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Commit 0de1517e authored by Mark Lord's avatar Mark Lord Committed by Linus Torvalds
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[PATCH] Fix 2.6.21 rfcomm lockups 



Any attempt to open/use a bluetooth rfcomm device locks up
scheduling completely on my machine.

Interrupts (ping, alt-sysrq) seem to be alive, but nothing else.

This was working fine in 2.6.20, broken now in 2.6.21-rc2-git*

Reverting this change (below) fixes it:

| author    Marcel Holtmann <marcel@holtmann.org>
|      Sat, 17 Feb 2007 22:58:57 +0000 (23:58 +0100)
| committer    David S. Miller <davem@sunset.davemloft.net>
|      Mon, 26 Feb 2007 19:42:41 +0000 (11:42 -0800)
| commit    c1a33136
| tree    337a876f727061362b6a169f8759849c105b8f7a    tree | snapshot
| parent    f5ffd462    commit | diff
| | [Bluetooth] Make use of device_move() for RFCOMM TTY devices
| | In the case of bound RFCOMM TTY devices the parent is not available
| before its usage. So when opening a RFCOMM TTY device, move it to
| the corresponding ACL device as a child. When closing the device,
| move it back to the virtual device tree.
| Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>

The simplest fix for this bug is to prevent sysfs_move_dir()
from self-deadlocking when (old_parent == new_parent).

This patch prevents total system lockup when using rfcomm devices.

Signed-off-by: default avatarMark Lord <mlord@pobox.com>
Acked-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 166f60dd

fs/sysfs/dir.c

+2 −0
Original line number Diff line number Diff line
@@ -431,6 +431,8 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent) 
	new_parent_dentry = new_parent ?

		new_parent->dentry : sysfs_mount->mnt_sb->s_root;



	if (old_parent_dentry->d_inode == new_parent_dentry->d_inode)

		return 0;	/* nothing to move */

again:

	mutex_lock(&old_parent_dentry->d_inode->i_mutex);

	if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {