b43: Fix lockdep splat
authorLarry Finger <Larry.Finger@lwfinger.net>
Sun, 12 Jan 2014 21:11:37 +0000 (15:11 -0600)
committerJohn W. Linville <linville@tuxdriver.com>
Mon, 13 Jan 2014 19:50:02 +0000 (14:50 -0500)
commit09164043f63c947a49797750a09ca1cd7c31108e
tree5c21741cd96bb16df0c54c063b010c324b94248c
parent9795229752c31da0c5f8a7dc4c827665327b52f9
b43: Fix lockdep splat

In https://bugzilla.kernel.org/show_bug.cgi?id=67561, a locking dependency is reported
when b43 is used with hostapd, and rfkill is used to kill the radio output.

The lockdep splat (in part) is as follows:

======================================================
[ INFO: possible circular locking dependency detected ]
3.12.0 #1 Not tainted
-------------------------------------------------------
rfkill/10040 is trying to acquire lock:
 (rtnl_mutex){+.+.+.}, at: [<ffffffff8146f282>] rtnl_lock+0x12/0x20

but task is already holding lock:
 (rfkill_global_mutex){+.+.+.}, at: [<ffffffffa04832ca>] rfkill_fop_write+0x6a/0x170 [rfkill]

--snip--

Chain exists of:
  rtnl_mutex --> misc_mtx --> rfkill_global_mutex

The fix is to move the initialization of the hardware random number generator
outside the code range covered by the rtnl_mutex.

Reported-by: yury <urykhy@gmail.com>
Tested-by: yury <urykhy@gmail.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
drivers/net/wireless/b43/main.c