linux-toradex.git/include/linux/spinlock.h, branch v2.6.23.12

introduce write_trylock_irqsave()

2007-07-16T16:05:40+00:00

Introduce a write_trylock_irqsave() implementation.  Similar in style to
the implementation of spin_trylock_irqsave() in mainline.

Signed-off-by: Satyam Sharma 
Cc: Sripathi Kodi 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] timer/hrtimer: take per cpu locks in sane order

2007-03-05T15:57:53+00:00

Doing something like this on a two cpu system

  # echo 0 > /sys/devices/system/cpu/cpu0/online
  # echo 1 > /sys/devices/system/cpu/cpu0/online
  # echo 0 > /sys/devices/system/cpu/cpu1/online

will give me this:

  =======================================================
  [ INFO: possible circular locking dependency detected ]
  2.6.21-rc2-g562aa1d4-dirty #7
  -------------------------------------------------------
  bash/1282 is trying to acquire lock:
   (&cpu_base->lock_key){.+..}, at: [<000000000005f17e>] hrtimer_cpu_notify+0xc6/0x240

  but task is already holding lock:
   (&cpu_base->lock_key#2){.+..}, at: [<000000000005f174>] hrtimer_cpu_notify+0xbc/0x240

  which lock already depends on the new lock.

This happens because we have the following code in kernel/hrtimer.c:

  migrate_hrtimers(int cpu)
  [...]
  old_base = &per_cpu(hrtimer_bases, cpu);
  new_base = &get_cpu_var(hrtimer_bases);
  [...]
  spin_lock(&new_base->lock);
  spin_lock(&old_base->lock);

Which means the spinlocks are taken in an order which depends on which cpu
gets shut down from which other cpu. Therefore lockdep complains that there
might be an ABBA deadlock. Since migrate_hrtimers() gets only called on
cpu hotplug it's safe to assume that it isn't executed concurrently on a

The same problem exists in kernel/timer.c: migrate_timers().

As pointed out by Christian Borntraeger one possible solution to avoid
the locking order complaints would be to make sure that the locks are
always taken in the same order. E.g. by taking the lock of the cpu with
the lower number first.

To achieve this we introduce two new spinlock functions double_spin_lock
and double_spin_unlock which lock or unlock two locks in a given order.

Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Roman Zippel 
Cc: John Stultz 
Cc: Christian Borntraeger 
Cc: Martin Schwidefsky 
Signed-off-by: Heiko Carstens 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Fix sparse annotation of spin unlock macros in one case

2007-02-11T19:18:07+00:00

SMP systems without premption and spinlock debugging enabled use unlock
macros that don't tell sparse that the lock is being released.  Add sparse
annotations in this case.

Signed-off-by: Pavel Roskin 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] add bottom_half.h

2006-12-07T16:39:20+00:00

With CONFIG_SMP=n:

  drivers/input/ff-memless.c:384: warning: implicit declaration of function 'local_bh_disable'
  drivers/input/ff-memless.c:393: warning: implicit declaration of function 'local_bh_enable'

Really linux/spinlock.h should include linux/interrupt.h.  But interrupt.h
includes sched.h which will need spinlock.h.

So the patch breaks the _bh declarations out into a separate header and
includes it in both interrupt.h and spinlock.h.

Cc: "Randy.Dunlap" 
Cc: Andi Kleen 
Cc: 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Revert "[PATCH] Enforce "unsigned long flags;" when spinlocking"

2006-11-27T00:27:17+00:00

This reverts commit ee3ce191e8eaa4cc15c51a28b34143b36404c4f5, since it
broke on at least ARM, MIPS and PA-RISC due to complicated header file
dependencies.

Conflicts in include/linux/spinlock.h (due to the "nested" variety
fixes) fixed up by hand.

Cc: Alexey Dobriyan 
Cc: Ralf Baechle 
Cc: Kyle McMartin 
Cc: Russell King 
Signed-off-by: Linus Torvalds

[PATCH] lockdep: spin_lock_irqsave_nested()

2006-11-25T21:28:34+00:00

Introduce spin_lock_irqsave_nested(); implementation from:
 http://lkml.org/lkml/2006/6/1/122
Patch from:
 http://lkml.org/lkml/2006/9/13/258

[akpm@osdl.org: two compile fixes]
Signed-off-by: Arjan van de Ven 
Signed-off-by: Jiri Kosina 
Signed-off-by: Peter Zijlstra 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Enforce "unsigned long flags;" when spinlocking

2006-11-25T21:28:34+00:00

Make it break or warn if you pass to spin_lock_irqsave() and friends
something different from "unsigned long flags;".  Suprisingly large amount
of these was caught by recent commit
c53421b18f205c5f97c604ae55c6a921f034b0f6 and others.

Idea is largely from FRV typechecking. Suggestions from Andrew Morton.
All stupid typos in first version fixed.

Passes allmodconfig on i386, x86_64, alpha, arm as well as my usual config.

Note #1: checking with sparse is still needed, because a driver can save
	 and pass around flags or something. So far patch is very intrusive.
Note #2: techically, we should break only if
		sizeof(flags) < sizeof(unsigned long),
	 however, the more pain for getting suspicious code into kernel,
	 the better.

Signed-off-by: Alexey Dobriyan 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Pass a lock expression to __cond_lock, like acquire and release

2006-09-29T16:18:20+00:00

Currently, __acquire and __release take a lock expression, but __cond_lock
takes only a condition, not the lock acquired if the expression evaluates
to true.  Change __cond_lock to accept a lock expression, and change all
the callers to pass in a lock expression.

Signed-off-by: Josh Triplett 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Replace _spin_trylock with spin_trylock in the IRQ variants to use __cond_lock

2006-09-29T16:18:19+00:00

spin_trylock_irq and spin_trylock_irqsave use _spin_trylock, which does not
use the __cond_lock wrapper annotation and thus does not affect the lock
context; change them to use spin_trylock instead, which does use
__cond_lock.

Signed-off-by: Josh Triplett 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] lockdep: prove spinlock rwlock locking correctness

2006-07-03T22:27:04+00:00

Use the lock validator framework to prove spinlock and rwlock locking
correctness.

Signed-off-by: Ingo Molnar 
Signed-off-by: Arjan van de Ven 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds