Hi!

> From: Linus Lüssing <[email protected]>
> 
> commit e2d4a80f93fcfaf72e2e20daf6a28e39c3b90677 upstream.

> This patch fixes this issue by re-checking if mpath is about to be
> free'd and if so bails out of re-arming the timer.

> --- a/net/mac80211/mesh_hwmp.c
> +++ b/net/mac80211/mesh_hwmp.c
> @@ -1088,7 +1088,14 @@ void mesh_path_start_discovery(struct ie
>       mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr, ifmsh->sn,
>                              target_flags, mpath->dst, mpath->sn, da, 0,
>                              ttl, lifetime, 0, ifmsh->preq_id++, sdata);
> +
> +     spin_lock_bh(&mpath->state_lock);
> +     if (mpath->flags & MESH_PATH_DELETED) {
> +             spin_unlock_bh(&mpath->state_lock);
> +             goto enddiscovery;
> +     }
>       mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
> +     spin_unlock_bh(&mpath->state_lock);
>  
>  enddiscovery:
>       rcu_read_unlock();

This made brain freeze for a while. AFAICT it can be rewritten as:

 +     spin_lock_bh(&mpath->state_lock);
 +     if (!(mpath->flags & MESH_PATH_DELETED))
               mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
 +     spin_unlock_bh(&mpath->state_lock);

...?

Best regards,
                                                                Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) 
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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