Commit Graph

211 Commits (1ec320afdc9552c92191d5f89fcd1ebe588334ca)

Author SHA1 Message Date
Adrian Bunk 7d1362c0d0 [PATCH] cleanup asm/setup.h userspace visibility
Make the contents of the userspace asm/setup.h header consistent on all
architectures:

 - export setup.h to userspace on all architectures
 - export only COMMAND_LINE_SIZE to userspace
 - frv: move COMMAND_LINE_SIZE from param.h
 - i386: remove duplicate COMMAND_LINE_SIZE from param.h
 - arm:
   - export ATAGs to userspace
   - change u8/u16/u32 to __u8/__u16/__u32

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:46 -08:00
Ralf Baechle d3fa72e455 [PATCH] Pass struct dev pointer to dma_cache_sync()
Pass struct dev pointer to dma_cache_sync()

dma_cache_sync() is ill-designed in that it does not have a struct device
pointer argument which makes proper support for systems that consist of a
mix of coherent and non-coherent DMA devices hard.  Change dma_cache_sync
to take a struct device pointer as first argument and fix all its callers
to pass it.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:41 -08:00
Arnd Bergmann f5738ceed4 [PATCH] remove kernel syscalls
The last thing we agreed on was to remove the macros entirely for 2.6.19,
on all architectures. Unfortunately, I think nobody actually _did_ that,
so they are still there.

[akpm@osdl.org: x86_64 fix]
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Schafer <gschafer@zip.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:37 -08:00
Jamie Lenehan ea0f8feaa0 sh: sh775x/titan fixes for irq header changes.
The following moves the creation of IPR interupts into setup-7750.c
and updates a few other things to make it all work after the "Drop
CPU subtype IRQ headers" commit. It boots and runs fine on my titan
board.

 - adds an ipr_idx to the ipr_data and uses a function in the subtype
   code to calculate the address of the IPR registers

 - adds a function to enable individual interrupt mode for externals
   in the subtype code and calls that from the titan board code
   instead of doing it directly.

 - I changed the shift in the ipr_data to be the actual # of bits to
   shift, instead of the numnber / 4 - made it easier to match with
   the manual.

Signed-off-by: Jamie Lenehan <lenehan@twibble.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 12:05:02 +09:00
Paul Mundt 5b67954e80 sh: Fixup pte_mkhuge() build failure.
When hugetlbpage support isn't enabled, this can be bogus.
Wrap it back in _PAGE_FLAGS_HARD to avoid changes to the
base PTE when not aiming for larger sizes.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 11:20:53 +09:00
Paul Mundt afbfb52e47 sh: stacktrace/lockdep/irqflags tracing support.
Wire up all of the essentials for lockdep..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:40 +09:00
Paul Mundt c03c69610b sh: Fixup movli.l/movco.l atomic ops for gcc4.
gcc4 gets a bit pissy about the outputs:

include/asm/atomic.h: In function 'atomic_add':
include/asm/atomic.h:37: error: invalid lvalue in asm statement
include/asm/atomic.h:30: error: invalid lvalue in asm output 1
...

this ended up being a thinko anyways, so just fix it up.

Verified for proper behaviour with the older toolchains, too.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:40 +09:00
Paul Mundt bd156147eb sh: dyntick infrastructure.
This adds basic NO_IDLE_HZ support to the SH timer API so timers
are able to wire it up. Taken from the ARM version, as it fit in
to our API with very few changes needed.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:40 +09:00
Paul Mundt 1d118562c2 sh: Clock framework tidying.
This syncs up the SH clock framework with the linux/clk.h API,
for which there were only some minor changes required, namely
the clk_get() dev_id and subsequent callsites.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:40 +09:00
Paul Mundt 510c72ad2d sh: Fixup various PAGE_SIZE == 4096 assumptions.
There were a number of places that made evil PAGE_SIZE == 4k
assumptions that ended up breaking when trying to play with
8k and 64k page sizes, this fixes those up.

The most significant change is the way we load THREAD_SIZE,
previously this was done via:

	mov	#(THREAD_SIZE >> 8), reg
	shll8	reg

to avoid a memory access and allow the immediate load. With
a 64k PAGE_SIZE, we're out of range for the immediate load
size without resorting to special instructions available in
later ISAs (movi20s and so on). The "workaround" for this is
to bump up the shift to 10 and insert a shll2, which gives a
bit more flexibility while still being much cheaper than a
memory access.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:39 +09:00
Mark Glaisher db9b99d461 sh: dma-api channel capability extensions.
This extends the SH DMA API for allowing handling of DMA
channels based off of their respective capabilities.

