linux-kernel - Re: Oops with commit 6d18c73 bridge: start hello_timer when enabling KERNEL_STP in br_stp

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Date:   Thu, 1 Jun 2017 17:00:53 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Sebastian Ott <sebott@...ux.vnet.ibm.com>,
        Xin Long <lucien.xin@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Haidong Li <haili@...hat.com>, Ivan Vecera <cera@...a.cz>,
        Stephen Hemminger <stephen@...workplumber.org>,
        network dev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: Oops with commit 6d18c73 bridge: start hello_timer when enabling
 KERNEL_STP in br_stp_start

On 01/06/17 15:34, Sebastian Ott wrote:
> On Thu, 1 Jun 2017, Xin Long wrote:
>> On Thu, Jun 1, 2017 at 12:32 AM, Sebastian Ott
>> <sebott@...ux.vnet.ibm.com> wrote:
>>> [...]
>> 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.
> 
> 
>> 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);
 	}