Release 4.13 arch/s390/lib/spinlock.c

/*
 *    Out of line spinlock code.
 *
 *    Copyright IBM Corp. 2004, 2006
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#include <linux/types.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <asm/io.h>


int spin_retry = -1;



static int __init spin_retry_init(void)
{
	if (spin_retry < 0)
		spin_retry = 1000;
	return 0;
}
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early_initcall(spin_retry_init);

/**
 * spin_retry= parameter
 */


static int __init spin_retry_setup(char *str)
{
	spin_retry = simple_strtoul(str, &str, 0);
	return 1;
}
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__setup("spin_retry=", spin_retry_setup);



void arch_spin_lock_wait(arch_spinlock_t *lp)
{
	int cpu = SPINLOCK_LOCKVAL;
	int owner, count, first_diag;

	first_diag = 1;
	while (1) {
		owner = ACCESS_ONCE(lp->lock);
		/* Try to get the lock if it is free. */
		if (!owner) {
			if (__atomic_cmpxchg_bool(&lp->lock, 0, cpu))
				return;
			continue;
		}
		/* First iteration: check if the lock owner is running. */
		if (first_diag && arch_vcpu_is_preempted(~owner)) {
			smp_yield_cpu(~owner);
			first_diag = 0;
			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 unconditionally. For LPAR rely on the
                 * sense running status.
                 */
		if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner)) {
			smp_yield_cpu(~owner);
			first_diag = 0;
		}
	}
}
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22.76%
2
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Philipp Hachtmann
3
2.07%
2
15.38%
Christian Bornträger
2
1.38%
1
7.69%
Thomas Gleixner
2
1.38%
2
15.38%
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13
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EXPORT_SYMBOL(arch_spin_lock_wait);



void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
{
	int cpu = SPINLOCK_LOCKVAL;
	int owner, count, first_diag;

	local_irq_restore(flags);
	first_diag = 1;
	while (1) {
		owner = ACCESS_ONCE(lp->lock);
		/* Try to get the lock if it is free. */
		if (!owner) {
			local_irq_disable();
			if (__atomic_cmpxchg_bool(&lp->lock, 0, cpu))
				return;
			local_irq_restore(flags);
			continue;
		}
		/* Check if the lock owner is running. */
		if (first_diag && arch_vcpu_is_preempted(~owner)) {
			smp_yield_cpu(~owner);
			first_diag = 0;
			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 unconditionally. For LPAR rely on the
                 * sense running status.
                 */
		if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner)) {
			smp_yield_cpu(~owner);
			first_diag = 0;
		}
	}
}
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Hisashi Hifumi
53
32.72%
1
8.33%
Gerald Schaefer
30
18.52%
2
16.67%
Philipp Hachtmann
4
2.47%
2
16.67%
Christian Bornträger
2
1.23%
1
8.33%
Thomas Gleixner
2
1.23%
2
16.67%
Heiko Carstens
1
0.62%
1
8.33%
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162
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12
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EXPORT_SYMBOL(arch_spin_lock_wait_flags);



int arch_spin_trylock_retry(arch_spinlock_t *lp)
{
	int cpu = SPINLOCK_LOCKVAL;
	int owner, count;

	for (count = spin_retry; count > 0; count--) {
		owner = READ_ONCE(lp->lock);
		/* Try to get the lock if it is free. */
		if (!owner) {
			if (__atomic_cmpxchg_bool(&lp->lock, 0, cpu))
				return 1;
		}
	}
	return 0;
}
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Philipp Hachtmann
8
11.27%
1
14.29%
Christian Ehrhardt
2
2.82%
1
14.29%
Christian Bornträger
1
1.41%
1
14.29%
Total
71
100.00%
7
100.00%


EXPORT_SYMBOL(arch_spin_trylock_retry);



void _raw_read_lock_wait(arch_rwlock_t *rw)
{
	int count = spin_retry;
	int owner, old;

