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Commit Graph

51 Commits

Author SHA1 Message Date
Nobuhiro Iwamatsu
b15ed69166 sh: Fix build alloc_thread_info_node function
By commit b6a84016bd,
alloc_thread_info was replaced by alloc_thread_info_node.
However, the change of the function name and the addition of the argument
were incomplete.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2011-03-24 15:19:14 +09:00
Eric Dumazet
b6a84016bd mm: NUMA aware alloc_thread_info_node()
Add a node parameter to alloc_thread_info(), and change its name to
alloc_thread_info_node()

This change is needed to allow NUMA aware kthread_create_on_cpu()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: David Howells <dhowells@redhat.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-22 17:44:01 -07:00
Paul Mundt
e19553427c Merge branch 'sh/stable-updates'
Conflicts:
	arch/sh/kernel/dwarf.c
	drivers/dma/shdma.c

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2010-04-26 16:08:27 +09:00
Paul Mundt
4a6feab0ee sh: __cpuinit annotate the CPU init path.
All of the regular CPU init path needs to be __cpuinit annotated for CPU
hotplug.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2010-04-21 12:20:42 +09:00
Tejun Heo
5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Paul Mundt
0ea820cf9b sh: Move over to dynamically allocated FPU context.
This follows the x86 xstate changes and implements a task_xstate slab
cache that is dynamically sized to match one of hard FP/soft FP/FPU-less.

This also tidies up and consolidates some of the SH-2A/SH-4 FPU
fragmentation. Now fpu state restorers are commonly defined, with the
init_fpu()/fpu_init() mess reworked to follow the x86 convention.
The fpu_init() register initialization has been replaced by xstate setup
followed by writing out to hardware via the standard restore path.

As init_fpu() now performs a slab allocation a secondary lighterweight
restorer is also introduced for the context switch.

In the future the DSP state will be rolled in here, too.

More work remains for math emulation and the SH-5 FPU, which presently
uses its own special (UP-only) interfaces.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2010-01-13 12:51:40 +09:00
Paul Mundt
a3705799e2 sh: Use SLAB_PANIC for thread_info slab cache.
Presently this has a BUG_ON() for failure cases, as powerpc does. Switch
this over to a SLAB_PANIC instead.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2010-01-12 19:10:06 +09:00
Paul Mundt
cbf6b1ba7a sh: Always provide thread_info allocators.
Presently the thread_info allocators are special cased, depending on
THREAD_SHIFT < PAGE_SHIFT. This provides a sensible definition for them
regardless of configuration, in preparation for extended CPU state.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2010-01-12 19:01:11 +09:00
Paul Mundt
fe51bc9eaf sh: Split out arch/sh/kernel/process.c for _32 and _64 variants.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-01-28 13:18:42 +09:00
Alexey Dobriyan
19c5870c0e Use helpers to obtain task pid in printks (arch code)
One of the easiest things to isolate is the pid printed in kernel log.
There was a patch, that made this for arch-independent code, this one makes
so for arch/xxx files.

It took some time to cross-compile it, but hopefully these are all the
printks in arch code.

Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:43 -07:00
Paul Mundt
836624619b sh: Conditionalize gUSA support.
This conditionalizes gUSA support. gUSA is not supported on
SMP configurations, and it's not necessary there anyways due
to having other atomicity options (ie, movli.l/movco.l).

Anything implementing the LL/SC semantics (all SH-4A CPUs)
can switch to userspace atomicity implementations without
requiring gUSA. This is left default-enabled on all UP so
that glibc doesn't break.

Those that know what they are doing can disable this explicitly.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-09-28 16:04:49 +09:00
Paul Mundt
995bb781d4 sh: Follow gUSA preempt changes in __switch_to().
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-09-28 15:48:06 +09:00
Paul Mundt
e06c4e5775 sh: Fix fs.h removal from mm.h regressions.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-07-31 13:01:43 +09:00
David McCullough
c64ac9f058 sh: fix get_wchan() for SH kernels without framepointers
Do not follow the frame pointers (/proc/X/task/1/stat) unless we were
compiled with them.

Signed-off-by: David McCullough <david_mccullough@au.securecomputing.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-07-26 17:46:07 +09:00
Paul Mundt
357d59469c sh: Tidy up dependencies for SH-2 build.
SH-2 can presently get in to some pretty bogus states, so
we tidy up the dependencies a bit and get it all building
again.

