Re: [PATCH v2] mac80211: Don't restart sta-timer if not associated.

[Ben Greear <greearb@candelatech.com>]

On 03/19/2013 01:21 PM, Johannes Berg wrote:
> On Thu, 2013-03-14 at 17:24 -0700, greearb@candelatech.com wrote:
>> From: Ben Greear <greearb@candelatech.com>
>>
>> I found another crash when deleting lots of virtual stations
>> in a congested environment.  I think the problem is that
>> the ieee80211_mlme_notify_scan_completed could call
>> ieee80211_restart_sta_timer for a non-associated interface
>> that was about to be deleted.
>>
>> With the following patch I am unable to reproduce the
>> crash.
>>
>> Signed-off-by: Ben Greear <greearb@candelatech.com>
>> ---
>> v2:  Be more selective:  Still need to do sdata->work even
>>    if not associated so that we *can* associate.
>>
>> :100644 100644 81e0619... da805e2... M	net/mac80211/mlme.c
>>   net/mac80211/mlme.c |    7 +++++--
>>   1 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
>> index 81e0619..da805e2 100644
>> --- a/net/mac80211/mlme.c
>> +++ b/net/mac80211/mlme.c
>> @@ -2935,11 +2935,14 @@ static void ieee80211_restart_sta_timer(struct ieee80211_sub_if_data *sdata)
>>
>>   		/* let's probe the connection once */
>>   		flags = sdata->local->hw.flags;
>> -		if (!(flags & IEEE80211_HW_CONNECTION_MONITOR))
>> +		if ((!(flags & IEEE80211_HW_CONNECTION_MONITOR)) &&
>> +		    sdata->u.mgd.associated)
>
> You really didn't need those extra parentheses :-)

I like them :)

...never can remember if the ! operator takes
precedence over &&, but can remove them...

>>   			ieee80211_queue_work(&sdata->local->hw,
>>   					     &sdata->u.mgd.monitor_work);
>> +
>>   		/* and do all the other regular work too */
>> -		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
>> +		if (ieee80211_sdata_running(sdata))
>> +			ieee80211_queue_work(&sdata->local->hw, &sdata->work);
>
> Overall, it seems that it would be safe to just check
> ieee80211_sdata_running() in the beginning of the function instead?

I'm not sure.  I can look at the code closer tomorrow perhaps.

> Maybe you could also look at the ibss/mesh code and fix this issue for
> good?

Will poke around in that as well, but I have no way to test it currently.

Ben

>
> johannes
>


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com