[PATCH] lockdep: avoid lockdep warning in md (d63a5a74) · Commits · 戴 / test

md_open takes ->reconfig_mutex which causes lockdep to complain. This (normally) doesn't have deadlock potential as the possible conflict is with a reconfig_mutex in a different device. I say "normally" because if a loop were created in the array->member hierarchy a deadlock could happen. However that causes bigger problems than a deadlock and should be fixed independently. So we flag the lock in md_open as a nested lock. This requires defining mutex_lock_interruptible_nested. Cc: Ingo Molnar <mingo@elte.hu> Acked-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by:

Ingo Molnar <mingo@elte.hu> Signed-off-by:

Neil Brown <neilb@suse.de> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

drivers/md/md.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4423,7 +4423,7 @@ static int md_open(struct inode inode, struct file file)
		mddev_t *mddev = inode->i_bdev->bd_disk->private_data;
		int err;

		if ((err = mddev_lock(mddev)))
		if ((err = mutex_lock_interruptible_nested(&mddev->reconfig_mutex, 1)))
		goto out;

		err = 0;

include/linux/mutex.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -125,8 +125,10 @@ extern int fastcall mutex_lock_interruptible(struct mutex *lock);

		#ifdef CONFIG_DEBUG_LOCK_ALLOC
		extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
		extern int mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass);
		#else
		# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
		# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
		#endif

		/*

kernel/mutex.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -206,6 +206,15 @@ mutex_lock_nested(struct mutex *lock, unsigned int subclass)
		}

		EXPORT_SYMBOL_GPL(mutex_lock_nested);

		int __sched
		mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass)
		{
		might_sleep();
		return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass);
		}

		EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
		#endif

		/*

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