svn commit: r196159 - head/sys/net80211

[Robert Watson]

On Wed, 12 Aug 2009, Sam Leffler wrote:

>  Drain link state event changes posted during vap destroy.  This is a
>  band-aid for the general problem that if_link_state_change can be
>  called between if_detach and if_free leaving a task queued that has
>  been free'd.

FYI to others -- we believe the proper fix should be in the ifnet framework, 
but this change was the lowest-risk way to resolve the problem for 8.0. 
Following the release we'll investigate having the ifnet framework provide 
this protection automatically for drivers.

Robert N M Watson
Computer Laboratory
University of Cambridge


>  Spotted by:	thompsa
>  Reviewed by:	rwatson
>  Approved by:	re (rwatson)
>
> Modified:
>  head/sys/net80211/ieee80211.c
>
> Modified: head/sys/net80211/ieee80211.c
> ==============================================================================
> --- head/sys/net80211/ieee80211.c	Wed Aug 12 21:06:43 2009	(r196158)
> +++ head/sys/net80211/ieee80211.c	Wed Aug 12 21:19:19 2009	(r196159)
> @@ -573,11 +573,13 @@ ieee80211_vap_detach(struct ieee80211vap
>
> 	/*
> 	 * Flush any deferred vap tasks.
> -	 * NB: must be before ether_ifdetach() and removal from ic_vaps list
> 	 */
> 	ieee80211_draintask(ic, &vap->iv_nstate_task);
> 	ieee80211_draintask(ic, &vap->iv_swbmiss_task);
>
> +	/* XXX band-aid until ifnet handles this for us */
> +	taskqueue_drain(taskqueue_swi, &ifp->if_linktask);
> +
> 	IEEE80211_LOCK(ic);
> 	KASSERT(vap->iv_state == IEEE80211_S_INIT , ("vap still running"));
> 	TAILQ_REMOVE(&ic->ic_vaps, vap, iv_next);
>