This new implementation is to allow having and sharing multiple
workers per cpu.
Please note that one more bit is reserved for a future work flag by
this patch. This is to avoid shifting bits and updating comments
later.
Signed-off-by: Tejun Heo <tj@kernel.org>
work->data field is used for two purposes. It points to cwq it's
queued on and the lower bits are used for flags. Currently, two bits
are reserved which is always safe as 4 byte alignment is guaranteed on
every architecture. However, future changes will need more flag bits.
On SMP, the percpu allocator is capable of honoring larger alignment
(there are other users which depend on it) and larger alignment works
just fine. On UP, percpu allocator is a thin wrapper around
kzalloc/kfree() and don't honor alignment request.
This patch introduces WORK_STRUCT_FLAG_BITS and implements
alloc/free_cwqs() which guarantees max(1 << WORK_STRUCT_FLAG_BITS,
__alignof__(unsigned long long) alignment both on SMP and UP. On SMP,
simply wrapping percpu allocator is enough. On UP, extra space is
allocated so that cwq can be aligned and the original pointer can be
stored after it which is used in the free path.
* Alignment problem on UP is reported by Michal Simek.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Reported-by: Michal Simek <michal.simek@petalogix.com>
Worker management is about to be overhauled. Simplify things by
removing cpu_populated_map, creating workers for all possible cpus and
making single threaded workqueues behave more like multi threaded
ones.
After this patch, all cwqs are always initialized, all workqueues are
linked on the workqueues list and workers for all possibles cpus
always exist. This also makes CPU hotplug support simpler - checking
->cpus_allowed before processing works in worker_thread() and flushing
cwqs on CPU_POST_DEAD are enough.
While at it, make get_cwq() always return the cwq for the specified
cpu, add target_cwq() for cases where single thread distinction is
necessary and drop all direct usage of per_cpu_ptr() on wq->cpu_wq.
Signed-off-by: Tejun Heo <tj@kernel.org>
Strip tracing code from workqueue and remove workqueue tracing. This
is temporary measure till concurrency managed workqueue is complete.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Work flags are about to see more traditional mask handling. Define
WORK_STRUCT_*_BIT as the bit position constant and redefine
WORK_STRUCT_* as bit masks. Also, make WORK_STRUCT_STATIC_* flags
conditional
While at it, re-define these constants as enums and use
WORK_STRUCT_STATIC instead of hard-coding 2 in
WORK_DATA_STATIC_INIT().
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, __create_workqueue_key() takes @singlethread and
@freezeable paramters and store them separately in workqueue_struct.
Merge them into a single flags parameter and field and use
WQ_FREEZEABLE and WQ_SINGLE_THREAD.
Signed-off-by: Tejun Heo <tj@kernel.org>
Make the following updates in preparation of concurrency managed
workqueue. None of these changes causes any visible behavior
difference.
* Add comments and adjust indentations to data structures and several
functions.
* Rename wq_per_cpu() to get_cwq() and swap the position of two
parameters for consistency. Convert a direct per_cpu_ptr() access
to wq->cpu_wq to get_cwq().
* Add work_static() and Update set_wq_data() such that it sets the
flags part to WORK_STRUCT_PENDING | WORK_STRUCT_STATIC if static |
@extra_flags.
* Move santiy check on work->entry emptiness from queue_work_on() to
__queue_work() which all queueing paths share.
* Make __queue_work() take @cpu and @wq instead of @cwq.
* Restructure flush_work() and __create_workqueue_key() to make them
easier to modify.
Signed-off-by: Tejun Heo <tj@kernel.org>
With stop_machine() converted to use cpu_stop, RT workqueue doesn't
have any user left. Kill RT workqueue support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement kthread_data() which takes @task pointing to a kthread and
returns @data specified when creating the kthread. The caller is
responsible for ensuring the validity of @task when calling this
function.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement simple work processor for kthread. This is to ease using
kthread. Single thread workqueue used to be used for things like this
but workqueue won't guarantee fixed kthread association anymore to
enable worker sharing.
This can be used in cases where specific kthread association is
necessary, for example, when it should have RT priority or be assigned
to certain cgroup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
