From: Dave Jones <davej@redhat.com>
To: David Miller <davem@davemloft.net>
Cc: simon.kagstrom@netinsight.net, netdev@vger.kernel.org
Subject: Re: via-velocity dma-debug warnings again. (2.6.35.2)
Date: Wed, 1 Sep 2010 16:05:55 -0400 [thread overview]
Message-ID: <20100901200555.GA30689@redhat.com> (raw)
In-Reply-To: <20100901.130333.148556201.davem@davemloft.net>
On Wed, Sep 01, 2010 at 01:03:33PM -0700, David Miller wrote:
> From: Simon Kagstrom <simon.kagstrom@netinsight.net>
> Date: Wed, 1 Sep 2010 12:20:59 +0200
>
> > I'm not really an expert on the subject, but with skb_headlen(), the size
> > should be the same for pci_map_single and pci_unmap_single as far as I
> > can tell.
>
> That's not the case.
>
> You'll have to use exactly the same formula for computing the length
> as the pci_map_single() call uses, which is:
>
> pktlen = skb_shinfo(skb)->nr_frags == 0 ?
> max_t(unsigned int, skb->len, ETH_ZLEN) :
> skb_headlen(skb);
>
> Otherwise packets smaller than ETH_ZLEN will be unmapped properly
> and trigger the same kind of debugging checks Dave is seeing.
Looks like you're right.
[ 5674.506024] via-velocity 0000:00:0e.0: DMA-API: device driver frees DMA memory with different size [device address=0x0000000018e555fa] [map size=54 bytes] [unmap size=108 bytes]
Dave
next prev parent reply other threads:[~2010-09-01 20:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-31 1:13 via-velocity dma-debug warnings again. (2.6.35.2) Dave Jones
2010-08-31 1:19 ` Dave Jones
2010-08-31 9:10 ` Simon Kagstrom
2010-08-31 17:21 ` Dave Jones
2010-09-01 10:20 ` Simon Kagstrom
2010-09-01 20:03 ` David Miller
2010-09-01 20:05 ` Dave Jones [this message]
2010-09-01 20:34 ` David Miller
2010-09-01 20:35 ` David Miller
2010-09-01 20:37 ` David Miller
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