From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753528AbdH1IMm (ORCPT ); Mon, 28 Aug 2017 04:12:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34312 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751333AbdH1IMk (ORCPT ); Mon, 28 Aug 2017 04:12:40 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jeffy Chen , Brian Norris , AL Yu-Chen Cho , Marcel Holtmann , Jiri Slaby Subject: [PATCH 4.9 65/84] Bluetooth: cmtp: fix possible might sleep error in cmtp_session Date: Mon, 28 Aug 2017 10:05:30 +0200 Message-Id: <20170828080532.095123010@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170828080529.526391781@linuxfoundation.org> References: <20170828080529.526391781@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeffy Chen commit f06d977309d09253c744e54e75c5295ecc52b7b4 upstream. It looks like cmtp_session has same pattern as the issue reported in old rfcomm: while (1) { set_current_state(TASK_INTERRUPTIBLE); if (condition) break; // may call might_sleep here schedule(); } __set_current_state(TASK_RUNNING); Which fixed at: dfb2fae Bluetooth: Fix nested sleeps So let's fix it at the same way, also follow the suggestion of: https://lwn.net/Articles/628628/ Signed-off-by: Jeffy Chen Reviewed-by: Brian Norris Reviewed-by: AL Yu-Chen Cho Signed-off-by: Marcel Holtmann Cc: Jiri Slaby Signed-off-by: Greg Kroah-Hartman --- net/bluetooth/cmtp/core.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/net/bluetooth/cmtp/core.c +++ b/net/bluetooth/cmtp/core.c @@ -280,16 +280,16 @@ static int cmtp_session(void *arg) struct cmtp_session *session = arg; struct sock *sk = session->sock->sk; struct sk_buff *skb; - wait_queue_t wait; + DEFINE_WAIT_FUNC(wait, woken_wake_function); BT_DBG("session %p", session); set_user_nice(current, -15); - init_waitqueue_entry(&wait, current); add_wait_queue(sk_sleep(sk), &wait); while (1) { - set_current_state(TASK_INTERRUPTIBLE); + /* Ensure session->terminate is updated */ + smp_mb__before_atomic(); if (atomic_read(&session->terminate)) break; @@ -306,9 +306,8 @@ static int cmtp_session(void *arg) cmtp_process_transmit(session); - schedule(); + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } - __set_current_state(TASK_RUNNING); remove_wait_queue(sk_sleep(sk), &wait); down_write(&cmtp_session_sem); @@ -393,7 +392,7 @@ int cmtp_add_connection(struct cmtp_conn err = cmtp_attach_device(session); if (err < 0) { atomic_inc(&session->terminate); - wake_up_process(session->task); + wake_up_interruptible(sk_sleep(session->sock->sk)); up_write(&cmtp_session_sem); return err; } @@ -431,7 +430,11 @@ int cmtp_del_connection(struct cmtp_conn /* Stop session thread */ atomic_inc(&session->terminate); - wake_up_process(session->task); + + /* Ensure session->terminate is updated */ + smp_mb__after_atomic(); + + wake_up_interruptible(sk_sleep(session->sock->sk)); } else err = -ENOENT;