Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754093AbaJGO1S (ORCPT ); Tue, 7 Oct 2014 10:27:18 -0400 Received: from mail-pd0-f181.google.com ([209.85.192.181]:50870 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752480AbaJGO1Q (ORCPT ); Tue, 7 Oct 2014 10:27:16 -0400 Message-ID: <1412692034.11091.122.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: [PATCH] net: fec: fix regression on i.MX28 introduced by rx_copybreak support From: Eric Dumazet To: Lothar =?ISO-8859-1?Q?Wa=DFmann?= Cc: netdev@vger.kernel.org, "David S. Miller" , Russell King , Frank Li , Fabio Estevam , linux-kernel@vger.kernel.org Date: Tue, 07 Oct 2014 07:27:14 -0700 In-Reply-To: <1412687977-11742-1-git-send-email-LW@KARO-electronics.de> References: <1412687977-11742-1-git-send-email-LW@KARO-electronics.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-10-07 at 15:19 +0200, Lothar Waßmann wrote: > 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. > > Signed-off-by: Lothar Waßmann > --- > drivers/net/ethernet/freescale/fec_main.c | 25 +++++++++++++++++++++---- > 1 file changed, 21 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c > index 87975b5..eaaebad 100644 > --- a/drivers/net/ethernet/freescale/fec_main.c > +++ b/drivers/net/ethernet/freescale/fec_main.c > @@ -339,6 +339,18 @@ static void *swap_buffer(void *bufaddr, int len) > return bufaddr; > } > > +static void *swap_buffer2(void *dst_buf, void *src_buf, int len) > +{ > + int i; > + unsigned int *src = src_buf; > + unsigned int *dst = dst_buf; > + > + for (i = 0; i < DIV_ROUND_UP(len, 4); i++, src++, dst++) > + *dst = cpu_to_be32(*src); No need for the DIV : for (i = 0; i < len; i += sizeof(*dst), src++, dst++) *dst = cpu_to_be32(*src); Also are you sure both src/dst are aligned to word boundaries, or is this architecture OK with possible misalignment ? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/