Return-Path: From: Peter Hurley To: linux-bluetooth Date: Fri, 5 Aug 2011 10:44:21 -0400 Subject: [PATCH] Bluetooth: cmtp: Fix deadlock in session deletion Message-ID: <1312555461.2172.5.camel@THOR> Content-Type: text/plain; charset=US-ASCII MIME-Version: 1.0 Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Commit fada4ac339 introduced the usage of kthread API. kthread_stop is a blocking function which returns only when the thread exits. In this case, the thread can't exit because it's waiting for the write lock, which is being held by cmtp_del_connection() which is waiting for the thread to exit -- deadlock. Revert cmtp_reset_ctr to its original behavior: non-blocking signalling for the session to terminate. Signed-off-by: Peter Hurley --- net/bluetooth/cmtp/capi.c | 3 ++- net/bluetooth/cmtp/cmtp.h | 1 + net/bluetooth/cmtp/core.c | 5 +++-- 3 files changed, 6 insertions(+), 3 deletions(-) diff --git a/net/bluetooth/cmtp/capi.c b/net/bluetooth/cmtp/capi.c index 744233c..e080b0d 100644 --- a/net/bluetooth/cmtp/capi.c +++ b/net/bluetooth/cmtp/capi.c @@ -387,7 +387,8 @@ static void cmtp_reset_ctr(struct capi_ctr *ctrl) capi_ctr_down(ctrl); - kthread_stop(session->task); + atomic_inc(&session->terminate); + wake_up_process(session->task); } static void cmtp_register_appl(struct capi_ctr *ctrl, __u16 appl, capi_register_params *rp) diff --git a/net/bluetooth/cmtp/cmtp.h b/net/bluetooth/cmtp/cmtp.h index db43b54..c32638d 100644 --- a/net/bluetooth/cmtp/cmtp.h +++ b/net/bluetooth/cmtp/cmtp.h @@ -81,6 +81,7 @@ struct cmtp_session { char name[BTNAMSIZ]; + atomic_t terminate; struct task_struct *task; wait_queue_head_t wait; diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c index 2eb854a..42cb2f4 100644 --- a/net/bluetooth/cmtp/core.c +++ b/net/bluetooth/cmtp/core.c @@ -295,7 +295,7 @@ static int cmtp_session(void *arg) while (1) { set_current_state(TASK_INTERRUPTIBLE); - if (kthread_should_stop()) + if (atomic_read(&session->terminate)) break; if (sk->sk_state != BT_CONNECTED) break; @@ -416,7 +416,8 @@ int cmtp_del_connection(struct cmtp_conndel_req *req) skb_queue_purge(&session->transmit); /* Stop session thread */ - kthread_stop(session->task); + atomic_inc(&session->terminate); + wake_up_process(session->task); } else err = -ENOENT; -- 1.7.4.1