From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:41302 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754259AbeCRQAM (ORCPT ); Sun, 18 Mar 2018 12:00:12 -0400 Subject: Patch "Bluetooth: 6lowpan: fix delay work init in add_peer_chan()" has been added to the 4.9-stable tree To: michael.scott@linaro.org, alexander.levin@microsoft.com, gregkh@linuxfoundation.org, jukka.rissanen@linux.intel.com, marcel@holtmann.org Cc: , From: Date: Sun, 18 Mar 2018 16:59:36 +0100 Message-ID: <152138877652183@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled Bluetooth: 6lowpan: fix delay work init in add_peer_chan() to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bluetooth-6lowpan-fix-delay-work-init-in-add_peer_chan.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Sun Mar 18 16:55:33 CET 2018 From: Michael Scott Date: Tue, 28 Mar 2017 23:10:54 -0700 Subject: Bluetooth: 6lowpan: fix delay work init in add_peer_chan() From: Michael Scott [ Upstream commit d2891c4d071d807f01cc911dc42a68f4568d65cf ] When adding 6lowpan devices very rapidly we sometimes see a crash: [23122.306615] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.9.0-43-arm64 #1 Debian 4.9.9.linaro.43-1 [23122.315400] Hardware name: HiKey Development Board (DT) [23122.320623] task: ffff800075443080 task.stack: ffff800075484000 [23122.326551] PC is at expire_timers+0x70/0x150 [23122.330907] LR is at run_timer_softirq+0xa0/0x1a0 [23122.335616] pc : [] lr : [] pstate: 600001c5 This was due to add_peer_chan() unconditionally initializing the lowpan_btle_dev->notify_peers delayed work structure, even if the lowpan_btle_dev passed into add_peer_chan() had previously been initialized. Normally, this would go unnoticed as the delayed work timer is set for 100 msec, however when calling add_peer_chan() faster than 100 msec it clears out a previously queued delay work causing the crash above. To fix this, let add_peer_chan() know when a new lowpan_btle_dev is passed in so that it only performs the delay work initialization when needed. Signed-off-by: Michael Scott Acked-by: Jukka Rissanen Signed-off-by: Marcel Holtmann Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/bluetooth/6lowpan.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/net/bluetooth/6lowpan.c +++ b/net/bluetooth/6lowpan.c @@ -755,7 +755,8 @@ static void set_ip_addr_bits(u8 addr_typ } static struct l2cap_chan *add_peer_chan(struct l2cap_chan *chan, - struct lowpan_btle_dev *dev) + struct lowpan_btle_dev *dev, + bool new_netdev) { struct lowpan_peer *peer; @@ -786,7 +787,8 @@ static struct l2cap_chan *add_peer_chan( spin_unlock(&devices_lock); /* Notifying peers about us needs to be done without locks held */ - INIT_DELAYED_WORK(&dev->notify_peers, do_notify_peers); + if (new_netdev) + INIT_DELAYED_WORK(&dev->notify_peers, do_notify_peers); schedule_delayed_work(&dev->notify_peers, msecs_to_jiffies(100)); return peer->chan; @@ -843,6 +845,7 @@ out: static inline void chan_ready_cb(struct l2cap_chan *chan) { struct lowpan_btle_dev *dev; + bool new_netdev = false; dev = lookup_dev(chan->conn); @@ -853,12 +856,13 @@ static inline void chan_ready_cb(struct l2cap_chan_del(chan, -ENOENT); return; } + new_netdev = true; } if (!try_module_get(THIS_MODULE)) return; - add_peer_chan(chan, dev); + add_peer_chan(chan, dev, new_netdev); ifup(dev->netdev); } Patches currently in stable-queue which might be from michael.scott@linaro.org are queue-4.9/bluetooth-6lowpan-fix-delay-work-init-in-add_peer_chan.patch