A couple of functions are added to the existing API,
the core bits are register_chan_caps() for registering
channel capabilities, and request_dma_bycap() for fetching
a channel dynamically based off of a capability set.

Signed-off-by: Mark Glaisher <mark.glaisher@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:39 +09:00
Stuart Menefy c9f0b1c141 sh: KSTK_EIP/KSTK_ESP consistency.
Two of the fields in /proc/[number]/stat are documented in
proc(5) as:

      kstkesp %lu
	     The current value of esp (stack pointer), as
	     found in the kernel stack page for the process.

      kstkeip %lu
	     The current EIP (instruction pointer).

The SH currently prints the the last SP and PC of the process
inside the kernel, while most other archs use the last user
space values.

This patch modifes the SH to display the user space values.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:38 +09:00
Stuart Menefy 9b3a53ab76 sh: TLB miss fast-path optimizations.
Handle simple TLB miss faults which can be resolved completely
from the page table in assembler.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:38 +09:00
Paul Mundt 9f5e8eee5c sh: generic push-switch framework.
This adds support for a generic push switch framework. Adaptable for
various switches, including GPIO switches and the push switches commonly
found on Renesas debug boards.

This allows switch states to be trivially reported through sysfs.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:38 +09:00
Stuart Menefy 99a596f93b sh: pmd rework.
Remove extra bits from the pmd structure and store a kernel logical
address rather than a physical address. This allows it to be directly
dereferenced. Another piece of wierdness inherited from x86.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:38 +09:00
Stuart Menefy 6e4662ff49 sh: Use MMU.TTB register as pointer to current pgd.
Add TTB accessor functions and give it a sensible default
value. We will use this later for optimizing the fault
path.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:38 +09:00
Stuart Menefy b5a1bcbee4 sh: Set up correct siginfo structures for page faults.
Remove the previous saving of fault codes into the thread_struct
as they are never used, and appeared to be inherited from x86.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:38 +09:00
Paul Mundt 21440cf04a sh: Preliminary support for SH-X2 MMU.
This adds some preliminary support for the SH-X2 MMU, used by
newer SH-4A parts (particularly SH7785).

This MMU implements a 'compat' mode with SH-X MMUs and an
'extended' mode for SH-X2 extended features. Extended features
include additional page sizes (8kB, 4MB, 64MB), as well as the
addition of page execute permissions.

The extended mode attributes are placed in a second data array,
which requires us to switch to 64-bit PTEs when in X2 mode.

With the addition of the exec perms, we also overhaul the mmap
prots somewhat, now that it's possible to handle them more
intelligently.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:37 +09:00
Paul Mundt b552c7e8bc sh: Hook SH7785 in to the build system.
Simple 7785 placeholders to start hooking up other bits of code.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:37 +09:00
Paul Mundt 9a7ef6d59f sh: Drop CPU subtype IRQ headers.
This drops the various IRQ headers that were floating around
and primarily providing hardcoded IRQ definitions for the
various CPU subtypes. This quickly got to be an unmaintainable
mess, made even more evident by the subtle breakage introduced
by the SH-2 and SH-2A changes.

Now that subtypes are able to register IRQ maps directly, just
rip all of the headers out.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:37 +09:00
Paul Mundt 710ee0cc45 sh: SE7206 build fixes.
A number of API changes happened underneath the 7206 patches, update
for everything that broke.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:37 +09:00
Yoshinori Sato b229632abd sh: Add SH-2A platform headers.
Mostly SH-2 wrappers..

Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-06 10:45:36 +09:00
Matthew Wilcox e62438630c [PATCH] Centralise definitions of sector_t and blkcnt_t
CONFIG_LBD and CONFIG_LSF are spread into asm/types.h for no particularly
good reason.

Centralising the definition in linux/types.h means that arch maintainers
don't need to bother adding it, as well as fixing the problem with
x86-64 users being asked to make a decision that has absolutely no
effect.

The H8/300 porters seem particularly confused since I'm not aware of any
microcontrollers that need to support 2TB filesystems.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-04 19:41:15 -08:00
Al Viro 7c73a746ba [NET]: SH checksum annotations and cleanups.
* sanitize prototypes, annotate
* kill useless shifts
* usual ntohs->shift

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 21:23:22 -08:00
Benjamin Herrenschmidt c6dbaef22a Driver core: add dev_archdata to struct device
Add arch specific dev_archdata to struct device

Adds an arch specific struct dev_arch to struct device. This enables
architecture to add specific fields to every device in the system, like
DMA operation pointers, NUMA node ID, firmware specific data, etc...

