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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

fs/buffer.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

	}

ipc/mqueue.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

}

kernel/kthread.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

kernel/profile.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

kernel/ptrace.c

+1 −1
Original line number Diff line number Diff line
@@ -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 */