/* * * 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_ATOMICSbrlock_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 */