Patch "net: bridge: start hello timer only if device is up" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

net: bridge: start hello timer only if device is up

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:
net-bridge-start-hello-timer-only-if-device-is-up.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 <[email protected]> know about it.

From: Nikolay Aleksandrov <[email protected]>
Date: Thu, 1 Jun 2017 18:07:55 +0300
Subject: net: bridge: start hello timer only if device is up

From: Nikolay Aleksandrov <[email protected]>

[ Upstream commit aeb073241fe7a2b932e04e20c60e47718332877f ]

When the transition of NO_STP -> KERNEL_STP was fixed by always calling mod_timer in br_stp_start, it introduced a new regression which causes the timer to be armed even when the bridge is down, and since we stop the timers in its ndo_stop() function, they never get disabled if the device is destroyed before it's upped.

To reproduce:

$ while :; do ip l add br0 type bridge hello_time 100; brctl stp br0 on;
ip l del br0; done;

---
 net/bridge/br_stp_if.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -185,7 +185,8 @@ static void br_stp_start(struct net_brid
 		br_debug(br, "using kernel STP\n");
 
 		/* To start timers on any ports left in blocking */
-		mod_timer(&br->hello_timer, jiffies + br->hello_time);
+		if (br->dev->flags & IFF_UP)
+			mod_timer(&br->hello_timer, jiffies + br->hello_time);
 		br_port_state_selection(br);
 	}
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/net-bridge-start-hello-timer-only-if-device-is-up.patch