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[S390] do local_irq_restore while spinning in spin_lock_irqsave.

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In s390's spin_lock_irqsave, interrupts remain disabled while
spinning. In other architectures like x86 and powerpc, interrupts are
re-enabled while spinning if IRQ is not masked before spin_lock_irqsave
is called.

The following patch re-enables interrupts through local_irq_restore
while spinning for a lock acquisition.
This can improve system response.

[heiko.carstens@de.ibm.com: removed saving of pc]

Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Hisashi Hifumi 2008-01-26 14:11:28 +01:00 committed by Martin Schwidefsky
parent dab5209cd8
commit 894cdde26b
2 changed files with 35 additions and 1 deletions
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23
arch/s390/lib/spinlock.c
View file

@ -59,6 +59,29 @@ void _raw_spin_lock_wait(raw_spinlock_t *lp)
}
EXPORT_SYMBOL(_raw_spin_lock_wait);
void _raw_spin_lock_wait_flags(raw_spinlock_t *lp, unsigned long flags)
{
int count = spin_retry;
unsigned int cpu = ~smp_processor_id();
local_irq_restore(flags);
while (1) {
if (count-- <= 0) {
unsigned int owner = lp->owner_cpu;
if (owner != 0)
_raw_yield_cpu(~owner);
count = spin_retry;
}
if (__raw_spin_is_locked(lp))
continue;
local_irq_disable();
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
return;
local_irq_restore(flags);
}
}
EXPORT_SYMBOL(_raw_spin_lock_wait_flags);
int _raw_spin_trylock_retry(raw_spinlock_t *lp)
{
unsigned int cpu = ~smp_processor_id();

13
include/asm-s390/spinlock.h
View file

@ -53,12 +53,12 @@ _raw_compare_and_swap(volatile unsigned int *lock,
*/
#define __raw_spin_is_locked(x) ((x)->owner_cpu != 0)
#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
#define __raw_spin_unlock_wait(lock) \
do { while (__raw_spin_is_locked(lock)) \
_raw_spin_relax(lock); } while (0)
extern void _raw_spin_lock_wait(raw_spinlock_t *);
extern void _raw_spin_lock_wait_flags(raw_spinlock_t *, unsigned long flags);
extern int _raw_spin_trylock_retry(raw_spinlock_t *);
extern void _raw_spin_relax(raw_spinlock_t *lock);
@ -72,6 +72,17 @@ static inline void __raw_spin_lock(raw_spinlock_t *lp)
_raw_spin_lock_wait(lp);
}
static inline void __raw_spin_lock_flags(raw_spinlock_t *lp,
unsigned long flags)
{
int old;
old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
if (likely(old == 0))
return;
_raw_spin_lock_wait_flags(lp, flags);
}
static inline int __raw_spin_trylock(raw_spinlock_t *lp)
{
int old;