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[PATCH] use smp_mb/wmb/rmb where possible

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Replace a number of memory barriers with smp_ variants.  This means we won't
take the unnecessary hit on UP machines.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
akpm@osdl.org 2005-05-01 08:58:47 -07:00 committed by Linus Torvalds
parent 0d8d4d42f2
commit d59dd4620f
11 changed files with 31 additions and 31 deletions
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6
fs/buffer.c
View file

@ -218,7 +218,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
sb = get_super(bdev); sb = get_super(bdev);
if (sb && !(sb->s_flags & MS_RDONLY)) { if (sb && !(sb->s_flags & MS_RDONLY)) {
sb->s_frozen = SB_FREEZE_WRITE; sb->s_frozen = SB_FREEZE_WRITE;
wmb(); smp_wmb();
sync_inodes_sb(sb, 0); sync_inodes_sb(sb, 0);
DQUOT_SYNC(sb); DQUOT_SYNC(sb);
@ -235,7 +235,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
sync_inodes_sb(sb, 1); sync_inodes_sb(sb, 1);
sb->s_frozen = SB_FREEZE_TRANS; sb->s_frozen = SB_FREEZE_TRANS;
wmb(); smp_wmb();
sync_blockdev(sb->s_bdev); 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) if (sb->s_op->unlockfs)
sb->s_op->unlockfs(sb); sb->s_op->unlockfs(sb);
sb->s_frozen = SB_UNFROZEN; sb->s_frozen = SB_UNFROZEN;
wmb(); smp_wmb();
wake_up(&sb->s_wait_unfrozen); wake_up(&sb->s_wait_unfrozen);
drop_super(sb); drop_super(sb);
} }

4
ipc/mqueue.c
View file

@ -767,7 +767,7 @@ static inline void pipelined_send(struct mqueue_inode_info *info,
list_del(&receiver->list); list_del(&receiver->list);
receiver->state = STATE_PENDING; receiver->state = STATE_PENDING;
wake_up_process(receiver->task); wake_up_process(receiver->task);
wmb(); smp_wmb();
receiver->state = STATE_READY; receiver->state = STATE_READY;
} }
@ -786,7 +786,7 @@ static inline void pipelined_receive(struct mqueue_inode_info *info)
list_del(&sender->list); list_del(&sender->list);
sender->state = STATE_PENDING; sender->state = STATE_PENDING;
wake_up_process(sender->task); wake_up_process(sender->task);
wmb(); smp_wmb();
sender->state = STATE_READY; sender->state = STATE_READY;
} }

2
kernel/kthread.c
View file

@ -174,7 +174,7 @@ int kthread_stop(struct task_struct *k)
/* Must init completion *before* thread sees kthread_stop_info.k */ /* Must init completion *before* thread sees kthread_stop_info.k */
init_completion(&kthread_stop_info.done); init_completion(&kthread_stop_info.done);
wmb(); smp_wmb();
/* Now set kthread_should_stop() to true, and wake it up. */ /* Now set kthread_should_stop() to true, and wake it up. */
kthread_stop_info.k = k; kthread_stop_info.k = k;

2
kernel/profile.c
View file

@ -522,7 +522,7 @@ static int __init create_hash_tables(void)
return 0; return 0;
out_cleanup: out_cleanup:
prof_on = 0; prof_on = 0;
mb(); smp_mb();
on_each_cpu(profile_nop, NULL, 0, 1); on_each_cpu(profile_nop, NULL, 0, 1);
for_each_online_cpu(cpu) { for_each_online_cpu(cpu) {
struct page *page; struct page *page;

2
kernel/ptrace.c
View file

@ -135,7 +135,7 @@ int ptrace_attach(struct task_struct *task)
(current->gid != task->sgid) || (current->gid != task->sgid) ||
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
goto bad; goto bad;
rmb(); smp_rmb();
if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
goto bad; goto bad;
/* the same process cannot be attached many times */ /* the same process cannot be attached many times */

