Commit d59dd462 authored by akpm@osdl.org's avatar akpm@osdl.org Committed by Linus Torvalds
Browse files

[PATCH] use smp_mb/wmb/rmb where possible



Replace a number of memory barriers with smp_ variants.  This means we won't
take the unnecessary hit on UP machines.
Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 0d8d4d42
......@@ -218,7 +218,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
sb = get_super(bdev);
if (sb && !(sb->s_flags & MS_RDONLY)) {
sb->s_frozen = SB_FREEZE_WRITE;
wmb();
smp_wmb();
sync_inodes_sb(sb, 0);
DQUOT_SYNC(sb);
......@@ -235,7 +235,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
sync_inodes_sb(sb, 1);
sb->s_frozen = SB_FREEZE_TRANS;
wmb();
smp_wmb();
sync_blockdev(sb->s_bdev);
......@@ -263,7 +263,7 @@ void thaw_bdev(struct block_device *bdev, struct super_block *sb)
if (sb->s_op->unlockfs)
sb->s_op->unlockfs(sb);
sb->s_frozen = SB_UNFROZEN;
wmb();
smp_wmb();
wake_up(&sb->s_wait_unfrozen);
drop_super(sb);
}
......
......@@ -767,7 +767,7 @@ static inline void pipelined_send(struct mqueue_inode_info *info,
list_del(&receiver->list);
receiver->state = STATE_PENDING;
wake_up_process(receiver->task);
wmb();
smp_wmb();
receiver->state = STATE_READY;
}
......@@ -786,7 +786,7 @@ static inline void pipelined_receive(struct mqueue_inode_info *info)
list_del(&sender->list);
sender->state = STATE_PENDING;
wake_up_process(sender->task);
wmb();
smp_wmb();
sender->state = STATE_READY;
}
......
......@@ -174,7 +174,7 @@ int kthread_stop(struct task_struct *k)
/* Must init completion *before* thread sees kthread_stop_info.k */
init_completion(&kthread_stop_info.done);
wmb();
smp_wmb();
/* Now set kthread_should_stop() to true, and wake it up. */
kthread_stop_info.k = k;
......
......@@ -522,7 +522,7 @@ static int __init create_hash_tables(void)
return 0;
out_cleanup:
prof_on = 0;
mb();
smp_mb();
on_each_cpu(profile_nop, NULL, 0, 1);
for_each_online_cpu(cpu) {
struct page *page;
......
......@@ -135,7 +135,7 @@ int ptrace_attach(struct task_struct *task)
(current->gid != task->sgid) ||
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
goto bad;
rmb();
smp_rmb();
if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
goto bad;
/* the same process cannot be attached many times */
......
......@@ -33,7 +33,7 @@ static int stopmachine(void *cpu)
set_cpus_allowed(current, cpumask_of_cpu((int)(long)cpu));
/* Ack: we are alive */
mb(); /* Theoretically the ack = 0 might not be on this CPU yet. */
smp_mb(); /* Theoretically the ack = 0 might not be on this CPU yet. */
atomic_inc(&stopmachine_thread_ack);
/* Simple state machine */
......@@ -43,14 +43,14 @@ static int stopmachine(void *cpu)
local_irq_disable();
irqs_disabled = 1;
/* Ack: irqs disabled. */
mb(); /* Must read state first. */
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
} else if (stopmachine_state == STOPMACHINE_PREPARE
&& !prepared) {
/* Everyone is in place, hold CPU. */
preempt_disable();
prepared = 1;
mb(); /* Must read state first. */
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
}
/* Yield in first stage: migration threads need to
......@@ -62,7 +62,7 @@ static int stopmachine(void *cpu)
}
/* Ack: we are exiting. */
mb(); /* Must read state first. */
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
if (irqs_disabled)
......@@ -77,7 +77,7 @@ static int stopmachine(void *cpu)
static void stopmachine_set_state(enum stopmachine_state state)
{
atomic_set(&stopmachine_thread_ack, 0);
wmb();
smp_wmb();
stopmachine_state = state;
while (atomic_read(&stopmachine_thread_ack) != stopmachine_num_threads)
cpu_relax();
......