This gets us a bit closer to a functional allyesconfig
and allmodconfig, though there are still a few things to
fix up.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-06-11 15:32:07 +09:00
Paul Mundt
882c12c4e1 sh: Shut up SH2-DSP compile warnings.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-06-08 02:43:37 +00:00
Paul Mundt
e08f457c7c sh: __user annotations for __get/__put_user().
This adds in some more __user annotations. These weren't being
handled properly in some of the __get_user and __put_user paths,
so tidy those up.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-06-08 02:43:36 +00:00
Paul Mundt
f3a9022fd1 sh: sr.bl toggling around idle sleep.
As pointed out by Saito-san, without the sr.bl manipulation we can
occasionally hit delays in the idle loop due to interrupt handling, so
ensure that interrupts are blocked before going to sleep.

At the same time, we throw in TIF_POLLING_NRFLAG for the !hlt_counter
case (primarily used by the ST-40 parts).

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-21 14:34:25 +09:00
Paul Mundt
57be2b484a sh: clockevent/clocksource/hrtimers/nohz TMU support.
This adds basic support for clockevents and clocksources,
presently only implemented for TMU-based systems (which
are the majority of SH-3 and SH-4 systems).

The old NO_IDLE_HZ implementation is also dropped completely,
the only users of this were on TMU-based systems anyways.

More work needs to be done to generalize the TMU handling,
in that the current implementation is rather tied to the
notion of TMU0 and TMU1 utilization.

Additionally, as more SH timers switch over to this scheme,
we'll be able to gut most of the remaining system timer
infrastructure that existed before.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-09 17:33:24 +09:00
Paul Mundt
b118ca572d sh: Convert to common die chain.
This went in immediately after SH added the die chain notifiers,
so move over to that instead..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-09 10:55:38 +09:00
Paul Mundt
53f983a90d sh: Fix PC adjustments for varying opcode length.
There are a few different cases for figuring out how to
size the instruction. We read in the instruction located
at regs->pc - 4 when rewinding the opcode to figure out if
there's a 32-bit opcode before the faulting instruction, with
a default of a - 2 adjustment on a mismatch. In practice this
works for the cases where pc - 4 is just another 16-bit opcode,
or we happen to have a 32-bit and a 16-bit immediately
preceeding the pc value.

In the cases where we aren't rewinding, this is much less ugly..

We also don't bother fixing up the places where we're explicitly
dealing with 16-bit instructions, since this might lead to
confusion regarding the encoding size possibilities on other
CPU variants.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-09 01:35:01 +00:00
Paul Mundt
bd0799977c sh: Support for SH-2A 32-bit opcodes.
SH-2A supports both 16 and 32-bit instructions, add a simple helper
for figuring out the instruction size in the places where there are
hardcoded 16-bit assumptions.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-09 01:35:01 +00:00
Paul Mundt
5f8c9908f2 sh: generic quicklist support.
This moves SH over to the generic quicklists. As per x86_64,
we have special mappings for the PGDs, so these go on their
own list..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-09 01:35:00 +00:00
Paul Mundt
3a2e117e22 sh: Add die chain notifiers.
Add the atomic die chains in, kprobes needs these.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-07 02:11:57 +00:00
Nobuhiro Iwamatsu
9465a54fa4 sh: MS7712SE01 board support.
Support the SH7712 (SH3-DSP) Solution Engine reference board.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-07 02:10:54 +00:00
Hideo Saito
e6bcf562e5 sh: Fix kernel thread stack corruption with preempt.
When I run a preemptive kernel-2.6.20 for SH7780, a created
kthread(pdflush) can not exit by do_exit() in kernel_thread_helper. I
think that the created kthread should have a room for 'struct pt_regs'
space on the stack top, because __switch_to() will refer to the space as
follows using 'regs = task_pt_regs(prev)' and next condition may be true.

Signed-off-by: Hideo Saito <saito@densan.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-03-05 14:13:26 +09:00
Paul Mundt
11c1965687 sh: Fixup cpu_data references for the non-boot CPUs.
There are a lot of bogus cpu_data-> references that only end up working
for the boot CPU, convert these to current_cpu_data to fixup SMP.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-02-13 10:54:45 +09:00
Paul Mundt
aec5e0e1c1 sh: Use a per-cpu ASID cache.
Previously this was implemented using a global cache, cache
this per-CPU instead and bump up the number of context IDs to
match NR_CPUS.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-02-13 10:54:45 +09:00
Paul Mundt
f413d0d9fa sh: Use a jump call table for debug trap handlers.
This rips out most of the needlessly complicated sh_bios and kgdb
trap handling, and forces it all through a common fast dispatch path.
As more debug traps are inserted, it's important to keep them in sync
for all of the parts, not just SH-3/4.

As the SH-2 parts are unable to do traps in the >= 0x40 range, we
restrict the debug traps to the 0x30-0x3f range on all parts, and
also bump the kgdb breakpoint trap down in to this range (from 0xff
to 0x3c) so it's possible to use for nommu.

Optionally, this table can be padded out to catch spurious traps for
SH-3/4, but we don't do that yet..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-02-13 10:54:43 +09:00
Paul Mundt
b652c23cb0 sh: Fix get_wchan().
Some time ago the schedule frame size changed and we failed to reflect
this in get_wchan() at the time. This first popped up as a problem on
SH7751R where schedule_frame ended up being unaligned and generating
an unaligned trap. This fixes it up again..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-12 08:42:08 +09:00
Paul Mundt
dc34d312c7 sh: BUG() handling through trapa vector.
Previously we haven't been doing anything with verbose BUG() reporting,
and we've been relying on the oops path for handling BUG()'s, which is
rather sub-optimal.

This switches BUG handling to use a fixed trapa vector (#0x3e) where we
construct a small bug frame post trapa instruction to get the context
right. This also makes it trivial to wire up a DIE_BUG for the atomic
die chain, which we couldn't really do before.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-12-12 08:42:08 +09:00
Stuart Menefy
f0bc814cfb sh: gcc4 support.
This fixes up the kernel for gcc4. The existing exception handlers
needed some wrapping for pt_regs access, acessing the registers
via a RELOC_HIDE() pointer.

The strcpy() issues popped up here too, so add -ffreestanding and
kill off the symbol export.

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
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
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
Paul Mundt
19f9a34f87 sh: Initial vsyscall page support.
This implements initial support for the vsyscall page on SH.
At the moment we leave it configurable due to having nommu
to support from the same code base. We hook it up for the
signal trampoline return at present, with more to be added
later, once uClibc catches up.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-09-27 18:33:49 +09:00
Paul Mundt
9d549a7d8e sh: Update kexec support for API changes.
This was falling a bit behind..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-09-27 18:26:05 +09:00
Paul Mundt
e5723e0eeb sh: Add support for SH7706/SH7710/SH7343 CPUs.
This adds support for the aforementioned CPU subtypes, and cleans
up some build issues encountered as a result.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-09-27 17:38:11 +09:00
Yoshinori Sato
a2d1a5fae6 sh: __addr_ok() and other misc nommu fixups.
A few more outstanding nommu fixups..

Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-09-27 17:25:07 +09:00
Paul Mundt
2991be7252 sh: Fixup __strnlen_user() behaviour.
Drop TIF_USERSPACE and add addr_limit to the thread_info struct.
Subsequently, use that for address checking in strnlen_user() to
ward off bogus -EFAULTs.

Make __strnlen_user() return 0 on exception, rather than -EFAULT.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-09-27 17:07:07 +09:00
Paul Mundt
b5233d0704 Fix 'make headers_check' on sh
Cleanup for user headers, as noted:

asm-sh/page.h requires asm-generic/memory_model.h, which does not exist in exported headers
asm-sh/ptrace.h requires asm/ubc.h, which does not exist in exported headers

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-09-21 08:36:50 +01:00
Adrian Bunk
cdb0452789 [PATCH] kill include/linux/platform.h, default_idle() cleanup
include/linux/platform.h contained nothing that was actually used except
the default_idle() prototype, and is therefore removed by this patch.

This patch does the following with the platform specific default_idle()
functions on different architectures:
- remove the unused function:
  - parisc
  - sparc64
- make the needlessly global function static:
  - arm
  - h8300
  - m68k
  - m68knommu
  - s390
  - v850
  - x86_64
- add a prototype in asm/system.h:
  - cris
  - i386
  - ia64

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Patrick Mochel <mochel@digitalimplant.org>
Acked-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-24 07:33:21 -08:00
Paul Mundt
a3310bbd3a [PATCH] sh: machine_halt()/machine_power_off() cleanups
machine_halt() managed to trigger the soft lockup detection due to not
disabling interrupts before going to sleep, so correct that.

machine_power_off() should be using pm_power_off, which lets us drop the
board-specific hacks from here.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-01 08:53:20 -08:00
kogiidena
9d44190eae [PATCH] sh: kexec() support
This adds kexec() support for SH.

