From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets Date: Thu, 12 Apr 2012 18:08:00 +0200 Message-ID: <1334246880.5300.6736.camel@edumazet-glaptop> References: <1334221644-16056-1-git-send-email-will.deacon@arm.com> <1334222448.5300.6046.camel@edumazet-glaptop> <20120412125355.GG16025@mudshark.cambridge.arm.com> <1334235963.5300.6361.camel@edumazet-glaptop> <20120412134757.GH16025@mudshark.cambridge.arm.com> <1334239299.5300.6478.camel@edumazet-glaptop> <20120412155409.GA28204@mudshark.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , Steve Glendinning To: Will Deacon Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:63003 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932965Ab2DLQIF (ORCPT ); Thu, 12 Apr 2012 12:08:05 -0400 Received: by bkcik5 with SMTP id ik5so1654675bkc.19 for ; Thu, 12 Apr 2012 09:08:04 -0700 (PDT) In-Reply-To: <20120412155409.GA28204@mudshark.cambridge.arm.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2012-04-12 at 16:54 +0100, Will Deacon wrote: > Gotcha, so I can lose the pull too. Here's an updated patch with log, thanks > for the help. > > Will > > > Author: Will Deacon > Date: Thu Apr 12 13:54:17 2012 +0100 > > net: smsc911x: fix skb handling in receive path > > The SMSC911x driver resets the ->head, ->data and ->tail pointers in the > skb on the reset path in order to avoid buffer overflow due to packet > padding performed by the hardware. > > This patch fixes the receive path so that the skb pointers are fixed up > after the data has been read from the device, The error path is also > fixed to use number of words consistently and prevent erroneous FIFO > fastforwarding when skipping over bad data. > > Signed-off-by: Will Deacon > > diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c > index 4a69710..5aa2dbe 100644 > --- a/drivers/net/ethernet/smsc/smsc911x.c > +++ b/drivers/net/ethernet/smsc/smsc911x.c > @@ -1166,10 +1166,8 @@ smsc911x_rx_counterrors(struct net_device *dev, unsigned int rxstat) > > /* Quickly dumps bad packets */ > static void > -smsc911x_rx_fastforward(struct smsc911x_data *pdata, unsigned int pktbytes) > +smsc911x_rx_fastforward(struct smsc911x_data *pdata, unsigned int pktwords) > { > - unsigned int pktwords = (pktbytes + NET_IP_ALIGN + 3) >> 2; > - > if (likely(pktwords >= 4)) { > unsigned int timeout = 500; > unsigned int val; > @@ -1233,7 +1231,7 @@ static int smsc911x_poll(struct napi_struct *napi, int budget) > continue; > } > > - skb = netdev_alloc_skb(dev, pktlength + NET_IP_ALIGN); > + skb = netdev_alloc_skb(dev, pktwords << 2); > if (unlikely(!skb)) { > SMSC_WARN(pdata, rx_err, > "Unable to allocate skb for rx packet"); > @@ -1243,14 +1241,12 @@ static int smsc911x_poll(struct napi_struct *napi, int budget) > break; > } > > - skb->data = skb->head; > - skb_reset_tail_pointer(skb); > + pdata->ops->rx_readfifo(pdata, > + (unsigned int *)skb->data, pktwords); > > /* Align IP on 16B boundary */ > skb_reserve(skb, NET_IP_ALIGN); > skb_put(skb, pktlength - 4); > - pdata->ops->rx_readfifo(pdata, > - (unsigned int *)skb->head, pktwords); > skb->protocol = eth_type_trans(skb, dev); > skb_checksum_none_assert(skb); > netif_receive_skb(skb); > @@ -1565,7 +1561,7 @@ static int smsc911x_open(struct net_device *dev) > smsc911x_reg_write(pdata, FIFO_INT, temp); > > /* set RX Data offset to 2 bytes for alignment */ > - smsc911x_reg_write(pdata, RX_CFG, (2 << 8)); > + smsc911x_reg_write(pdata, RX_CFG, (NET_IP_ALIGN << 8)); > > /* enable NAPI polling before enabling RX interrupts */ > napi_enable(&pdata->napi); Seems fine to me Signed-off-by: Eric Dumazet