Commit graph

255070 commits

Author SHA1 Message Date
Dan Carpenter
0528f354cf [media] rc: double unlock in rc_register_device()
If change_protocol() fails and we goto out_raw, then it calls unlock
twice.  I noticed that the other time we called change_protocol() we
held the &dev->lock, so I changed it to hold it here too.

Reviewed-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:24 -03:00
Andreas Oberritter
ec05a64214 [media] DVB: dvb_frontend: fix dtv_property_dump for DTV_DVBT2_PLP_ID
- Add missing entry to array "dtv_cmds".
- Set array size to DTV_MAX_COMMAND + 1 to avoid future off-by-ones.

Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:24 -03:00
Uwe Kleine-König
7f116b3ea9 [media] V4L/videobuf2-memops: use pr_debug for debug messages
Otherwise they clutter the dmesg buffer even on a production kernel.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:23 -03:00
Manoel Pinheiro
147b68cd7e [media] dvb-usb.h function rc5_scan
The function "rc5_scan" in "dvb_usb.h" is returning invalid value.
The value should be returned "u16" but is returning "u8".

See example below in "drivers/media/dvb/dvb-usb/opera1.c":

        send_key = (send_key & 0xffff) | 0x0100;

        for (i = 0; i < ARRAY_SIZE(rc_map_opera1_table); i++) {
            if (rc5_scan(&rc_map_opera1_table[i]) == (send_key & 0xffff)) {
                *state = REMOTE_KEY_PRESSED;
                *event = rc_map_opera1_table[i].keycode;
                opst->last_key_pressed =
                    rc_map_opera1_table[i].keycode;
                break;
            }
            opst->last_key_pressed = 0;
        }

Signed-off-by: Manoel Pinheiro <pinusdtv@hotmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:23 -03:00
Ondrej Zary
9e8fa0e644 [media] radio-sf16fmr2: convert to generic TEA575x interface
Convert radio-sf16fmr2 to use generic TEA575x implementation. Most of the
driver code goes away as SF16-FMR2 is basically just a TEA5757 tuner
connected to ISA bus.
The card can optionally be equipped with PT2254A volume control (equivalent
of TC9154AP) - the volume setting is completely reworked (with balance control
added) and tested.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:23 -03:00
Hans Petter Selasky
d294093010 [media] cx24113: Don't reuse core macro names
The info and err macros are already defined by the USB stack. Rename
these macros to avoid macro redefinition warnings.

Signed-off-by: Hans Petter Selasky <hselasky@c2i.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:22 -03:00
Hans Petter Selasky
a5bef1d252 [media] itd1000: Don't reuse core macro names
The dbg, warn and info macros are already defined by the USB stack.
Rename these macros to avoid macro redefinition warnings.

Refactor lineshift in printouts.

Signed-off-by: Hans Petter Selasky <hselasky@c2i.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:21 -03:00
Alexey Khoroshilov
f54ba7f199 [media] radio-si470x: fix memory leak in si470x_usb_driver_probe()
radio->int_in_urb is not deallocated on error paths in si470x_usb_driver_probe().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:21 -03:00
Joe Perches
fabc6b85ca [media] media: Convert vmalloc/memset to vzalloc
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:21 -03:00
Mauro Carvalho Chehab
fcc8e7d8c0 dvb_net: Simplify the code if DVB NET is not defined
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:20 -03:00
Hans Petter Selasky
a34ff6cdbb [media] Make DVB NET configurable in the kernel
Signed-off-by: Hans Petter Selasky <hselasky@c2i.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:20 -03:00
Ondrej Zary
4522e825db [media] tea575x: convert to control framework
Convert tea575x-tuner to use the new V4L2 control framework. Also add
ext_init() callback that can be used by a card driver for additional
initialization right before registering the video device (for SF16-FMR2).

