wl12xx: Fix potential interrupt storm

The interrupt threaded handler exits immediately if the driver's state
is WL1271_STATE_OFF. As a result, the interrupt status is not read. If
the interrupt is level triggered, it will be fired again.

Fix this by disabling interrupts before setting the state to OFF.

Signed-off-by: Ido Yariv <ido@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c
index 9e9fb3f..3a1636b 100644 (file)
--- a/drivers/net/wireless/wl12xx/main.c
+++ b/drivers/net/wireless/wl12xx/main.c
@@ -1397,9 +1397,23 @@ int wl1271_plt_stop(struct wl1271 *wl)
 
        wl1271_notice("power down");
 
+       /*
+        * Interrupts must be disabled before setting the state to OFF.
+        * Otherwise, the interrupt handler might be called and exit without
+        * reading the interrupt status.
+        */
+       wl1271_disable_interrupts(wl);
        mutex_lock(&wl->mutex);
        if (wl->state != WL1271_STATE_PLT) {
                mutex_unlock(&wl->mutex);
+
+               /*
+                * This will not necessarily enable interrupts as interrupts
+                * may have been disabled when op_stop was called. It will,
+                * however, balance the above call to disable_interrupts().
+                */
+               wl1271_enable_interrupts(wl);
+
                wl1271_error("cannot power down because not in PLT "
                             "state: %d", wl->state);
                ret = -EBUSY;
@@ -1411,7 +1425,6 @@ int wl1271_plt_stop(struct wl1271 *wl)
 
        mutex_unlock(&wl->mutex);
 
-       wl1271_disable_interrupts(wl);
        wl1271_flush_deferred_work(wl);
        cancel_work_sync(&wl->netstack_work);
        cancel_work_sync(&wl->recovery_work);
@@ -1773,11 +1786,25 @@ static void wl1271_op_stop(struct ieee80211_hw *hw)
 
        wl1271_debug(DEBUG_MAC80211, "mac80211 stop");
 
+       /*
+        * Interrupts must be disabled before setting the state to OFF.
+        * Otherwise, the interrupt handler might be called and exit without
+        * reading the interrupt status.
+        */
+       wl1271_disable_interrupts(wl);
        mutex_lock(&wl->mutex);
        if (wl->state == WL1271_STATE_OFF) {
                mutex_unlock(&wl->mutex);
+
+               /*
+                * This will not necessarily enable interrupts as interrupts
+                * may have been disabled when op_stop was called. It will,
+                * however, balance the above call to disable_interrupts().
+                */
+               wl1271_enable_interrupts(wl);
                return;
        }
+
        /*
         * this must be before the cancel_work calls below, so that the work
         * functions don't perform further work.
@@ -1789,7 +1816,6 @@ static void wl1271_op_stop(struct ieee80211_hw *hw)
        list_del(&wl->list);
        mutex_unlock(&wl_list_mutex);
 
-       wl1271_disable_interrupts(wl);
        wl1271_flush_deferred_work(wl);
        cancel_delayed_work_sync(&wl->scan_complete_work);
        cancel_work_sync(&wl->netstack_work);