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Re: [PATCH v3.7] brcmsmac: handle packet drop on enqueuing correctly

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On Mon, Nov 26, 2012 at 08:55:11AM -0600, Seth Forshee wrote:
> On Fri, Nov 23, 2012 at 12:44:42PM +0100, Arend van Spriel wrote:
> > From: Piotr Haber <phaber@xxxxxxxxxxxx>
> > 
> > In the event that tx packet can not be queued by the driver
> > the packet is dropped. Propagate that information to the .tx()
> > callback to make sure the freed packet is not accessed after
> > that.
> > 
> > This has happened causing slab corruptions as reported by
> > Stanislaw Gruszka.
> > 
> > Bug #47721: https://bugzilla.kernel.org/show_bug.cgi?id=47721
> > 
> > Reported-by: Stanislaw Gruszka <stf_xl@xxxxx>
> > Reviewed-by: Arend van Spriel <arend@xxxxxxxxxxxx>
> > Reviewed-by: Pieter-Paul Giesberts <pieterpg@xxxxxxxxxxxx>
> > Signed-off-by: Piotr Haber <phaber@xxxxxxxxxxxx>
> > Signed-off-by: Arend van Spriel <arend@xxxxxxxxxxxx>
> > ---
> > Fixing a kernel bug so based on the wireless repository. The
> > fix for wireless-next will be posted separately as the patches
> > differ. So this patch does not need to be merged to the
> > wireless-next tree.
> 
> Let me know if I can be of help in resolving the conflicts. Fwiw the fix
> looks like it ought to be easy to make on top of wireless-next, but I do
> have a couple of comments.
> 
> > diff --git a/drivers/net/wireless/brcm80211/brcmsmac/ampdu.c b/drivers/net/wireless/brcm80211/brcmsmac/ampdu.c
> > index be5bcfb..a6605b1 100644
> > --- a/drivers/net/wireless/brcm80211/brcmsmac/ampdu.c
> > +++ b/drivers/net/wireless/brcm80211/brcmsmac/ampdu.c
> > @@ -901,7 +901,7 @@ brcms_c_ampdu_dotxstatus_complete(struct ampdu_info *ampdu, struct scb *scb,
> >  	struct ieee80211_hdr *h;
> >  	u16 seq, start_seq = 0, bindex, index, mcl;
> >  	u8 mcs = 0;
> > -	bool ba_recd = false, ack_recd = false;
> > +	bool ba_recd = false, ack_recd = false, last_packet = false;
> >  	u8 suc_mpdu = 0, tot_mpdu = 0;
> >  	uint supr_status;
> >  	bool update_rate = true, retry = true, tx_error = false;
> > @@ -1010,6 +1010,8 @@ brcms_c_ampdu_dotxstatus_complete(struct ampdu_info *ampdu, struct scb *scb,
> >  
> >  		index = TX_SEQ_TO_INDEX(seq);
> >  		ack_recd = false;
> > +		last_packet = (((mcl & TXC_AMPDU_MASK) >> TXC_AMPDU_SHIFT) ==
> > +			TXC_AMPDU_LAST);
> >  		if (ba_recd) {
> >  			bindex = MODSUB_POW2(seq, start_seq, SEQNUM_MAX);
> >  			BCMMSG(wiphy,
> > @@ -1074,8 +1076,7 @@ brcms_c_ampdu_dotxstatus_complete(struct ampdu_info *ampdu, struct scb *scb,
> >  		tot_mpdu++;
> >  
> >  		/* break out if last packet of ampdu */
> > -		if (((mcl & TXC_AMPDU_MASK) >> TXC_AMPDU_SHIFT) ==
> > -		    TXC_AMPDU_LAST)
> > +		if (last_packet)
> >  			break;
> >  
> >  		p = dma_getnexttxp(wlc->hw->di[queue], DMA_RANGE_TRANSMITTED);
> 
> These changes are effectively a no-op and don't really seem to have
> anything to do with fixing the bug.

I concur -- could you remove these bits for the 3.7 fix?

> 
> > @@ -7288,10 +7290,12 @@ void brcms_c_sendpkt_mac80211(struct brcms_c_info *wlc, struct sk_buff *sdu,
> >  	prio = ieee80211_is_data(d11_header->frame_control) ? sdu->priority :
> >  		MAXPRIO;
> >  	fifo = prio2fifo[prio];
> > -	if (brcms_c_d11hdrs_mac80211(wlc, hw, sdu, scb, 0, 1, fifo, 0))
> > -		return;
> > -	brcms_c_txq_enq(wlc, scb, sdu, BRCMS_PRIO_TO_PREC(prio));
> > +	brcms_c_d11hdrs_mac80211(wlc, hw, sdu, scb, 0, 1, fifo, 0);
> 
> Maybe brcms_c_d11hdrs_mac80211() should return void? I've never
> understood what its return value was supposed to represent.
> 
> Cheers,
> Seth
> 
> 

-- 
John W. Linville		Someday the world will need a hero, and you
linville@xxxxxxxxxxxxx			might be all we have.  Be ready.
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