Also embed struct video_device to struct snd_tea575x to simplify the code.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:20 -03:00
Hans Petter Selasky
2ef4037088 [media] Fix compile warning: Dereferencing type-punned pointer will break strict-aliasing rules
Signed-off-by: Hans Petter Selasky <hselasky@c2i.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:20 -03:00
Sakari Ailus
82f7b59cb8 [media] v4l: Document EACCES in VIDIOC_[GS]_CTRL and VIDIOC_{G, S, TRY}_EXT_CTRLS
VIDIOC_S_CTRL and VIDIOC_S_EXT_CTRLS return EACCES when setting a read-only
control VIDIOC_TRY_EXT_CTRLS when trying a read-only control and
VIDIOC_G_CTRL and VIDIOC_G_EXT_CTRLS when getting a write-only control.
Document this.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:19 -03:00
Newson Edouard
45f239ab82 [media] videobuf_pages_to_sg: sglist[0] length problem
On function videobuf_pages_to_sg the statement sg_set_page(&sglist[0],
pages[0], PAGE_SIZE - offset, offset) will fail if size is less than
PAGE_SIZE.

Signed-off-by: Newson Edouard <newsondev@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:19 -03:00
Tejun Heo
4bbcd849b0 [media] cx23885: restore flushes of cx23885_dev work items
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:18 -03:00
Dan Carpenter
061d55eb45 [media] saa7164: poll mask set incorrectly
list_first_entry() always returns non-null here.  I think the intent was
to test whether there were any entries in the used list.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:18 -03:00
Antti Palosaari
050bf0faa8 [media] cxd2820r: correct missing error checks
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:17 -03:00
Mauro Carvalho Chehab
58b0ed25b6 [media] Update several cardlists
Several cardlist entries are missed. Fix them by running some
script magic (about the same scripts we used to have at -hg tree).

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:16 -03:00
Mauro Carvalho Chehab
ebaefdb765 [media] em28xx: use the proper prefix for board names
All boards use EM28xxx_BOARD, to identify that the macro
refers to a card entry. So:

EM2874_LEADERSHIP_ISDBT -> EM2874_BOARD_LEADERSHIP_ISDBT

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:16 -03:00
Antti Palosaari
460312ec5a [media] em28xx: correct PCTV nanoStick T2 290e device name
PCTV Systems nanoStick T2 290e => PCTV nanoStick T2 290e

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:15 -03:00
Antti Palosaari
ff7b929f04 [media] em28xx: add remote for PCTV nanoStick T2 290e
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:14 -03:00
Antti Palosaari
a24ec44801 [media] em28xx: EM28174 remote support
For some reason it repeats rather slowly, around 800ms intervals,
two RC5 remotes tested.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:14 -03:00
Antti Palosaari
1d44ccb9ea [media] cxd2820r: fix bitfields
error: dubious one-bit signed bitfield

Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:10 -03:00
Antti Palosaari
d838f4c318 [media] cxd2820r: malloc buffers instead of stack
kmalloc I2C buffers

Signed-off-by: Antti Palosaari <crope@iki.fi>
Cc: Dan Carpenter <error27@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:09 -03:00
Antti Palosaari
05c46c05d2 [media] anysee: style issues, comments, etc
Change some info, comments, variables. No functionality changes.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:09 -03:00
Antti Palosaari
fea3c39a2e [media] anysee: add support for Anysee E7 PS2
Basically it is just same device as Anysee E7 S2 but made for
internal PCI(e) slot and motherboard USB connector.

Cc: info@anysee.com
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:07 -03:00
Antti Palosaari
8439e0df9c [media] anysee: add support for Anysee E7 PTC
Basically it is just same device as Anysee E7 TC but made for
internal PCI(e) slot and motherboard USB connector.

Cc: info@anysee.com
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:07 -03:00
Jean-François Moine
798ae1501d [media] gspca - ov519: New sensor ov9600 with bridge ovfx2
This sensor was found in a webcam 8020:ef04 (SVC - SVU2-1.3MV PCCam).

Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:06 -03:00
Mauro Carvalho Chehab
4266129964 [media] DocBook: Move all media docbook stuff into its own directory
This patch addresses several issues pointed by Randy Dunlap
<rdunlap@xenotime.net> at changeset ece722c:

- In the generated index.html file, "media" is listed first, but it
  should be listed in alphabetical order, not first.

- The generated files are (hidden) in .tmpmedia/

- The link from the top-level index.html file to "media" is to
  media/index.html, but the file is actually in .tmpmedia/media/index.html

- Please build docs with and without using "O=builddir" and test that.

- Would it be possible for media to have its own Makefile instead of
  merging into this one?

Due to the way cleandocs target works, I had to rename the media DocBook
to media_api, otherwise cleandocs would remove the /media directory.

Thanks-to: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:05 -03:00
Mauro Carvalho Chehab
04893043ae [media] DocBook: Add rules to auto-generate some media docbook
Auto-generate the videodev2.h.xml,frontend.h.xml and the indexes.

Some logic at the Makefile helps us to identify when a symbol is missing,
like for example:

Error: no ID for constraint linkend: V4L2-PIX-FMT-JPGL.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2011-07-27 17:52:01 -03:00
Linus Torvalds
02f8c6aee8 Linux 3.0 2011-07-21 19:17:23 -07:00
Linus Torvalds
1f922d0770 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  sparc,kgdbts: fix compile regression with kgdb test suite
2011-07-21 17:20:57 -07:00
Jason Wessel
33d8881af5 sparc,kgdbts: fix compile regression with kgdb test suite
Commit 63ab25ebbc (kgdbts: unify/generalize gdb breakpoint adjustment)
introduced a compile regression on sparc.

kgdbts.c: In function 'check_and_rewind_pc':
kgdbts.c:307: error: implicit declaration of function 'instruction_pointer_set'

Simply add the correct macro definition for instruction pointer on the
Sparc architecture.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: David S. Miller <davem@davemloft.net>
2011-07-21 17:29:49 -05:00
Linus Torvalds
2bafc7a275 Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6:
  CIFS: Fix wrong length in cifs_iovec_read
2011-07-21 14:28:01 -07:00
Linus Torvalds
57a6fa9acd Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Make Dell Latitude E6420 use reboot=pci
  x86: Make Dell Latitude E5420 use reboot=pci
2011-07-21 12:25:39 -07:00
H. Peter Anvin
a536877e77 x86: Make Dell Latitude E6420 use reboot=pci
Yet another variant of the Dell Latitude series which requires
reboot=pci.

From the E5420 bug report by Daniel J Blueman:

> The E6420 is affected also (same platform, different casing and
> features), which provides an external confirmation of the issue; I can
> submit a patch for that later or include it if you prefer:
> http://linux.koolsolutions.com/2009/08/04/howto-fix-linux-hangfreeze-during-reboots-and-restarts/

Reported-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@kernel.org>
2011-07-21 11:47:17 -07:00
Daniel J Blueman
b7798d28ec x86: Make Dell Latitude E5420 use reboot=pci
Rebooting on the Dell E5420 often hangs with the keyboard or ACPI
methods, but is reliable via the PCI method.

[ hpa: this was deferred because we believed for a long time that the
  recent reshuffling of the boot priorities in commit
  660e34cebf fixed this platform.
  Unfortunately that turned out to be incorrect. ]

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Link: http://lkml.kernel.org/r/1305248699-2347-1-git-send-email-daniel.blueman@gmail.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@kernel.org>
2011-07-21 11:45:49 -07:00
Linus Torvalds
ad21b11577 Merge branch 'drm-intel-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/keithp/linux-2.6
* 'drm-intel-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/keithp/linux-2.6:
  drm/i915: Fix unfenced alignment on pre-G33 hardware
  drm/i915: Add quirk to disable SSC on Lenovo U160 LVDS
2011-07-21 11:07:18 -07:00
Linus Torvalds
b91da88fed vfs: drop conditional inode prefetch in __do_lookup_rcu
It seems to hurt performance in real life.  Yes, the inode will be used
later, but the conditional doesn't seem to predict all that well
(negative dentries are not uncommon) and it looks like the cost of
prefetching is simply higher than depending on the cache doing the right
thing.

As usual.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-21 11:01:42 -07:00
Jan Beulich
b307d4655a FS-Cache: Fix __fscache_uncache_all_inode_pages()'s outer loop
The compiler, at least for ix86 and m68k, validly warns that the
comparison:

	next <= (loff_t)-1

is always true (and it's always true also for x86-64 and probably all
other arches - as long as pgoff_t isn't wider than loff_t).  The
intention appears to be to avoid wrapping of "next", so rather than
eliminating the pointless comparison, fix the loop to indeed get exited
when "next" would otherwise wrap.

