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>
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@ -26,19 +26,20 @@ __setup("spin_retry=", spin_retry_setup);
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void arch_spin_lock_wait(arch_spinlock_t *lp)
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{
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int count = spin_retry;
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unsigned int cpu = SPINLOCK_LOCKVAL;
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unsigned int owner;
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int count;
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while (1) {
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owner = lp->lock;
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if (!owner || smp_vcpu_scheduled(~owner)) {
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for (count = spin_retry; count > 0; count--) {
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count = spin_retry;
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do {
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if (arch_spin_is_locked(lp))
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continue;
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if (_raw_compare_and_swap(&lp->lock, 0, cpu))
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return;
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}
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} while (count-- > 0);
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if (MACHINE_IS_LPAR)
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continue;
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}
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@ -53,22 +54,23 @@ EXPORT_SYMBOL(arch_spin_lock_wait);
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void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
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{
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int count = spin_retry;
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unsigned int cpu = SPINLOCK_LOCKVAL;
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unsigned int owner;
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int count;
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local_irq_restore(flags);
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while (1) {
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owner = lp->lock;
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if (!owner || smp_vcpu_scheduled(~owner)) {
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for (count = spin_retry; count > 0; count--) {
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count = spin_retry;
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do {
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if (arch_spin_is_locked(lp))
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continue;
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local_irq_disable();
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if (_raw_compare_and_swap(&lp->lock, 0, cpu))
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return;
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local_irq_restore(flags);
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}
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} while (count-- > 0);
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if (MACHINE_IS_LPAR)
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continue;
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}
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