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