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 int count = spin_retry;
30 unsigned int cpu = ~smp_processor_id();
34 owner = lp->owner_cpu;
35 if (!owner || smp_vcpu_scheduled(~owner)) {
36 for (count = spin_retry; count > 0; count--) {
37 if (arch_spin_is_locked(lp))
39 if (_raw_compare_and_swap(&lp->owner_cpu, 0,
46 owner = lp->owner_cpu;
48 smp_yield_cpu(~owner);
49 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
53 EXPORT_SYMBOL(arch_spin_lock_wait);
55 void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
57 int count = spin_retry;
58 unsigned int cpu = ~smp_processor_id();
61 local_irq_restore(flags);
63 owner = lp->owner_cpu;
64 if (!owner || smp_vcpu_scheduled(~owner)) {
65 for (count = spin_retry; count > 0; count--) {
66 if (arch_spin_is_locked(lp))
69 if (_raw_compare_and_swap(&lp->owner_cpu, 0,
72 local_irq_restore(flags);
77 owner = lp->owner_cpu;
79 smp_yield_cpu(~owner);
81 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
83 local_irq_restore(flags);
86 EXPORT_SYMBOL(arch_spin_lock_wait_flags);
88 int arch_spin_trylock_retry(arch_spinlock_t *lp)
90 unsigned int cpu = ~smp_processor_id();
93 for (count = spin_retry; count > 0; count--) {
94 if (arch_spin_is_locked(lp))
96 if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
101 EXPORT_SYMBOL(arch_spin_trylock_retry);
103 void arch_spin_relax(arch_spinlock_t *lock)
105 unsigned int cpu = lock->owner_cpu;
107 if (MACHINE_IS_VM || MACHINE_IS_KVM ||
108 !smp_vcpu_scheduled(~cpu))
112 EXPORT_SYMBOL(arch_spin_relax);
114 void _raw_read_lock_wait(arch_rwlock_t *rw)
117 int count = spin_retry;
124 if (!arch_read_can_lock(rw))
126 old = rw->lock & 0x7fffffffU;
127 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
131 EXPORT_SYMBOL(_raw_read_lock_wait);
133 void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
136 int count = spin_retry;
138 local_irq_restore(flags);
144 if (!arch_read_can_lock(rw))
146 old = rw->lock & 0x7fffffffU;
148 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
152 EXPORT_SYMBOL(_raw_read_lock_wait_flags);
154 int _raw_read_trylock_retry(arch_rwlock_t *rw)
157 int count = spin_retry;
159 while (count-- > 0) {
160 if (!arch_read_can_lock(rw))
162 old = rw->lock & 0x7fffffffU;
163 if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
168 EXPORT_SYMBOL(_raw_read_trylock_retry);
170 void _raw_write_lock_wait(arch_rwlock_t *rw)
172 int count = spin_retry;
179 if (!arch_write_can_lock(rw))
181 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
185 EXPORT_SYMBOL(_raw_write_lock_wait);
187 void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
189 int count = spin_retry;
191 local_irq_restore(flags);
197 if (!arch_write_can_lock(rw))
200 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
204 EXPORT_SYMBOL(_raw_write_lock_wait_flags);
206 int _raw_write_trylock_retry(arch_rwlock_t *rw)
208 int count = spin_retry;
210 while (count-- > 0) {
211 if (!arch_write_can_lock(rw))
213 if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
218 EXPORT_SYMBOL(_raw_write_trylock_retry);