linux-kernel - Re: [PATCH] ath9k : Fix ieee80211 work while going to suspend

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Message-ID: <20130321114219.GB1459@redhat.com>
Date:	Thu, 21 Mar 2013 12:42:20 +0100
From:	Stanislaw Gruszka <sgruszka@...hat.com>
To:	"Luis R. Rodriguez" <rodrigue@....qualcomm.com>
Cc:	"John W. Linville" <linville@...driver.com>,
	Parag Warudkar <parag.lkml@...il.com>,
	Jouni Malinen <jouni@....qualcomm.com>,
	Vasanthakumar Thiagarajan <vthiagar@....qualcomm.com>,
	linux-wireless@...r.kernel.org, ath9k-devel@...ema.h4ckr.net,
	netdev@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	senthilb@....qualcomm.com
Subject: Re: [PATCH] ath9k : Fix ieee80211 work while going to suspend

On Mon, Mar 18, 2013 at 02:03:08PM -0700, Luis R. Rodriguez wrote:
> > > --- a/drivers/net/wireless/ath/ath9k/link.c
> > > +++ b/drivers/net/wireless/ath/ath9k/link.c
> > > @@ -158,7 +158,8 @@ void ath_start_rx_poll(struct ath_softc *sc, u8 nbeacon)
> > >  {
> > >   if (!AR_SREV_9300(sc->sc_ah))
> > >   return;
> > > -
> > > + if (sc->suspending)
> > > + return;
> 
> Thanks for the patch! Please note the style issue here, you should
> use a tab, but other than that lets review what happened.
> 
> > >   if (!test_bit(SC_OP_PRIM_STA_VIF, &sc->sc_flags))
> > >   return;
> 
> Note that what this will do is call later mod_timer() for
> rx_poll_timer, the right thing to do then, which would
> be equivalent to your patch is to modify the ath_start_rx_poll()
> to instead use the new API mod_timer_pending() added on v2.6.30
> via commit 74019224. This would not re-arm the timer if it was
> previously removed.
[snip]
> -	mod_timer(&sc->rx_poll_timer, jiffies + msecs_to_jiffies
> -		  (nbeacon * sc->cur_beacon_conf.beacon_interval));
> +	mod_timer_pending(&sc->rx_poll_timer, jiffies + msecs_to_jiffies
> +			  (nbeacon * sc->cur_beacon_conf.beacon_interval));

But isn't this prevent to run timer in case it was not running, but
we want to start it ?

> Looking at this makes me think we should review all usage of
> mod_timer all over our 802.11 drivers, and mac80211, cfg80211 as
> well.

I mac80211 we use local->suspended and local->quiesce booleans to
prevent reschedule of timers when going to suspend for example.
Works use ifmgd->associted to prevent reschedule when we are
disassociating.

I think on ath9k also some boolean variable should be used, not only
for rx_poll_timer but also for other works i.e. tx_complete_work.
Is possible to use SC_OP_INVALID flags, since mac80211 call ath9k_stop
on suspend and ath9k_start on resume.

Stanislaw

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