Re: [PATCH] mac80211: Requeue work for all iftypes after scan completion

[Johannes Berg <johannes@sipsolutions.net>]

On Thu, 2014-07-10 at 21:32 +0530, Sachin Kulkarni wrote:
> From: Sachin Kulkarni<sachin.kulkarni@imgtec.com>
> 
> During a hw scan ieee80211_iface_work ignores work items for all vifs. However
> after the scan complete work is requeued only for STA, ADHOC and MESH iftypes.
> This occasionally results in event processing getting delayed for iftype AP when
> it coexists with a STA, and when the scan durations are very long.
> 
> Signed-off-by: Sachin Kulkarni<sachin.kulkarni@imgtec.com>
> Cc: linux-wireless@vger.kernel.org
> Cc: johannes@sipsolutions.net
> ---
> We have a test scenario where there are 2 VIFs: one STA and one AP. The STA is
> not connected to anyone while the AP has a station connected to it. The hardware
> we are using currently has scan durations of ~8 sec and a new scan request is
> generated every 10 s. This results in a window of only 2 s when work items can
> be processed by ieee80211_iface_work. We came across scenarios where the AP is
> trying to tear down a AMPDU session, and the IEEE80211_SDATA_QUEUE_AGG_STOP
> event gets queued. However the work item for this gets ignored by the ieee80211_iface_work
> since a hw scan is in progress most of the time. When the scan completes however
> the work item for the AP does not get requeued, and by the time the
> IEEE80211_SDATA_QUEUE_AGG_STOP gets processed in some other work items context,
> the TX frames just keep getting queued up, since the tid has not been destroyed.
> This results in disconnections since things like ARP timeouts etc start
> happening.
> ---
>   net/mac80211/mlme.c |    5 +++--
>   1 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index 931330b..49af420 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -3647,9 +3647,10 @@ static void ieee80211_restart_sta_timer(struct ieee80211_sub_if_data *sdata)
>   		if (!(flags&  IEEE80211_HW_CONNECTION_MONITOR))
>   			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);
>   	}
> +
> +	/* and do all the other regular work too */
> +	ieee80211_queue_work(&sdata->local->hw,&sdata->work);

Please fix the space while at it. :)

johannes