rfkill: use killable locks instead of interruptible

Apparently, many applications don't expect to get EAGAIN from fd read/write
operations, since POSIX doesn't mandate it.

Use mutex_lock_killable instead of mutex_lock_interruptible, which won't
cause issues.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/rfkill/rfkill.c

@@ -431,8 +431,9 @@ static ssize_t rfkill_state_store(struct device *dev,
 	    state != RFKILL_STATE_SOFT_BLOCKED)
 		return -EINVAL;
 
-	if (mutex_lock_interruptible(&rfkill->mutex))
-		return -ERESTARTSYS;
+	error = mutex_lock_killable(&rfkill->mutex);
+	if (error)
+		return error;
 	error = rfkill_toggle_radio(rfkill, state, 0);
 	mutex_unlock(&rfkill->mutex);
 
@@ -472,7 +473,7 @@ static ssize_t rfkill_claim_store(struct device *dev,
 	 * Take the global lock to make sure the kernel is not in
 	 * the middle of rfkill_switch_all
 	 */
-	error = mutex_lock_interruptible(&rfkill_global_mutex);
+	error = mutex_lock_killable(&rfkill_global_mutex);
 	if (error)
 		return error;