| Message ID | 20170329061054.4300-1-michael.scott@linaro.org |
|---|---|
| State | New |
| Headers | show |
Hi Michael, > 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> > --- > net/bluetooth/6lowpan.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) patch has been applied to bluetooth-next tree. Regards Marcel
diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c index e27be3ca0a0c..c282482edc2c 100644 --- a/net/bluetooth/6lowpan.c +++ b/net/bluetooth/6lowpan.c @@ -754,7 +754,8 @@ static void set_ip_addr_bits(u8 addr_type, u8 *addr) } 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; @@ -785,7 +786,8 @@ static struct l2cap_chan *add_peer_chan(struct l2cap_chan *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; @@ -842,6 +844,7 @@ static int setup_netdev(struct l2cap_chan *chan, struct lowpan_btle_dev **dev) static inline void chan_ready_cb(struct l2cap_chan *chan) { struct lowpan_btle_dev *dev; + bool new_netdev = false; dev = lookup_dev(chan->conn); @@ -852,12 +855,13 @@ static inline void chan_ready_cb(struct l2cap_chan *chan) 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); }
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> --- net/bluetooth/6lowpan.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) -- 2.11.0