#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
	__RAW_LOCK(&rw->lock, -1, __RAW_OP_ADD);
#endif
	owner = 0;
	while (1) {
		if (count-- <= 0) {
			if (owner && arch_vcpu_is_preempted(~owner))
				smp_yield_cpu(~owner);
			count = spin_retry;
		}
		old = ACCESS_ONCE(rw->lock);
		owner = ACCESS_ONCE(rw->owner);
		if (old < 0)
			continue;
		if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
			return;
	}
}
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0.85%
1
12.50%
Thomas Gleixner
1
0.85%
1
12.50%
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8
100.00%


EXPORT_SYMBOL(_raw_read_lock_wait);



int _raw_read_trylock_retry(arch_rwlock_t *rw)
{
	int count = spin_retry;
	int old;

	while (count-- > 0) {
		old = ACCESS_ONCE(rw->lock);
		if (old < 0)
			continue;
		if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
			return 1;
	}
	return 0;
}
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1.56%
1
20.00%
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64
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5
100.00%


EXPORT_SYMBOL(_raw_read_trylock_retry);

#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES



void _raw_write_lock_wait(arch_rwlock_t *rw, int prev)
{
	int count = spin_retry;
	int owner, old;

	owner = 0;
	while (1) {
		if (count-- <= 0) {
			if (owner && arch_vcpu_is_preempted(~owner))
				smp_yield_cpu(~owner);
			count = spin_retry;
		}
		old = ACCESS_ONCE(rw->lock);
		owner = ACCESS_ONCE(rw->owner);
		smp_mb();
		if (old >= 0) {
			prev = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR);
			old = prev;
		}
		if ((old & 0x7fffffff) == 0 && prev >= 0)
			break;
	}
}
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EXPORT_SYMBOL(_raw_write_lock_wait);

#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */



void _raw_write_lock_wait(arch_rwlock_t *rw)
{
	int count = spin_retry;
	int owner, old, prev;

	prev = 0x80000000;
	owner = 0;
	while (1) {
		if (count-- <= 0) {
			if (owner && arch_vcpu_is_preempted(~owner))
				smp_yield_cpu(~owner);
			count = spin_retry;
		}
		old = ACCESS_ONCE(rw->lock);
		owner = ACCESS_ONCE(rw->owner);
		if (old >= 0 &&
		    __atomic_cmpxchg_bool(&rw->lock, old, old | 0x80000000))
			prev = old;
		else
			smp_mb();
		if ((old & 0x7fffffff) == 0 && prev >= 0)
			break;
	}
}
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3
2.40%
1
10.00%
Christian Bornträger
2
1.60%
2
20.00%
Thomas Gleixner
1
0.80%
1
10.00%
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10
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EXPORT_SYMBOL(_raw_write_lock_wait);

#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */



int _raw_write_trylock_retry(arch_rwlock_t *rw)
{
	int count = spin_retry;
	int old;

	while (count-- > 0) {
		old = ACCESS_ONCE(rw->lock);
		if (old)
			continue;
		if (__atomic_cmpxchg_bool(&rw->lock, 0, 0x80000000))
			return 1;
	}
	return 0;
}
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Martin Schwidefsky
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4
66.67%
Christian Ehrhardt
7
11.67%
1
16.67%
Thomas Gleixner
1
1.67%
1
16.67%
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60
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100.00%


EXPORT_SYMBOL(_raw_write_trylock_retry);



void arch_lock_relax(int cpu)
{
	if (!cpu)
		return;
	if (MACHINE_IS_LPAR && !arch_vcpu_is_preempted(~cpu))
		return;
	smp_yield_cpu(~cpu);
}
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3.12%
1
33.33%
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32
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3
100.00%


EXPORT_SYMBOL(arch_lock_relax);
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44.44%
Gerald Schaefer
63
6.06%
2
7.41%
Hisashi Hifumi
57
5.48%
1
3.70%
Philipp Hachtmann
15
1.44%
2
7.41%
Christian Ehrhardt
12
1.15%
1
3.70%
Christian Bornträger
11
1.06%
3
11.11%
Thomas Gleixner
11
1.06%
3
11.11%
Heiko Carstens
2
0.19%
2
7.41%
Paul Gortmaker
1
0.10%
1
3.70%
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Directory: arch/s390/lib

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