From: "Lothar Waßmann" <LW@KARO-electronics•de>
To: David Laight <David.Laight@ACULAB•COM>
Cc: "netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"David S. Miller" <davem@davemloft•net>,
Russell King <rmk+kernel@arm•linux.org.uk>,
Frank Li <Frank.Li@freescale•com>,
"Fabio Estevam" <fabio.estevam@freescale•com>,
"linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>
Subject: Re: [PATCH] net: fec: fix regression on i.MX28 introduced by rx_copybreak support
Date: Tue, 7 Oct 2014 16:17:02 +0200 [thread overview]
Message-ID: <20141007161702.7cd1e800@ipc1.ka-ro> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D174C6025@AcuExch.aculab.com>
Hi,
David Laight wrote:
> From: Lothar Waßmann
> > commit 1b7bde6d659d ("net: fec: implement rx_copybreak to improve rx performance")
> > introduced a regression for i.MX28. The swap_buffer() function doing
> > the endian conversion of the received data on i.MX28 may access memory
> > beyond the actual packet size in the DMA buffer. fec_enet_copybreak()
> > does not copy those bytes, so that the last bytes of a packet may be
> > filled with invalid data after swapping.
> > This will likely lead to checksum errors on received packets.
> > E.g. when trying to mount an NFS rootfs:
> > UDP: bad checksum. From 192.168.1.225:111 to 192.168.100.73:44662 ulen 36
> >
> > Do the byte swapping and copying to the new skb in one go if
> > necessary.
>
> ISTM that if you need to do the 'swap' you should copy the data regardless
> of the length.
>
The swap function has to look at at most 3 bytes beyond the actual
packet length. That is what the original swap_buffer() function does and
what the new function swap_buffer2(), that does the endian swapping
while copying to the new buffer, also does.
Lothar Waßmann
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next prev parent reply other threads:[~2014-10-07 14:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-07 13:19 [PATCH] net: fec: fix regression on i.MX28 introduced by rx_copybreak support Lothar Waßmann
2014-10-07 13:31 ` David Laight
2014-10-07 14:17 ` Lothar Waßmann [this message]
2014-10-07 14:23 ` David Laight
2014-10-07 14:34 ` Eric Dumazet
2014-10-08 4:59 ` Lothar Waßmann
2014-10-07 14:02 ` Fabio Estevam
2014-10-07 14:27 ` Eric Dumazet
2014-10-07 14:41 ` David Laight
2014-10-08 5:01 ` Lothar Waßmann
2014-10-08 8:45 ` David Laight
2014-10-08 8:55 ` Lothar Waßmann
2014-10-07 16:07 ` Sergei Shtylyov
2014-10-08 8:54 ` David Laight
2014-10-08 9:12 ` Russell King - ARM Linux
2014-10-07 17:15 ` David Miller
2014-10-08 4:43 ` Lothar Waßmann
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