2 * Out of line spinlock code.
4 * Copyright IBM Corp. 2004, 2006
5 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
8 #include <linux/types.h>
9 #include <linux/module.h>
10 #include <linux/spinlock.h>
11 #include <linux/init.h>
12 #include <linux/smp.h>
15 int spin_retry = 1000;
18 * spin_retry= parameter
20 static int __init spin_retry_setup(char *str)
22 spin_retry = simple_strtoul(str, &str, 0);
25 __setup("spin_retry=", spin_retry_setup);
27 void arch_spin_lock_wait(arch_spinlock_t *lp)
29 unsigned int cpu = SPINLOCK_LOCKVAL;
34 owner = ACCESS_ONCE(lp->lock);
35 /* Try to get the lock if it is free. */
37 if (_raw_compare_and_swap(&lp->lock, 0, cpu))
41 /* Check if the lock owner is running. */
42 if (!smp_vcpu_scheduled(~owner)) {
43 smp_yield_cpu(~owner);
46 /* Loop for a while on the lock value. */
49 owner = ACCESS_ONCE(lp->lock);
50 } while (owner && count-- > 0);
54 * For multiple layers of hypervisors, e.g. z/VM + LPAR
55 * yield the CPU if the lock is still unavailable.
58 smp_yield_cpu(~owner);
61 EXPORT_SYMBOL(arch_spin_lock_wait);
63 void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
65 unsigned int cpu = SPINLOCK_LOCKVAL;
69 local_irq_restore(flags);
71 owner = ACCESS_ONCE(lp->lock);
72 /* Try to get the lock if it is free. */
75 if (_raw_compare_and_swap(&lp->lock, 0, cpu))
77 local_irq_restore(flags);
79 /* Check if the lock owner is running. */
80 if (!smp_vcpu_scheduled(~owner)) {
81 smp_yield_cpu(~owner);
84 /* Loop for a while on the lock value. */
87 owner = ACCESS_ONCE(lp->lock);
88 } while (owner && count-- > 0);
92 * For multiple layers of hypervisors, e.g. z/VM + LPAR
93 * yield the CPU if the lock is still unavailable.
96 smp_yield_cpu(~owner);
99 EXPORT_SYMBOL(arch_spin_lock_wait_flags);
101 void arch_spin_relax(arch_spinlock_t *lp)
103 unsigned int cpu = lp->lock;
105 if (MACHINE_IS_VM || MACHINE_IS_KVM ||
106 !smp_vcpu_scheduled(~cpu))
110 EXPORT_SYMBOL(arch_spin_relax);
112 int arch_spin_trylock_retry(arch_spinlock_t *lp)
116 for (count = spin_retry; count > 0; count--)
117 if (arch_spin_trylock_once(lp))
121 EXPORT_SYMBOL(arch_spin_trylock_retry);
123 void _raw_read_lock_wait(arch_rwlock_t *rw)
126 int count = spin_retry;
133 old = ACCESS_ONCE(rw->lock);
136 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
140 EXPORT_SYMBOL(_raw_read_lock_wait);
142 void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
145 int count = spin_retry;
147 local_irq_restore(flags);
153 old = ACCESS_ONCE(rw->lock);
157 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
159 local_irq_restore(flags);
162 EXPORT_SYMBOL(_raw_read_lock_wait_flags);
164 int _raw_read_trylock_retry(arch_rwlock_t *rw)
167 int count = spin_retry;
169 while (count-- > 0) {
170 old = ACCESS_ONCE(rw->lock);
173 if (_raw_compare_and_swap(&rw->lock, old, old + 1))
178 EXPORT_SYMBOL(_raw_read_trylock_retry);
180 void _raw_write_lock_wait(arch_rwlock_t *rw)
183 int count = spin_retry;
190 old = ACCESS_ONCE(rw->lock);
193 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
197 EXPORT_SYMBOL(_raw_write_lock_wait);
199 void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
202 int count = spin_retry;
204 local_irq_restore(flags);
210 old = ACCESS_ONCE(rw->lock);
214 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
216 local_irq_restore(flags);
219 EXPORT_SYMBOL(_raw_write_lock_wait_flags);
221 int _raw_write_trylock_retry(arch_rwlock_t *rw)
224 int count = spin_retry;
226 while (count-- > 0) {
227 old = ACCESS_ONCE(rw->lock);
230 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
235 EXPORT_SYMBOL(_raw_write_trylock_retry);