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/*
*
* linux/lib/brlock.c
*
* 'Big Reader' read-write spinlocks. See linux/brlock.h for details.
*
* Copyright 2000, Ingo Molnar <mingo@redhat.com>
* Copyright 2000, David S. Miller <davem@redhat.com>
*/
#include <linux/config.h>
#ifdef CONFIG_SMP
#include <linux/sched.h>
#include <linux/brlock.h>
#ifdef __BRLOCK_USE_ATOMICS
brlock_read_lock_t __brlock_array[NR_CPUS][__BR_IDX_MAX] =
{ [0 ... NR_CPUS-1] = { [0 ... __BR_IDX_MAX-1] = RW_LOCK_UNLOCKED } };
void __br_write_lock (enum brlock_indices idx)
{
int i;
for (i = 0; i < smp_num_cpus; i++)
write_lock(&__brlock_array[cpu_logical_map(i)][idx]);
}
void __br_write_unlock (enum brlock_indices idx)
{
int i;
for (i = 0; i < smp_num_cpus; i++)
write_unlock(&__brlock_array[cpu_logical_map(i)][idx]);
}
#else /* ! __BRLOCK_USE_ATOMICS */
brlock_read_lock_t __brlock_array[NR_CPUS][__BR_IDX_MAX] =
{ [0 ... NR_CPUS-1] = { [0 ... __BR_IDX_MAX-1] = 0 } };
struct br_wrlock __br_write_locks[__BR_IDX_MAX] =
{ [0 ... __BR_IDX_MAX-1] = { SPIN_LOCK_UNLOCKED } };
void __br_write_lock (enum brlock_indices idx)
{
int i;
again:
spin_lock(&__br_write_locks[idx].lock);
for (i = 0; i < smp_num_cpus; i++)
if (__brlock_array[cpu_logical_map(i)][idx] != 0) {
spin_unlock(&__br_write_locks[idx].lock);
barrier();
cpu_relax();
goto again;
}
}
void __br_write_unlock (enum brlock_indices idx)
{
spin_unlock(&__br_write_locks[idx].lock);
}
#endif /* __BRLOCK_USE_ATOMICS */
#endif /* CONFIG_SMP */
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