4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michael Scott michael.scott@linaro.org
[ 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 : [<ffff000008142dd8>] lr : [<ffff000008142f58>] 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 michael.scott@linaro.org Acked-by: Jukka Rissanen jukka.rissanen@linux.intel.com Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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); }