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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    c1a3313698
| tree    337a876f72    tree | snapshot
| parent    f5ffd4620a    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: Marcel 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:  Mark Lord <mlord@pobox.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mark Lord 2007-03-06 01:42:03 -08:00 committed by Linus Torvalds
parent 166f60dde0
commit 0de1517e23
1 changed files with 2 additions and 0 deletions
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2
fs/sysfs/dir.c
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@ -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)) {