linux.git/arch/sh, branch v2.6.15

[PATCH] sched: resched and cpu_idle rework

2005-11-09T15:56:33+00:00

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 
Cc: Ingo Molnar 
Cc: Con Kolivas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sched: disable preempt in idle tasks

2005-11-09T15:56:33+00:00

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 

  PPC build fix

From: Yoichi Yuasa 

  MIPS build fix

Signed-off-by: Nick Piggin 
Signed-off-by: Yoichi Yuasa 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] consolidate sys_ptrace()

2005-11-07T15:53:42+00:00

The sys_ptrace boilerplate code (everything outside the big switch
statement for the arch-specific requests) is shared by most architectures.
This patch moves it to kernel/ptrace.c and leaves the arch-specific code as
arch_ptrace.

Some architectures have a too different ptrace so we have to exclude them.
They continue to keep their implementations.  For sh64 I had to add a
sh64_ptrace wrapper because it does some initialization on the first call.
For um I removed an ifdefed SUBARCH_PTRACE_SPECIAL block, but
SUBARCH_PTRACE_SPECIAL isn't defined anywhere in the tree.

Signed-off-by: Christoph Hellwig 
Acked-by: Paul Mackerras 
Acked-by: Ralf Baechle 
Acked-By: David Howells 
Acked-by: Russell King 
Acked-by: Paul Mundt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sh: Use pfn_valid() for lazy dcache write-back on SH7705

2005-11-07T15:53:28+00:00

SH7705 in extended cache mode has some left-over VALID_PAGE() cruft that it
checks when doing lazy dcache write-back.  This has been gone for some time
(the last bits were in the discontig code, which should now also be gone --
this also fixes up a build error in the non-discontig case).

pfn_valid() gives the desired behaviour, so we switch to that.

Signed-off-by: Paul Mundt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sh: Drop hp690 discontig support

2005-11-07T15:53:28+00:00

There was only one board using this (hp690 specifically), and it just so
happens that it's only physically discontiguous at the "normal" P1 offset.  If
we bump up the P1 offset, it's possible to hit a shadowed region of memory
where we suddenly become magically contiguous.

As people have been using this shadowed region workaround for quite some time
(and without any adverse effects), it's time to drop the left over discontig
bits that no longer have any practical use (it was always very much
hp690-centric to begin with).

Signed-off-by: Paul Mundt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sh: SuperHyway support for SH4-202

2005-11-07T15:53:28+00:00

This adds support for the relatively quirky (ie, not in line with any known
documentation, and amazed it works at all) SuperHyway implementation on
SH4-202.  This depends on the earlier SuperHyway patch for multiple block
support and VCR refactoring.

Signed-off-by: Paul Mundt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sh: Drop deprecated support for custom ramdisk embedding

2005-11-07T15:53:27+00:00

sh had its own support for embedding ramdisk images in to the kernel binary,
but people are using initramfs for this now, so we drop the ramdisk embedding.

Signed-off-by: Paul Mundt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge master.kernel.org:/home/rmk/linux-2.6-drvmodel

2005-10-31T15:32:56+00:00

Manual #include fixups for clashes - there may be some unnecessary

[PATCH] fix missing includes

2005-10-31T01:37:32+00:00

I recently picked up my older work to remove unnecessary #includes of
sched.h, starting from a patch by Dave Jones to not include sched.h
from module.h. This reduces the number of indirect includes of sched.h
by ~300. Another ~400 pointless direct includes can be removed after
this disentangling (patch to follow later).
However, quite a few indirect includes need to be fixed up for this.

In order to feed the patches through -mm with as little disturbance as
possible, I've split out the fixes I accumulated up to now (complete for
i386 and x86_64, more archs to follow later) and post them before the real
patch.  This way this large part of the patch is kept simple with only
adding #includes, and all hunks are independent of each other.  So if any
hunk rejects or gets in the way of other patches, just drop it.  My scripts
will pick it up again in the next round.

Signed-off-by: Tim Schmielau 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] jiffies_64 cleanup

2005-10-31T01:37:25+00:00

Define jiffies_64 in kernel/timer.c rather than having 24 duplicated
defines in each architecture.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds