Re: Suspicious RCU usage in bridge with Linux v4.0-9362-g1fc149933fd4

[poma <pomidorabelisima@gmail.com>]

On 11.05.2015 16:53, Eric Dumazet wrote:
> On Mon, 2015-05-11 at 15:15 +0200, Dominick Grift wrote:
>> On Mon, May 04, 2015 at 02:35:27PM -0700, Cong Wang wrote:
>>
>> <snip>
>>
>>> It _looks like_ we only retrieve vlan info to fill netlink
>>> messages in timer context, so it doesn't seem we need to
>>> hold br->lock here.
>>>
>>> But I never look into br vlan code of course.
>>
>> This is just a friendly reminder that this issue still exits in: 4.1.0-0.rc2.git3.1
>>
>> Ignore me if you are aware of the above
>>
> 
> Hi Dominick
> 
> Have you tried this patch I sent last monday ?
> 

https://bugzilla.kernel.org/show_bug.cgi?id=98081#c2


> I will submit formally when I get a test result.
> 
> Thanks
> 
> diff --git a/net/bridge/br_stp_timer.c b/net/bridge/br_stp_timer.c
> index 4fcaa67750fda845ad0a180332c4cd96a9524086..7caf7fae2d5b8aa369b924e1c87a47c343fb8954 100644
> --- a/net/bridge/br_stp_timer.c
> +++ b/net/bridge/br_stp_timer.c
> @@ -97,7 +97,9 @@ static void br_forward_delay_timer_expired(unsigned long arg)
>  		netif_carrier_on(br->dev);
>  	}
>  	br_log_state(p);
> +	rcu_read_lock();
>  	br_ifinfo_notify(RTM_NEWLINK, p);
> +	rcu_read_unlock();
>  	spin_unlock(&br->lock);
>  }
>  
> 
> 
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