10
kernel/stop_machine.c
View file

@ -33,7 +33,7 @@ static int stopmachine(void *cpu)
set_cpus_allowed(current, cpumask_of_cpu((int)(long)cpu)); set_cpus_allowed(current, cpumask_of_cpu((int)(long)cpu));
/* Ack: we are alive */ /* 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); atomic_inc(&stopmachine_thread_ack);
/* Simple state machine */ /* Simple state machine */
@ -43,14 +43,14 @@ static int stopmachine(void *cpu)
local_irq_disable(); local_irq_disable();
irqs_disabled = 1; irqs_disabled = 1;
/* Ack: irqs disabled. */ /* Ack: irqs disabled. */
mb(); /* Must read state first. */ smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack); atomic_inc(&stopmachine_thread_ack);
} else if (stopmachine_state == STOPMACHINE_PREPARE } else if (stopmachine_state == STOPMACHINE_PREPARE
&& !prepared) { && !prepared) {
/* Everyone is in place, hold CPU. */ /* Everyone is in place, hold CPU. */
preempt_disable(); preempt_disable();
prepared = 1; prepared = 1;
mb(); /* Must read state first. */ smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack); atomic_inc(&stopmachine_thread_ack);
} }
/* Yield in first stage: migration threads need to /* Yield in first stage: migration threads need to
@ -62,7 +62,7 @@ static int stopmachine(void *cpu)
} }
/* Ack: we are exiting. */ /* Ack: we are exiting. */
mb(); /* Must read state first. */ smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack); atomic_inc(&stopmachine_thread_ack);
if (irqs_disabled) if (irqs_disabled)
@ -77,7 +77,7 @@ static int stopmachine(void *cpu)
static void stopmachine_set_state(enum stopmachine_state state) static void stopmachine_set_state(enum stopmachine_state state)
{ {
atomic_set(&stopmachine_thread_ack, 0); atomic_set(&stopmachine_thread_ack, 0);
wmb(); smp_wmb();
stopmachine_state = state; stopmachine_state = state;
while (atomic_read(&stopmachine_thread_ack) != stopmachine_num_threads) while (atomic_read(&stopmachine_thread_ack) != stopmachine_num_threads)
cpu_relax(); cpu_relax();

20
kernel/sys.c
View file

@ -525,7 +525,7 @@ asmlinkage long sys_setregid(gid_t rgid, gid_t egid)
if (new_egid != old_egid) if (new_egid != old_egid)
{ {
current->mm->dumpable = 0; current->mm->dumpable = 0;
wmb(); smp_wmb();
} }
if (rgid != (gid_t) -1 || if (rgid != (gid_t) -1 ||
(egid != (gid_t) -1 && egid != old_rgid)) (egid != (gid_t) -1 && egid != old_rgid))
@ -556,7 +556,7 @@ asmlinkage long sys_setgid(gid_t gid)
if(old_egid != gid) if(old_egid != gid)
{ {
current->mm->dumpable=0; current->mm->dumpable=0;
wmb(); smp_wmb();
} }
current->gid = current->egid = current->sgid = current->fsgid = gid; current->gid = current->egid = current->sgid = current->fsgid = gid;
} }
@ -565,7 +565,7 @@ asmlinkage long sys_setgid(gid_t gid)
if(old_egid != gid) if(old_egid != gid)
{ {
current->mm->dumpable=0; current->mm->dumpable=0;
wmb(); smp_wmb();
} }
current->egid = current->fsgid = gid; current->egid = current->fsgid = gid;
} }
@ -596,7 +596,7 @@ static int set_user(uid_t new_ruid, int dumpclear)
if(dumpclear) if(dumpclear)
{ {
current->mm->dumpable = 0; current->mm->dumpable = 0;
wmb(); smp_wmb();
} }
current->uid = new_ruid; current->uid = new_ruid;
return 0; return 0;
@ -653,7 +653,7 @@ asmlinkage long sys_setreuid(uid_t ruid, uid_t euid)
if (new_euid != old_euid) if (new_euid != old_euid)
{ {
current->mm->dumpable=0; current->mm->dumpable=0;
wmb(); smp_wmb();
} }
current->fsuid = current->euid = new_euid; current->fsuid = current->euid = new_euid;
if (ruid != (uid_t) -1 || if (ruid != (uid_t) -1 ||
@ -703,7 +703,7 @@ asmlinkage long sys_setuid(uid_t uid)
if (old_euid != uid) if (old_euid != uid)
{ {
current->mm->dumpable = 0; current->mm->dumpable = 0;
wmb(); smp_wmb();
} }
current->fsuid = current->euid = uid; current->fsuid = current->euid = uid;
current->suid = new_suid; 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) if (euid != current->euid)
{ {
current->mm->dumpable = 0; current->mm->dumpable = 0;
wmb(); smp_wmb();
} }
current->euid = euid; current->euid = euid;
} }
@ -798,7 +798,7 @@ asmlinkage long sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid)
if (egid != current->egid) if (egid != current->egid)
{ {
current->mm->dumpable = 0; current->mm->dumpable = 0;
wmb(); smp_wmb();
} }
current->egid = egid; current->egid = egid;
} }
@ -845,7 +845,7 @@ asmlinkage long sys_setfsuid(uid_t uid)
if (uid != old_fsuid) if (uid != old_fsuid)
{ {
current->mm->dumpable = 0; current->mm->dumpable = 0;
wmb(); smp_wmb();
} }
current->fsuid = uid; current->fsuid = uid;
} }
@ -875,7 +875,7 @@ asmlinkage long sys_setfsgid(gid_t gid)
if (gid != old_fsgid) if (gid != old_fsgid)
{ {
current->mm->dumpable = 0; current->mm->dumpable = 0;
wmb(); smp_wmb();
} }
current->fsgid = gid; current->fsgid = gid;
key_fsgid_changed(current); key_fsgid_changed(current);

