[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: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

11 files changed, 31 insertions, 31 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 665db84a1f9f..188365c79204 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -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);
         }
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index cb0cd3cf3b5a..33f71520b89c 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -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;
 }
 
diff --git a/kernel/kthread.c b/kernel/kthread.c
index e377e2244103..f50f174e92da 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -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;
diff --git a/kernel/profile.c b/kernel/profile.c
index a38fa70075fe..a66be468c422 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -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;
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 88b306c4e841..f5cc1cec0fb4 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -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 */
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index c39ed70af174..6116b25aa7cf 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -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();
diff --git a/kernel/sys.c b/kernel/sys.c
index 462d78d55895..df2ddcc6863b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -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);
diff --git a/kernel/timer.c b/kernel/timer.c
index ecb3d67c0e14..207aa4f0aa10 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -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;
diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c
index 21f0db2c9711..40ffde940a86 100644
--- a/lib/rwsem-spinlock.c
+++ b/lib/rwsem-spinlock.c
@@ -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);
diff --git a/lib/rwsem.c b/lib/rwsem.c
index 7644089ec8fa..62fa4eba9ffe 100644
--- a/lib/rwsem.c
+++ b/lib/rwsem.c
@@ -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);
diff --git a/mm/mempool.c b/mm/mempool.c
index e9a0a6337b21..c9f3d4620428 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -229,7 +229,7 @@ repeat_alloc:
         /* 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) {