On m68k the following warning is observed:

  fs/fscache/page.c: In function '__fscache_uncache_all_inode_pages':
  fs/fscache/page.c:979: warning: comparison is always false due to limited range of data type

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Suresh Jayaraman <sjayaraman@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-21 10:59:16 -07:00
Pavel Shilovsky
2cebaa58b7 CIFS: Fix wrong length in cifs_iovec_read
Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2011-07-21 00:48:05 +00:00
Linus Torvalds
cf6ace16a3 Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  signal: align __lock_task_sighand() irq disabling and RCU
  softirq,rcu: Inform RCU of irq_exit() activity
  sched: Add irq_{enter,exit}() to scheduler_ipi()
  rcu: protect __rcu_read_unlock() against scheduler-using irq handlers
  rcu: Streamline code produced by __rcu_read_unlock()
  rcu: Fix RCU_BOOST race handling current->rcu_read_unlock_special
  rcu: decrease rcu_report_exp_rnp coupling with scheduler
2011-07-20 15:56:25 -07:00
Linus Torvalds
acc11eab70 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Avoid creating superfluous NUMA domains on non-NUMA systems
  sched: Allow for overlapping sched_domain spans
  sched: Break out cpu_power from the sched_group structure
2011-07-20 15:55:48 -07:00
Linus Torvalds
919d25a710 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86. reboot: Make Dell Latitude E6320 use reboot=pci
  x86, doc only: Correct real-mode kernel header offset for init_size
  x86: Disable AMD_NUMA for 32bit for now
2011-07-20 15:33:59 -07:00
Ingo Molnar
d1e9ae47a0 Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/urgent 2011-07-20 20:59:26 +02:00
Paul E. McKenney
a841796f11 signal: align __lock_task_sighand() irq disabling and RCU
The __lock_task_sighand() function calls rcu_read_lock() with interrupts
and preemption enabled, but later calls rcu_read_unlock() with interrupts
disabled.  It is therefore possible that this RCU read-side critical
section will be preempted and later RCU priority boosted, which means that
rcu_read_unlock() will call rt_mutex_unlock() in order to deboost itself, but
with interrupts disabled. This results in lockdep splats, so this commit
nests the RCU read-side critical section within the interrupt-disabled
region of code.  This prevents the RCU read-side critical section from
being preempted, and thus prevents the attempt to deboost with interrupts
disabled.

It is quite possible that a better long-term fix is to make rt_mutex_unlock()
disable irqs when acquiring the rt_mutex structure's ->wait_lock.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-07-20 11:04:54 -07:00
Peter Zijlstra
ec433f0c51 softirq,rcu: Inform RCU of irq_exit() activity
The rcu_read_unlock_special() function relies on in_irq() to exclude
scheduler activity from interrupt level.  This fails because exit_irq()
can invoke the scheduler after clearing the preempt_count() bits that
in_irq() uses to determine that it is at interrupt level.  This situation
can result in failures as follows:

 $task			IRQ		SoftIRQ

 rcu_read_lock()

 /* do stuff */

 <preempt> |= UNLOCK_BLOCKED

 rcu_read_unlock()
   --t->rcu_read_lock_nesting

			irq_enter();
			/* do stuff, don't use RCU */
			irq_exit();
			  sub_preempt_count(IRQ_EXIT_OFFSET);
			  invoke_softirq()

					ttwu();
					  spin_lock_irq(&pi->lock)
					  rcu_read_lock();
					  /* do stuff */
					  rcu_read_unlock();
					    rcu_read_unlock_special()
					      rcu_report_exp_rnp()
					        ttwu()
					          spin_lock_irq(&pi->lock) /* deadlock */

   rcu_read_unlock_special(t);

Ed can simply trigger this 'easy' because invoke_softirq() immediately
does a ttwu() of ksoftirqd/# instead of doing the in-place softirq stuff
first, but even without that the above happens.

Cure this by also excluding softirqs from the
rcu_read_unlock_special() handler and ensuring the force_irqthreads
ksoftirqd/# wakeup is done from full softirq context.

[ Alternatively, delaying the ->rcu_read_lock_nesting decrement
  until after the special handling would make the thing more robust
  in the face of interrupts as well.  And there is a separate patch
  for that. ]

Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-and-tested-by: Ed Tomlinson <edt@aei.ca>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-07-20 10:50:12 -07:00
Peter Zijlstra
c5d753a55a sched: Add irq_{enter,exit}() to scheduler_ipi()
Ensure scheduler_ipi() calls irq_{enter,exit} when it does some actual
work. Traditionally we never did any actual work from the resched IPI
and all magic happened in the return from interrupt path.

