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s390/spinlock: fix system hang with spin_retry <= 0 

On LPAR, when spin_retry is set to <= 0, arch_spin_lock_wait() and
arch_spin_lock_wait_flags() may end up in a while(1) loop w/o doing
any compare and swap operation. To fix this, use do/while instead of
for loop.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
hifive-unleashed-5.1
Gerald Schaefer 2014-05-06 19:41:36 +02:00 committed by Martin Schwidefsky
parent f1a8582068
commit 2e4006b34d
1 changed files with 8 additions and 6 deletions
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14
arch/s390/lib/spinlock.c
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@ -26,19 +26,20 @@ __setup("spin_retry=", spin_retry_setup);
void arch_spin_lock_wait(arch_spinlock_t *lp)
{
int count = spin_retry;
unsigned int cpu = SPINLOCK_LOCKVAL;
unsigned int owner;
int count;
while (1) {
owner = lp->lock;
if (!owner || smp_vcpu_scheduled(~owner)) {
for (count = spin_retry; count > 0; count--) {
count = spin_retry;
do {
if (arch_spin_is_locked(lp))
continue;
if (_raw_compare_and_swap(&lp->lock, 0, cpu))
return;
}
} while (count-- > 0);
if (MACHINE_IS_LPAR)
continue;
}
@ -53,22 +54,23 @@ EXPORT_SYMBOL(arch_spin_lock_wait);
void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
{
int count = spin_retry;
unsigned int cpu = SPINLOCK_LOCKVAL;
unsigned int owner;
int count;
local_irq_restore(flags);
while (1) {
owner = lp->lock;
if (!owner || smp_vcpu_scheduled(~owner)) {
for (count = spin_retry; count > 0; count--) {
count = spin_retry;
do {
if (arch_spin_is_locked(lp))
continue;
local_irq_disable();
if (_raw_compare_and_swap(&lp->lock, 0, cpu))
return;
local_irq_restore(flags);
}
} while (count-- > 0);
if (MACHINE_IS_LPAR)
continue;
}