Signed-off-by: kogiidena <kogiidena@eggplant.ddo.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Cc: <fastboot@lists.osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-16 23:15:27 -08:00
Al Viro
308a792f7c [PATCH] sh: task_stack_page()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-12 09:08:53 -08:00
Al Viro
cafcfcaa60 [PATCH] sh: task_thread_info()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-12 09:08:53 -08:00
Al Viro
3cf0f4ece9 [PATCH] sh: task_pt_regs()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-12 09:08:52 -08:00
akpm@osdl.org
df2e71fb91 [PATCH] dump_thread() cleanup
)

From: Adrian Bunk <bunk@stusta.de>

- create one common dump_thread() prototype in kernel.h

- dump_thread() is only used in fs/binfmt_aout.c and can therefore be
  removed on all architectures where CONFIG_BINFMT_AOUT is not
  available

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:25 -08:00
Nick Piggin
64c7c8f885 [PATCH] sched: resched and cpu_idle rework
Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce
confusion, and make their semantics rigid.  Improves efficiency of
resched_task and some cpu_idle routines.

* In resched_task:
- TIF_NEED_RESCHED is only cleared with the task's runqueue lock held,
  and as we hold it during resched_task, then there is no need for an
  atomic test and set there. The only other time this should be set is
  when the task's quantum expires, in the timer interrupt - this is
  protected against because the rq lock is irq-safe.

- If TIF_NEED_RESCHED is set, then we don't need to do anything. It
  won't get unset until the task get's schedule()d off.

- If we are running on the same CPU as the task we resched, then set
  TIF_NEED_RESCHED and no further action is required.

- If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set
  after TIF_NEED_RESCHED has been set, then we need to send an IPI.

Using these rules, we are able to remove the test and set operation in
resched_task, and make clear the previously vague semantics of
POLLING_NRFLAG.

* In idle routines:
- Enter cpu_idle with preempt disabled. When the need_resched() condition
  becomes true, explicitly call schedule(). This makes things a bit clearer
  (IMO), but haven't updated all architectures yet.

- Many do a test and clear of TIF_NEED_RESCHED for some reason. According
  to the resched_task rules, this isn't needed (and actually breaks the
  assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock
  held). So remove that. Generally one less locked memory op when switching
  to the idle thread.

- Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner
  most polling idle loops. The above resched_task semantics allow it to be
  set until before the last time need_resched() is checked before going into
  a halt requiring interrupt wakeup.

  Many idle routines simply never enter such a halt, and so POLLING_NRFLAG
  can be always left set, completely eliminating resched IPIs when rescheduling
  the idle task.

  POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-09 07:56:33 -08:00
Nick Piggin
5bfb5d690f [PATCH] sched: disable preempt in idle tasks
Run idle threads with preempt disabled.

Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()).
How did it ever work before?

Might fix the CPU hotplugging hang which Nigel Cunningham noted.

We think the bug hits if the idle thread is preempted after checking
need_resched() and before going to sleep, then the CPU offlined.

After calling stop_machine_run, the CPU eventually returns from preemption and
into the idle thread and goes to sleep.  The CPU will continue executing
previous idle and have no chance to call play_dead.

By disabling preemption until we are ready to explicitly schedule, this bug is
fixed and the idle threads generally become more robust.

From: alexs <ashepard@u.washington.edu>

  PPC build fix

From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>

  MIPS build fix

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-09 07:56:33 -08:00
Eric W. Biederman
59586e5a26 [PATCH] Don't export machine_restart, machine_halt, or machine_power_off.
machine_restart, machine_halt and machine_power_off are machine
specific hooks deep into the reboot logic, that modules
have no business messing with.  Usually code should be calling
kernel_restart, kernel_halt, kernel_power_off, or
emergency_restart. So don't export machine_restart,
machine_halt, and machine_power_off so we can catch buggy users.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-26 14:35:42 -07:00