......@@ -525,7 +525,7 @@ asmlinkage long sys_setregid(gid_t rgid, gid_t egid)
if (new_egid != old_egid)
{
current->mm->dumpable = 0;
wmb();
smp_wmb();
}
if (rgid != (gid_t) -1 ||
(egid != (gid_t) -1 && egid != old_rgid))
......@@ -556,7 +556,7 @@ asmlinkage long sys_setgid(gid_t gid)
if(old_egid != gid)
{
current->mm->dumpable=0;
wmb();
smp_wmb();
}
current->gid = current->egid = current->sgid = current->fsgid = gid;
}
......@@ -565,7 +565,7 @@ asmlinkage long sys_setgid(gid_t gid)
if(old_egid != gid)
{
current->mm->dumpable=0;
wmb();
smp_wmb();
}
current->egid = current->fsgid = gid;
}
......@@ -596,7 +596,7 @@ static int set_user(uid_t new_ruid, int dumpclear)
if(dumpclear)
{
current->mm->dumpable = 0;
wmb();
smp_wmb();
}
current->uid = new_ruid;
return 0;
......@@ -653,7 +653,7 @@ asmlinkage long sys_setreuid(uid_t ruid, uid_t euid)
if (new_euid != old_euid)
{
current->mm->dumpable=0;
wmb();
smp_wmb();
}
current->fsuid = current->euid = new_euid;
if (ruid != (uid_t) -1 ||
......@@ -703,7 +703,7 @@ asmlinkage long sys_setuid(uid_t uid)
if (old_euid != uid)
{
current->mm->dumpable = 0;
wmb();
smp_wmb();
}
current->fsuid = current->euid = uid;
current->suid = new_suid;
......@@ -748,7 +748,7 @@ asmlinkage long sys_setresuid(uid_t ruid, uid_t euid, uid_t suid)
if (euid != current->euid)
{
current->mm->dumpable = 0;
wmb();
smp_wmb();
}
current->euid = euid;
}
......@@ -798,7 +798,7 @@ asmlinkage long sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid)
if (egid != current->egid)
{
current->mm->dumpable = 0;
wmb();
smp_wmb();
}
current->egid = egid;
}
......@@ -845,7 +845,7 @@ asmlinkage long sys_setfsuid(uid_t uid)
if (uid != old_fsuid)
{
current->mm->dumpable = 0;
wmb();
smp_wmb();
}
current->fsuid = uid;
}
......@@ -875,7 +875,7 @@ asmlinkage long sys_setfsgid(gid_t gid)
if (gid != old_fsgid)
{
current->mm->dumpable = 0;
wmb();
smp_wmb();
}
current->fsgid = gid;
key_fsgid_changed(current);
......
......@@ -1007,7 +1007,7 @@ asmlinkage long sys_getppid(void)
* Make sure we read the pid before re-reading the
* parent pointer:
*/
rmb();
smp_rmb();
parent = me->group_leader->real_parent;
if (old != parent)
continue;
......
......@@ -76,7 +76,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
list_del(&waiter->list);
tsk = waiter->task;
/* Don't touch waiter after ->task has been NULLed */
mb();
smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
......@@ -91,7 +91,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
list_del(&waiter->list);
tsk = waiter->task;
mb();
smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
......@@ -123,7 +123,7 @@ __rwsem_wake_one_writer(struct rw_semaphore *sem)
list_del(&waiter->list);
tsk = waiter->task;
mb();
smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
......
......@@ -74,7 +74,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int downgrading)
*/
list_del(&waiter->list);
tsk = waiter->task;
mb();
smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
......@@ -117,7 +117,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int downgrading)
waiter = list_entry(next, struct rwsem_waiter, list);
next = waiter->list.next;
tsk = waiter->task;
mb();
smp_mb();
waiter->task = NULL;
wake_up_process(tsk);
put_task_struct(tsk);
......
......@@ -229,7 +229,7 @@ void * mempool_alloc(mempool_t *pool, unsigned int __nocast gfp_mask)
/* Now start performing page reclaim */
gfp_temp = gfp_mask;
prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
mb();
smp_mb();
if (!pool->curr_nr)
io_schedule();
finish_wait(&pool->wait, &wait);
......@@ -250,7 +250,7 @@ void mempool_free(void *element, mempool_t *pool)
{
unsigned long flags;
mb();
smp_mb();
if (pool->curr_nr < pool->min_nr) {
spin_lock_irqsave(&pool->lock, flags);
if (pool->curr_nr < pool->min_nr) {
......
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