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Subject: Re: Oops with commit 6d18c73 bridge: start hello_timer when enabling
 KERNEL_STP in br_stp_start
To: Sebastian Ott <sebott@linux.vnet.ibm.com>,
        Xin Long <lucien.xin@gmail.com>
References: <alpine.LFD.2.20.1705311816090.1727@schleppi>
 <CADvbK_c_bXnPL5NdADj=aCv8f-A0wPKdUmQJqm=XDRf0rizXcA@mail.gmail.com>
 <alpine.LFD.2.20.1706011415500.1688@schleppi>
 <a6495939-350d-31a4-88db-852344a19a02@cumulusnetworks.com>
Cc: "David S. Miller" <davem@davemloft.net>, Haidong Li <haili@redhat.com>,
        Ivan Vecera <cera@cera.cz>,
        Stephen Hemminger <stephen@networkplumber.org>,
        network dev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>
From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Message-ID: <edd9b7f0-0345-975e-dc97-d5261134c7b4@cumulusnetworks.com>
Date: Thu, 1 Jun 2017 17:16:23 +0300
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On 01/06/17 17:00, Nikolay Aleksandrov wrote:
> 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@linux.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);
>  	}
>  
> 

Ah nevermind, this patch reverts it back to the previous state.