Now that we do do some work, we need to ensure irq_{enter,exit} are
called so that we don't confuse things.

This affects things like timekeeping, NO_HZ and RCU, basically
everything with a hook in irq_enter/exit.

Explicit examples of things going wrong are:

  sched_clock_cpu() -- has a callback when leaving NO_HZ state to take
                    a new reading from GTOD and TSC. Without this
                    callback, time is stuck in the past.

  RCU -- needs in_irq() to work in order to avoid some nasty deadlocks

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-07-20 10:50:11 -07:00
Paul E. McKenney
10f39bb1b2 rcu: protect __rcu_read_unlock() against scheduler-using irq handlers
The addition of RCU read-side critical sections within runqueue and
priority-inheritance lock critical sections introduced some deadlock
cycles, for example, involving interrupts from __rcu_read_unlock()
where the interrupt handlers call wake_up().  This situation can cause
the instance of __rcu_read_unlock() invoked from interrupt to do some
of the processing that would otherwise have been carried out by the
task-level instance of __rcu_read_unlock().  When the interrupt-level
instance of __rcu_read_unlock() is called with a scheduler lock held
from interrupt-entry/exit situations where in_irq() returns false,
deadlock can result.

This commit resolves these deadlocks by using negative values of
the per-task ->rcu_read_lock_nesting counter to indicate that an
instance of __rcu_read_unlock() is in flight, which in turn prevents
instances from interrupt handlers from doing any special processing.
This patch is inspired by Steven Rostedt's earlier patch that similarly
made __rcu_read_unlock() guard against interrupt-mediated recursion
(see https://lkml.org/lkml/2011/7/15/326), but this commit refines
Steven's approach to avoid the need for preemption disabling on the
__rcu_read_unlock() fastpath and to also avoid the need for manipulating
a separate per-CPU variable.

This patch avoids need for preempt_disable() by instead using negative
values of the per-task ->rcu_read_lock_nesting counter.  Note that nested
rcu_read_lock()/rcu_read_unlock() pairs are still permitted, but they will
never see ->rcu_read_lock_nesting go to zero, and will therefore never
invoke rcu_read_unlock_special(), thus preventing them from seeing the
RCU_READ_UNLOCK_BLOCKED bit should it be set in ->rcu_read_unlock_special.
This patch also adds a check for ->rcu_read_unlock_special being negative
in rcu_check_callbacks(), thus preventing the RCU_READ_UNLOCK_NEED_QS
bit from being set should a scheduling-clock interrupt occur while
__rcu_read_unlock() is exiting from an outermost RCU read-side critical
section.

Of course, __rcu_read_unlock() can be preempted during the time that
->rcu_read_lock_nesting is negative.  This could result in the setting
of the RCU_READ_UNLOCK_BLOCKED bit after __rcu_read_unlock() checks it,
and would also result it this task being queued on the corresponding
rcu_node structure's blkd_tasks list.  Therefore, some later RCU read-side
critical section would enter rcu_read_unlock_special() to clean up --
which could result in deadlock if that critical section happened to be in
the scheduler where the runqueue or priority-inheritance locks were held.

This situation is dealt with by making rcu_preempt_note_context_switch()
check for negative ->rcu_read_lock_nesting, thus refraining from
queuing the task (and from setting RCU_READ_UNLOCK_BLOCKED) if we are
already exiting from the outermost RCU read-side critical section (in
other words, we really are no longer actually in that RCU read-side
critical section).  In addition, rcu_preempt_note_context_switch()
invokes rcu_read_unlock_special() to carry out the cleanup in this case,
which clears out the ->rcu_read_unlock_special bits and dequeues the task
(if necessary), in turn avoiding needless delay of the current RCU grace
period and needless RCU priority boosting.

It is still illegal to call rcu_read_unlock() while holding a scheduler
lock if the prior RCU read-side critical section has ever had either
preemption or irqs enabled.  However, the common use case is legal,
namely where then entire RCU read-side critical section executes with
irqs disabled, for example, when the scheduler lock is held across the
entire lifetime of the RCU read-side critical section.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-07-20 10:50:11 -07:00