[PATCH 3.4 13/37] b43: Fix lockdep splat

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Larry Finger <Larry.Finger@lwfinger.net>

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 |   17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -2413,6 +2413,7 @@ error:
 
 static int b43_one_core_attach(struct b43_bus_dev *dev, struct b43_wl *wl);
 static void b43_one_core_detach(struct b43_bus_dev *dev);
+static int b43_rng_init(struct b43_wl *wl);
 
 static void b43_request_firmware(struct work_struct *work)
 {
@@ -2459,6 +2460,10 @@ start_ieee80211:
 	if (err)
 		goto err_one_core_detach;
 	b43_leds_register(wl->current_dev);
+
+	/* Register HW RNG driver */
+	b43_rng_init(wl);
+
 	goto out;
 
 err_one_core_detach:
@@ -4583,9 +4588,6 @@ static void b43_wireless_core_exit(struc
 	if (!dev || b43_status(dev) != B43_STAT_INITIALIZED)
 		return;
 
-	/* Unregister HW RNG driver */
-	b43_rng_exit(dev->wl);
-
 	b43_set_status(dev, B43_STAT_UNINIT);
 
 	/* Stop the microcode PSM. */
@@ -4728,9 +4730,6 @@ static int b43_wireless_core_init(struct
 
 	b43_set_status(dev, B43_STAT_INITIALIZED);
 
-	/* Register HW RNG driver */
-	b43_rng_init(dev->wl);
-
 out:
 	return err;
 
@@ -5388,6 +5387,9 @@ static void b43_bcma_remove(struct bcma_
 
 	b43_one_core_detach(wldev->dev);
 
+	/* Unregister HW RNG driver */
+	b43_rng_exit(wl);
+
 	b43_leds_unregister(wl);
 
 	ieee80211_free_hw(wl->hw);
@@ -5468,6 +5470,9 @@ static void b43_ssb_remove(struct ssb_de
 
 	b43_one_core_detach(dev);
 
+	/* Unregister HW RNG driver */
+	b43_rng_exit(wl);
+
 	if (list_empty(&wl->devlist)) {
 		b43_leds_unregister(wl);
 		/* Last core on the chip unregistered.