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Commit 470ada6b authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/spinlock: refactor arch_spin_lock_wait[_flags] 



Reorder the spinlock wait code to make it more readable.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 939c5ae4

arch/s390/lib/spinlock.c

+47 −34
Original line number Diff line number Diff line
@@ -31,23 +31,31 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) 
	int count;



	while (1) {

		owner = lp->lock;

		if (!owner || smp_vcpu_scheduled(~owner)) {

			count = spin_retry;

			do {

				if (arch_spin_is_locked(lp))

					continue;

		owner = ACCESS_ONCE(lp->lock);

		/* Try to get the lock if it is free. */

		if (!owner) {

			if (_raw_compare_and_swap(&lp->lock, 0, cpu))

				return;

			} while (count-- > 0);

			if (MACHINE_IS_LPAR)

			continue;

		}

		owner = lp->lock;

		if (owner)

		/* Check if the lock owner is running. */

		if (!smp_vcpu_scheduled(~owner)) {

			smp_yield_cpu(~owner);

			continue;

		}

		/* Loop for a while on the lock value. */

		count = spin_retry;

		do {

			owner = ACCESS_ONCE(lp->lock);

		} while (owner && count-- > 0);

		if (!owner)

			continue;

		/*

		 * For multiple layers of hypervisors, e.g. z/VM + LPAR

		 * yield the CPU if the lock is still unavailable.

		 */

		if (!MACHINE_IS_LPAR)

			smp_yield_cpu(~owner);

		if (_raw_compare_and_swap(&lp->lock, 0, cpu))

			return;

	}

}

EXPORT_SYMBOL(arch_spin_lock_wait);
@@ -60,27 +68,32 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) 


	local_irq_restore(flags);

	while (1) {

		owner = lp->lock;

		if (!owner || smp_vcpu_scheduled(~owner)) {

			count = spin_retry;

			do {

				if (arch_spin_is_locked(lp))

					continue;

		owner = ACCESS_ONCE(lp->lock);

		/* Try to get the lock if it is free. */

		if (!owner) {

			local_irq_disable();

			if (_raw_compare_and_swap(&lp->lock, 0, cpu))

				return;

			local_irq_restore(flags);

			} while (count-- > 0);

			if (MACHINE_IS_LPAR)

		}

		/* Check if the lock owner is running. */

		if (!smp_vcpu_scheduled(~owner)) {

			smp_yield_cpu(~owner);

			continue;

		}

		owner = lp->lock;

		if (owner)

		/* Loop for a while on the lock value. */

		count = spin_retry;

		do {

			owner = ACCESS_ONCE(lp->lock);

		} while (owner && count-- > 0);

		if (!owner)

			continue;

		/*

		 * For multiple layers of hypervisors, e.g. z/VM + LPAR

		 * yield the CPU if the lock is still unavailable.

		 */

		if (!MACHINE_IS_LPAR)

			smp_yield_cpu(~owner);

		local_irq_disable();

		if (_raw_compare_and_swap(&lp->lock, 0, cpu))

			return;

		local_irq_restore(flags);

	}

}

EXPORT_SYMBOL(arch_spin_lock_wait_flags);