linux-kernel - Re: [REVERT] be6b38bcb175613f239e0b302607db346472c6b6. v2.6.34-rc3-406 oops with 4965AGN wireless

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Message-Id: <1270757373.11853.11.camel@wwguy-ubuntu>
Date:	Thu, 08 Apr 2010 13:09:33 -0700
From:	"Guy, Wey-Yi" <wey-yi.w.guy@...el.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Jeff Chua <jeff.chua.linux@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Zhao, Shanyu" <shanyu.zhao@...el.com>,
	"Chatre, Reinette" <reinette.chatre@...el.com>,
	"stable@...nel.org" <stable@...nel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [REVERT] be6b38bcb175613f239e0b302607db346472c6b6.
 v2.6.34-rc3-406 oops with 4965AGN wireless


On Thu, 2010-04-08 at 11:13 -0700, Al Viro wrote:
> On Fri, Apr 09, 2010 at 01:16:43AM +0800, Jeff Chua wrote:
> > 
> > index 1bd2cd8..83c52a6 100644
> > --- a/drivers/net/wireless/iwlwifi/iwl-4965.c
> > +++ b/drivers/net/wireless/iwlwifi/iwl-4965.c
> > @@ -2041,16 +2041,14 @@ static void iwl4965_rx_reply_tx(struct iwl_priv *priv,
> >  				   tx_resp->failure_frame);
> > 
> >  		freed = iwl_tx_queue_reclaim(priv, txq_id, index);
> > -		if (qc && likely(sta_id != IWL_INVALID_STATION))
> > -			priv->stations[sta_id].tid[tid].tfds_in_queue -= freed;
> > +		iwl_free_tfds_in_queue(priv, sta_id, tid, freed);
> 
> So what happens if we hit sta_id == IWL_INVALID_STATION and !txq->sched_retry?
> 
> AFAICS, IWL_INVALID_STATION is 255 and priv->stations[] has only 32 elements.
> And code around that place is
>         if (txq->sched_retry && unlikely(sta_id == IWL_INVALID_STATION)) {
>                 IWL_ERR(priv, "Station not known\n");
>                 return;
>         }
>         if (txq->sched_retry) {
> 		....
> 	} else {
> 		....
> 		the code modified in that chunk
> 		....
> 	}
> so this removal of check for sta_id doesn't look apriori safe...
> 
> I'm not familiar with that code and I don't have the hardware, so this is
> just from RTFS, but... might make sense to replace that call of
> iwl_free_tfds_in_queue with
> 
> 		if (sta_id == IWL_INVALID_STATION)
> 			printk(KERN_ERR "buggered");
> 		else
> 			iwl_free_tfds_in_queue(priv, sta_id, tid, freed);
> 
> and see if that helps and if printk gets triggered.

We can check for IWL_INVALID_STATION and print log, but need to check
for qc to make sure it is valid; maybe something like
			if (qc && likely(sta_id != IWL_INVALID_STATION))
				iwl_free_tfds_in_queue(priv, sta_id,
						       tid, freed);
			else {
				if (sta_id == IWL_INVALID_STATION)
					IWL_ERR(priv, "invalid station"");
			} 
	
Wey



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