On 01/06/17 15:34, Sebastian Ott wrote:

On Thu, 1 Jun 2017, Xin Long wrote:

quoted

On Thu, Jun 1, 2017 at 12:32 AM, Sebastian Ott
[off-list ref] wrote:

quoted

[...]

I couldn't see any bridge-related thing here, and it couldn't be reproduced
with virbr0 (stp=1) on my box (on both s390x and x86_64), I guess there
is something else in you machine.

With the latest upstream kernel, can you remove libvirt (virbr0) and boot your
machine normally, then:
# brctl addbr br0
# ip link set br0 up
# brctl stp br0 on

to check if it will still hang.

Nope. That doesn't hang.

quoted

If it can't be reproduced in this way, pls add this on your kernel:

--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c

@@ -178,9 +178,11 @@ static void br_stp_start(struct net_bridge *br)
                br->stp_enabled = BR_KERNEL_STP;
                br_debug(br, "using kernel STP\n");

+               WARN_ON(1);
                /* To start timers on any ports left in blocking */
                mod_timer(&br->hello_timer, jiffies + br->hello_time);
                br_port_state_selection(br);
+               pr_warn("hello timer start done\n");
        }

        spin_unlock_bh(&br->lock);

diff --git a/net/bridge/br_stp_timer.c b/net/bridge/br_stp_timer.c
index 60b6fe2..c98b3e5 100644
--- a/net/bridge/br_stp_timer.c
+++ b/net/bridge/br_stp_timer.c

@@ -40,7 +40,7 @@ static void br_hello_timer_expired(unsigned long arg)
        if (br->dev->flags & IFF_UP) {
                br_config_bpdu_generation(br);

-               if (br->stp_enabled == BR_KERNEL_STP)
+               if (br->stp_enabled != BR_USER_STP)
                        mod_timer(&br->hello_timer,
                                  round_jiffies(jiffies + br->hello_time));

let's see if it hangs when starting the timer. Thanks.

No hang either:

[snip]
Could you please try the patch below ?

---

diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 4efd5d54498a..89110319ef0f 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c

@@ -173,7 +173,8 @@ static void br_stp_start(struct net_bridge *br)
 		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);
 	}