Merge branch 'linus' into tracing/mmiotrace

1 files changed, 12 insertions, 1 deletions

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index c3f749abb2d..c9191871c1e 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -566,11 +566,22 @@ static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
 	if (dlc->state == BT_CLOSED) {
 		if (!dev->tty) {
 			if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) {
-				if (rfcomm_dev_get(dev->id) == NULL)
+				/* Drop DLC lock here to avoid deadlock
+				 * 1. rfcomm_dev_get will take rfcomm_dev_lock
+				 *    but in rfcomm_dev_add there's lock order:
+				 *    rfcomm_dev_lock -> dlc lock
+				 * 2. rfcomm_dev_put will deadlock if it's
+				 *    the last reference
+				 */
+				rfcomm_dlc_unlock(dlc);
+				if (rfcomm_dev_get(dev->id) == NULL) {
+					rfcomm_dlc_lock(dlc);
 					return;
+				}
 
 				rfcomm_dev_del(dev);
 				rfcomm_dev_put(dev);
+				rfcomm_dlc_lock(dlc);
 			}
 		} else
 			tty_hangup(dev->tty);