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b43: Fix lockdep splat
authorLarry Finger <Larry.Finger@lwfinger.net>
Sun, 12 Jan 2014 21:11:37 +0000 (15:11 -0600)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 6 Feb 2014 19:08:14 +0000 (11:08 -0800)
commiteeb405fd975fd5b684248d2d9039d685d34fac52
tree206220a6a98447e0c205b782612b006630645212
parent8009d02813a995de606b860fbbe1d1f64c60b853
b43: Fix lockdep splat

commit 09164043f63c947a49797750a09ca1cd7c31108e upstream.

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>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/net/wireless/b43/main.c