[PATCH] bluetooth: 6lowpan: fix delay work init in add_peer_chan()

[PATCH] bluetooth: 6lowpan: fix delay work init in add_peer_chan()

[Michael Scott]

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(-)

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);
 }
 
-- 
2.11.0

Re: [PATCH] bluetooth: 6lowpan: fix delay work init in add_peer_chan()

[Jukka Rissanen]

Hi Michael,

On Tue, 2017-03-28 at 23:10 -0700, Michael Scott wrote:
> 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(-)
> 
> 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);
>  }
>  

Good catch!

Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>


Cheers,
Jukka

Re: [PATCH] bluetooth: 6lowpan: fix delay work init in add_peer_chan()

[Jukka Rissanen]

Hi Michael,

On Tue, 2017-03-28 at 23:10 -0700, Michael Scott wrote:
> 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-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
>  net/bluetooth/6lowpan.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> 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);
>  }
>  

Good catch!

Acked-by: Jukka Rissanen <jukka.rissanen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>


Cheers,
Jukka

Re: [PATCH] bluetooth: 6lowpan: fix delay work init in add_peer_chan()

[Jukka Rissanen]

Hi Michael,

On Tue, 2017-03-28 at 23:10 -0700, Michael Scott wrote:
> 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(-)
> 
> 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);
>  }
>  

Good catch!

Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>


Cheers,
Jukka

Re: [PATCH] bluetooth: 6lowpan: fix delay work init in add_peer_chan()

[Marcel Holtmann]

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