Re: [PATCH] mac80211: remove ignore_plink_timer flag

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2014-06-04 at 09:27 -0400, Bob Copeland wrote:
> The mesh_plink code is doing some interesting things with the
> ignore_plink_timer flag.  It seems the original intent was to
> handle this race:
> 
> cpu 0                           cpu 1
> -----                           -----
>                                 start timer handler for state X
> acquire sta_lock
> change state from X to Y
> mod_timer() / del_timer()
> release sta_lock
>                                 acquire sta_lock
>                                 execute state Y timer too soon
> 
> However, using the mod_timer()/del_timer() return values to
> detect these cases is broken.  As a result, timers get ignored
> unnecessarily, and stations can get stuck in the peering state
> machine.
> 
> Instead, we can detect the case by looking at the timer expiration.
> In the case of del_timer, just ignore the timers in the following
> (LISTEN/ESTAB) states since they won't have timers anyway.

I'm not entirely sure about the expiration thing - doesn't seem
different from the outside flag? But anyway - applied.

johannes