linux-toradex.git/kernel/spinlock.c, branch v2.6.25-rc2

spinlock: lockbreak cleanup

2008-01-30T12:31:20+00:00

The break_lock data structure and code for spinlocks is quite nasty.
Not only does it double the size of a spinlock but it changes locking to
a potentially less optimal trylock.

Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a
__raw_spin_is_contended that uses the lock data itself to determine whether
there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is
not set.

Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to
decouple it from the spinlock implementation, and make it typesafe (rwlocks
do not have any need_lockbreak sites -- why do they even get bloated up
with that break_lock then?).

Signed-off-by: Nick Piggin 
Signed-off-by: Ingo Molnar 
Signed-off-by: Thomas Gleixner

lockstat: hook into spinlock_t, rwlock_t, rwsem and mutex

2007-07-19T17:04:49+00:00

Call the new lockstat tracking functions from the various lock primitives.

Signed-off-by: Peter Zijlstra 
Acked-by: Ingo Molnar 
Acked-by: Jason Baron 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lockdep: sanitise CONFIG_PROVE_LOCKING

2007-07-19T17:04:49+00:00

Ensure that all of the lock dependency tracking code is under
CONFIG_PROVE_LOCKING.  This allows us to use the held lock tracking code for
other purposes.

Signed-off-by: Peter Zijlstra 
Acked-by: Ingo Molnar 
Acked-by: Jason Baron 
Signed-off-by: Andrew Morton 
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] Directed yield: cpu_relax variants for spinlocks and rw-locks

2006-10-01T07:39:21+00:00

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 
Cc: Ingo Molnar 
Cc: Paul Mackerras 
Cc: Haavard Skinnemoen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] remove generic__raw_read_trylock()

2006-09-29T16:18:03+00:00

If the cpu has the lock held for write, is interrupted, and the interrupt
handler calls read_trylock(), it's an instant deadlock.

Now, Dave Miller has subsequently pointed out that we don't have any
situations where this can occur.  Nevertheless, we should delete
generic__raw_read_lock (and its associated EXPORT to make Arjan happy) so that
nobody thinks they can use it.

Acked-by: "David S. Miller" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] i386: Account spinlocks to the caller during profiling for !FP kernels

2006-09-26T08:52:28+00:00

This ports the algorithm from x86-64 (with improvements) to i386.
Previously this only worked for frame pointer enabled kernels.
But spinlocks have a very simple stack frame that can be manually
analyzed. Do this.

Signed-off-by: Andi Kleen

[PATCH] lockdep ifdef fix

2006-09-06T18:00:01+00:00

With

	CONFIG_SMP=y
	CONFIG_PREEMPT=y
	CONFIG_LOCKDEP=y
	CONFIG_DEBUG_LOCK_ALLOC=y
	# CONFIG_PROVE_LOCKING is not set

spin_unlock_irqrestore() goes through lockdep but spin_lock_irqsave() doesn't.
Apparently, bad things happen.

Acked-by: 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

Remove obsolete #include

2006-06-30T17:25:36+00:00

Signed-off-by: Jörn Engel 
Signed-off-by: Adrian Bunk