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Factor out #ifdefs from kernel/spinlock.c to LOCK_CONTENDED_FLAGS

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SGI has observed that on large systems, interrupts are not serviced for a
long period of time when waiting for a rwlock.  The following patch series
re-enables irqs while waiting for the lock, resembling the code which is
already there for spinlocks.

I only made the ia64 version, because the patch adds some overhead to the
fast path.  I assume there is currently no demand to have this for other
architectures, because the systems are not so large.  Of course, the
possibility to implement raw_{read|write}_lock_flags for any architecture
is still there.

This patch:

The new macro LOCK_CONTENDED_FLAGS expands to the correct implementation
depending on the config options, so that IRQ's are re-enabled when
possible, but they remain disabled if CONFIG_LOCKDEP is set.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Robin Holt <holt@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Robin Holt 2009-04-02 16:59:45 -07:00 committed by Linus Torvalds
parent 41d577aa35
commit e8c158bb31
2 changed files with 19 additions and 10 deletions
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17
include/linux/lockdep.h
View File

@ -364,6 +364,23 @@ do { \
#endif /* CONFIG_LOCK_STAT */
#ifdef CONFIG_LOCKDEP
/*
* On lockdep we dont want the hand-coded irq-enable of
* _raw_*_lock_flags() code, because lockdep assumes
* that interrupts are not re-enabled during lock-acquire:
*/
#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
LOCK_CONTENDED((_lock), (try), (lock))
#else /* CONFIG_LOCKDEP */
#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
lockfl((_lock), (flags))
#endif /* CONFIG_LOCKDEP */
#ifdef CONFIG_GENERIC_HARDIRQS
extern void early_init_irq_lock_class(void);
#else

12
kernel/spinlock.c
View File

@ -299,16 +299,8 @@ unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock, int subclas
local_irq_save(flags);
preempt_disable();
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
/*
* On lockdep we dont want the hand-coded irq-enable of
* _raw_spin_lock_flags() code, because lockdep assumes
* that interrupts are not re-enabled during lock-acquire:
*/
#ifdef CONFIG_LOCKDEP
LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
#else
_raw_spin_lock_flags(lock, &flags);
#endif
LOCK_CONTENDED_FLAGS(lock, _raw_spin_trylock, _raw_spin_lock,
_raw_spin_lock_flags, &flags);
return flags;
}
EXPORT_SYMBOL(_spin_lock_irqsave_nested);