[PATCH] iwlwifi: fix oops in iwl3945_led_brightness_set

[Marcin Slusarz <marcin.slusarz@gmail.com>]

fix race between:
ieee80211_open->ieee80211_led_radio->led_trigger_event->led_set_brightness->iwl3945_led_brightness_set
(which assumes that "led->priv" is not NULL)
and
iwl3945_pci_probe->iwl3945_setup_deferred_work->(...)->iwl3945_bg_alive_start->iwl3945_alive_start->iwl3945_led_register->iwl3945_led_register_led
which sets priv field in struct iwl3945_led
after
led->led_dev.brightness_set = iwl3945_led_brightness_set;
(...)
led_classdev_register(device, &led->led_dev);

http://kerneloops.org/guilty.php?guilty=iwl3945_led_brightness_set&version=2.6.25-release&start=1671168&end=1703935&class=oops

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Zhu Yi <yi.zhu@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: John W. Linville <linville@tuxdriver.com>
Cc: linux-wireless@vger.kernel.org
Cc: ipw3945-devel@lists.sourceforge.net
---

Compile tested only. Please review and test on real hardware.

---
 drivers/net/wireless/iwlwifi/iwl-3945-led.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl-3945-led.c b/drivers/net/wireless/iwlwifi/iwl-3945-led.c
index d200d08..9f08568 100644
--- a/drivers/net/wireless/iwlwifi/iwl-3945-led.c
+++ b/drivers/net/wireless/iwlwifi/iwl-3945-led.c
@@ -185,6 +185,8 @@ static void iwl3945_led_brightness_set(struct led_classdev *led_cdev,
 					       struct iwl3945_led, led_dev);
 	struct iwl3945_priv *priv = led->priv;
 
+	if (!led->registered)
+		return;
 	if (test_bit(STATUS_EXIT_PENDING, &priv->status))
 		return;
 
-- 
1.5.4.5