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Andi Kleen <ak@suse.de>
Acked-By: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-12-01 14:52:01 -08:00
Jamie Lenehan bd71ab88de sh: Fix IPR-IRQ's for IRQ-chip change breakage.
The conversion from IPR-IRQ to IRQ-chip resulted in the
ipr data being allocated in a local variable in
make_ipr_irq - breaking anything using IPR interrupts.

This changes all of the callers of make_ipr_irq to
allocate a static structure containing the IPR data which
is then passed to make_ipr_irq. This removes the need for
make_ipr_irq to allocate any additional space for the IPR
information.

Signed-off-by: Jamie Lenehan <lenehan@twibble.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-31 12:53:28 +09:00
Paul Mundt 6887d83d6a sh: Wire up new syscalls.
This wires up sys_move_pages, sys_getcpu, and sys_epoll_pwait.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-31 12:53:28 +09:00
Paul Mundt 66a740572d sh: Convert INTC2 to IRQ table registration.
Currently the INTC2 code contains a fixed IRQ table that it
iterates through to set the handler type, we move this in to
the CPU subtype setup code instead and allow for submitting
the table that way.

This drops the ST40 tables, as nothing has been happening
with those processors, while converting the only existing
users to use the new table directly (SH7760 and SH7780).

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-20 15:30:55 +09:00
Paul Mundt c2a560f533 sh: Add some missing board headers.
Some of these were dropped in the header directory rework, add
the few missing ones back in.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-19 17:31:22 +09:00
Paul Mundt 1f666587db sh: Fix exception_handling_table alignment.
With the recent change ripping out interrupt_table, explicit
padding of the table was missing, causing bad things to happen
when manually inserting handlers in to the table. This problem
particularly showed up in relation to do_fpu_state_restore()
which was inserted quite deeply in to the table and ended up
scribbling over a slab object.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-19 16:30:32 +09:00
Paul Mundt 082c44d20e sh: Cleanup board header directories.
Now with the ide.h mess sorted out, most of these boards
don't need their own directory. Move the headers out, and
update the driver paths.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-19 16:30:32 +09:00
Paul Mundt 4a58eaca7c sh: Remove board-specific ide.h headers.
The driver that these were using never made it in to
drivers/ide, so kill off the rest of the cruft. These
will have to be reworked for board-specific platform
devices through libata when they're added back through
the setup code.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-19 16:30:32 +09:00
Paul Mundt 6b0022305f sh: Proper show_stack/show_trace() implementation.
This splits out some of the previous show_stack() implementation which
was mostly doing the show_trace() work without actually dumping any of
the stack contents. This now gets split in to two sections, where we
do the fetching of the stack pointer and subsequent stack dumping in
show_stack(), while moving the call trace in to show_trace().

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-19 16:30:31 +09:00
Linus Torvalds 9eb2007488 Merge master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6
* master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6:
  sh: SH-4A UBC support
  sh: interrupt exception handling rework
  sh: Default enable R7780RP IRQs.
  sh: Zero-out coherent buffer in consistent_alloc().
  sh: Convert IPR-IRQ to IRQ chip.
  sh: Convert INTC2 IRQ handler to irq_chip.
  sh: Fix pr_debug statements for sh4
  sh: Convert r7780rp IRQ handler to IRQ chip.
  sh: Updates for IRQ handler changes.
  sh: Kill off timer_ops get_frequency().
  sh: First step at generic timeofday support.
2006-10-12 08:33:23 -07:00
Ryusuke Sakato 8ae91b9ad8 sh: SH-4A UBC support
A simple patch to enable the UBC on SH-4A.

Signed-off-by: Ryusuke Sakato <sakato@hsdv.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-12 12:16:13 +09:00
Matthew Wilcox e50190a834 [PATCH] Consolidate check_signature
There's nothing arch-specific about check_signature(), so move it to
<linux/io.h>.  Use a cross between the Alpha and i386 implementations as
the generic one.

Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-11 11:14:23 -07:00
Paul Mundt 525ccc452c sh: Convert INTC2 IRQ handler to irq_chip.
More struct irq_chip conversions, this time the INTC2 handlers.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-06 17:35:48 +09:00
Paul Mundt 35f3c5185b sh: Updates for IRQ handler changes.
Trivial fixes for build breakage introduced by IRQ handler changes.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-06 15:31:16 +09:00
Paul Mundt a700f3594d sh: Kill off timer_ops get_frequency().
We're not using this anywhere these days, kill it off.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-06 15:26:21 +09:00
Paul Mundt 4588214526 sh: First step at generic timeofday support.
At the moment we wrap GENERIC_TIME around our existing timer API.
As boards start providing their own clocksources, they're able to
select GENERIC_TIME accordingly and optimize out most of the timer
API.

Once the current timers have been reworked as proper clocksource
drivers, the rest of the place holders for the timer API can go
away and we can flip on GENERIC_TIME unconditionally.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-06 15:26:21 +09:00
Uwe Zeisberger f30c226954 fix file specification in comments
Many files include the filename at the beginning, serveral used a wrong one.

Signed-off-by: Uwe Zeisberger <Uwe_Zeisberger@digi.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-10-03 23:01:26 +02:00
Paul Mundt fac99d9746 sh: Fixup __raw_read_trylock().
generic__raw_read_trylock() was broken, fix up the __raw_read_trylock()
implementation for something sensible. Taken from m32r, which has the
same use cases.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-03 14:13:09 +09:00
Paul Mundt 2914d4da17 sh: Kill off remaining config.h references.
A few of these managed to sneak back in, get rid of them once
and for all.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-03 13:19:02 +09:00
Paul Mundt 3e6c999de9 sh: Initial gitignore list
Ignore build-time generated files.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-03 13:16:15 +09:00
Paul Mundt 711fa80968 sh: build fixes for defconfigs.
Get all of the defconfigs building again.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-03 13:14:04 +09:00
Paul Mundt 059fbd6a5e sh: Kill off more dead headers.
Some old rtc and io headers were left hanging around, kill them off..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-03 13:12:38 +09:00
Arnd Bergmann 135ab6ec8f [PATCH] remove remaining errno and __KERNEL_SYSCALLS__ references
The last in-kernel user of errno is gone, so we should remove the definition
and everything referring to it.  This also removes the now-unused lib/execve.c
file that was introduced earlier.

Also remove every trace of __KERNEL_SYSCALLS__ that still remained in the
kernel.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Hirokazu Takata <takata.hirokazu@renesas.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 07:57:23 -07:00
Serge E. Hallyn 96b644bdec [PATCH] namespaces: utsname: use init_utsname when appropriate
In some places, particularly drivers and __init code, the init utsns is the
appropriate one to use.  This patch replaces those with a the init_utsname
helper.

Changes: Removed several uses of init_utsname().  Hope I picked all the
	right ones in net/ipv4/ipconfig.c.  These are now changed to
	utsname() (the per-process namespace utsname) in the previous
	patch (2/7)

[akpm@osdl.org: CIFS fix]
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Andrey Savochkin <saw@sw.ru>
Cc: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 07:57:21 -07:00
Olaf Hering fb48388337 [PATCH] remove SYSRQ_KEY and related defines from ppc/sh/h8300
Remove unused global SYSRQ_KEY from ppc and powerpc
Remove unused define SYSRQ_KEY from sh/sh64 and h8300
Remove unused pckbd_sysrq_xlate and kbd_sysrq_xlate usage

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:22 -07:00
Martin Schwidefsky ef6edc9746 [PATCH] Directed yield: cpu_relax variants for spinlocks and rw-locks
On systems running with virtual cpus there is optimization potential in
regard to spinlocks and rw-locks.  If the virtual cpu that has taken a lock
is known to a cpu that wants to acquire the same lock it is beneficial to
yield the timeslice of the virtual cpu in favour of the cpu that has the
lock (directed yield).

With CONFIG_PREEMPT="n" this can be implemented by the architecture without
common code changes.  Powerpc already does this.

With CONFIG_PREEMPT="y" the lock loops are coded with _raw_spin_trylock,
_raw_read_trylock and _raw_write_trylock in kernel/spinlock.c.  If the lock
could not be taken cpu_relax is called.  A directed yield is not possible
because cpu_relax doesn't know anything about the lock.  To be able to
yield the lock in favour of the current lock holder variants of cpu_relax
for spinlocks and rw-locks are needed.  The new _raw_spin_relax,
_raw_read_relax and _raw_write_relax primitives differ from cpu_relax
insofar that they have an argument: a pointer to the lock structure.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:21 -07:00