Re: 2.6.32-rc5-git3: Reported regressions from 2.6.31

[Michael Buesch <mb@bu3sch.de>]

On Wednesday 28 October 2009 21:38:37 Christian Casteyde wrote:
> I've just tested the patch posted in bugzilla: it works.
> That is, I do not manage to get the warning anymore in 3 boots in a row.

Thanks a lot for testing. I'll resend with proper signoff.

> CC
> Le mercredi 28 octobre 2009 20:05:47, John W. Linville a écrit :
> > Christian,
> > 
> > Will you be able to test this patch for us?
> > 
> > Thanks,
> > 
> > John
> > 
> > On Mon, Oct 26, 2009 at 09:38:28PM +0100, Michael Buesch wrote:
> > > On Monday 26 October 2009 20:37:33 Michael Buesch wrote:
> > > > Ok, it just turns out this actually is a driver bug.
> > > > Thanks to Johannes Berg for tracking it down.
> > > >
> > > > I think it's caused by the DMA bouncebuffer stuff that does not copy
> > > > the skb->cb and does not adjust the "tx-info" pointer.
> > > > I wonder why this didn't blow up easlier, because this bug is there
> > > > since mac80211 switched to using the CB.
> > > >
> > > > Here's a completely untested patch.
> > >
> > > Here's a new version of the patch that also fixes queue mapping bugs:
> > >
> > > ---
> > >  drivers/net/wireless/b43/dma.c |   15 +++++++++++++--
> > >  1 file changed, 13 insertions(+), 2 deletions(-)
> > >
> > > --- wireless-testing.orig/drivers/net/wireless/b43/dma.c
> > > +++ wireless-testing/drivers/net/wireless/b43/dma.c
> > > @@ -1157,8 +1157,9 @@ struct b43_dmaring *parse_cookie(struct
> > >  }
> > >
> > >  static int dma_tx_fragment(struct b43_dmaring *ring,
> > > -			   struct sk_buff *skb)
> > > +			   struct sk_buff **in_skb)
> > >  {
> > > +	struct sk_buff *skb = *in_skb;
> > >  	const struct b43_dma_ops *ops = ring->ops;
> > >  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
> > >  	u8 *header;
> > > @@ -1224,8 +1225,14 @@ static int dma_tx_fragment(struct b43_dm
> > >  		}
> > >
> > >  		memcpy(skb_put(bounce_skb, skb->len), skb->data, skb->len);
> > > +		memcpy(bounce_skb->cb, skb->cb, sizeof(skb->cb));
> > > +		bounce_skb->dev = skb->dev;
> > > +		skb_set_queue_mapping(bounce_skb, skb_get_queue_mapping(skb));
> > > +		info = IEEE80211_SKB_CB(bounce_skb);
> > > +
> > >  		dev_kfree_skb_any(skb);
> > >  		skb = bounce_skb;
> > > +		*in_skb = bounce_skb;
> > >  		meta->skb = skb;
> > >  		meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
> > >  		if (b43_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
> > > @@ -1355,7 +1362,11 @@ int b43_dma_tx(struct b43_wldev *dev, st
> > >  	 * static, so we don't need to store it per frame. */
> > >  	ring->queue_prio = skb_get_queue_mapping(skb);
> > >
> > > -	err = dma_tx_fragment(ring, skb);
> > > +	/* dma_tx_fragment might reallocate the skb, so invalidate pointers
> > > pointing +	 * into the skb data or cb now. */
> > > +	hdr = NULL;
> > > +	info = NULL;
> > > +	err = dma_tx_fragment(ring, &skb);
> > >  	if (unlikely(err == -ENOKEY)) {
> > >  		/* Drop this packet, as we don't have the encryption key
> > >  		 * anymore and must not transmit it unencrypted. */
> > 
> 
> 



-- 
Greetings, Michael.