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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
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@@ -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();