2
kernel/timer.c
View file

@ -1007,7 +1007,7 @@ asmlinkage long sys_getppid(void)
* Make sure we read the pid before re-reading the * Make sure we read the pid before re-reading the
* parent pointer: * parent pointer:
*/ */
rmb(); smp_rmb();
parent = me->group_leader->real_parent; parent = me->group_leader->real_parent;
if (old != parent) if (old != parent)
continue; continue;

6
lib/rwsem-spinlock.c
View file

@ -76,7 +76,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
list_del(&waiter->list); list_del(&waiter->list);
tsk = waiter->task; tsk = waiter->task;
/* Don't touch waiter after ->task has been NULLed */ /* Don't touch waiter after ->task has been NULLed */
mb(); smp_mb();
waiter->task = NULL; waiter->task = NULL;
wake_up_process(tsk); wake_up_process(tsk);
put_task_struct(tsk); put_task_struct(tsk);
@ -91,7 +91,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
list_del(&waiter->list); list_del(&waiter->list);
tsk = waiter->task; tsk = waiter->task;
mb(); smp_mb();
waiter->task = NULL; waiter->task = NULL;
wake_up_process(tsk); wake_up_process(tsk);
put_task_struct(tsk); put_task_struct(tsk);
@ -123,7 +123,7 @@ __rwsem_wake_one_writer(struct rw_semaphore *sem)
list_del(&waiter->list); list_del(&waiter->list);
tsk = waiter->task; tsk = waiter->task;
mb(); smp_mb();
waiter->task = NULL; waiter->task = NULL;
wake_up_process(tsk); wake_up_process(tsk);
put_task_struct(tsk); put_task_struct(tsk);

4
lib/rwsem.c
View file

@ -74,7 +74,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int downgrading)
*/ */
list_del(&waiter->list); list_del(&waiter->list);
tsk = waiter->task; tsk = waiter->task;
mb(); smp_mb();
waiter->task = NULL; waiter->task = NULL;
wake_up_process(tsk); wake_up_process(tsk);
put_task_struct(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); waiter = list_entry(next, struct rwsem_waiter, list);
next = waiter->list.next; next = waiter->list.next;
tsk = waiter->task; tsk = waiter->task;
mb(); smp_mb();
waiter->task = NULL; waiter->task = NULL;
wake_up_process(tsk); wake_up_process(tsk);
put_task_struct(tsk); put_task_struct(tsk);

4
mm/mempool.c
View file

@ -229,7 +229,7 @@ repeat_alloc:
/* Now start performing page reclaim */ /* Now start performing page reclaim */
gfp_temp = gfp_mask; gfp_temp = gfp_mask;
prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE); prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
mb(); smp_mb();
if (!pool->curr_nr) if (!pool->curr_nr)
io_schedule(); io_schedule();
finish_wait(&pool->wait, &wait); finish_wait(&pool->wait, &wait);
@ -250,7 +250,7 @@ void mempool_free(void *element, mempool_t *pool)
{ {
unsigned long flags; unsigned long flags;
mb(); smp_mb();
if (pool->curr_nr < pool->min_nr) { if (pool->curr_nr < pool->min_nr) {
spin_lock_irqsave(&pool->lock, flags); spin_lock_irqsave(&pool->lock, flags);
if (pool->curr_nr < pool->min_nr) { if (pool->curr_nr < pool->min_nr) {