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	Mon, 19 Apr 2010 01:57:37 -0400
Subject: Re: [RFC PATCH] mac80211: Prevent running sta_cleanup timer
 unnecessarily
From: Johannes Berg <johannes@sipsolutions.net>
To: Juuso Oikarinen <juuso.oikarinen@nokia.com>
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Date: Mon, 19 Apr 2010 07:57:24 +0200
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On Mon, 2010-04-19 at 07:56 +0300, Juuso Oikarinen wrote:

> > > --- a/net/mac80211/tx.c
> > > +++ b/net/mac80211/tx.c
> > > @@ -429,6 +429,7 @@ ieee80211_tx_h_unicast_ps_buf(struct ieee80211_tx_data *tx)
> > >  	struct sta_info *sta = tx->sta;
> > >  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
> > >  	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
> > > +	struct ieee80211_local *local = tx->local;
> > >  	u32 staflags;
> > >  
> > >  	if (unlikely(!sta ||
> > > @@ -476,6 +477,12 @@ ieee80211_tx_h_unicast_ps_buf(struct ieee80211_tx_data *tx)
> > >  		info->control.vif = &tx->sdata->vif;
> > >  		info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
> > >  		skb_queue_tail(&sta->ps_tx_buf, tx->skb);
> > > +
> > > +		if (!timer_pending(&local->sta_cleanup))
> > > +			mod_timer(&local->sta_cleanup,
> > > +				  round_jiffies(jiffies +
> > > +						STA_INFO_CLEANUP_INTERVAL));
> > > +
> > 
> > Why bother to check !timer_pending?
> > 
> 
> Otherwise, if we have some periodic TX going on with an interval less
> than STA_INFO_CLEANUP_INTERVAL, the sta_cleanup could be delayed
> considerably.

Ok, makes sense, I didn't check the context there.

johannes