[PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Will Deacon]

The SMSC911x ethernet controller provides a mechanism for quickly
skipping to the start of the next frame in the receive FIFO, however
the current code passes the number of words to a function that expects
the number of bytes. This can corrupt the FIFO head in the case that
the fastforward mechanism is not used.

This patch fixes the callers of smsc911x_rx_fastforward to pass the
correct data size.

Cc: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 drivers/net/ethernet/smsc/smsc911x.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
index 4a69710..b5599bc 100644
--- a/drivers/net/ethernet/smsc/smsc911x.c
+++ b/drivers/net/ethernet/smsc/smsc911x.c
@@ -1228,7 +1228,7 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
 				  "Discarding packet with error bit set");
 			/* Packet has an error, discard it and continue with
 			 * the next */
-			smsc911x_rx_fastforward(pdata, pktwords);
+			smsc911x_rx_fastforward(pdata, pktlength);
 			dev->stats.rx_dropped++;
 			continue;
 		}
@@ -1238,7 +1238,7 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
 			SMSC_WARN(pdata, rx_err,
 				  "Unable to allocate skb for rx packet");
 			/* Drop the packet and stop this polling iteration */
-			smsc911x_rx_fastforward(pdata, pktwords);
+			smsc911x_rx_fastforward(pdata, pktlength);
 			dev->stats.rx_dropped++;
 			break;
 		}
-- 
1.7.4.1

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Eric Dumazet]

On Thu, 2012-04-12 at 10:07 +0100, Will Deacon wrote:
> The SMSC911x ethernet controller provides a mechanism for quickly
> skipping to the start of the next frame in the receive FIFO, however
> the current code passes the number of words to a function that expects
> the number of bytes. This can corrupt the FIFO head in the case that
> the fastforward mechanism is not used.
> 
> This patch fixes the callers of smsc911x_rx_fastforward to pass the
> correct data size.
> 
> Cc: Steve Glendinning <steve.glendinning@smsc.com>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> ---
>  drivers/net/ethernet/smsc/smsc911x.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
> index 4a69710..b5599bc 100644
> --- a/drivers/net/ethernet/smsc/smsc911x.c
> +++ b/drivers/net/ethernet/smsc/smsc911x.c
> @@ -1228,7 +1228,7 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
>  				  "Discarding packet with error bit set");
>  			/* Packet has an error, discard it and continue with
>  			 * the next */
> -			smsc911x_rx_fastforward(pdata, pktwords);
> +			smsc911x_rx_fastforward(pdata, pktlength);
>  			dev->stats.rx_dropped++;
>  			continue;
>  		}
> @@ -1238,7 +1238,7 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
>  			SMSC_WARN(pdata, rx_err,
>  				  "Unable to allocate skb for rx packet");
>  			/* Drop the packet and stop this polling iteration */
> -			smsc911x_rx_fastforward(pdata, pktwords);
> +			smsc911x_rx_fastforward(pdata, pktlength);
>  			dev->stats.rx_dropped++;
>  			break;
>  		}

Hum, looking at this driver, I see wrong code in lines 1246/1247

skb->data = skb->head;
skb_reset_tail_pointer(skb);

I suspect its hiding a buffer overflow bug or something.

netdev_alloc_skb() reserved NET_SKB_PAD bytes. A driver should not
un-reserve this headroom, or some networking setups can be very slow.

So 

pdata->ops->rx_readfifo(pdata,
	(unsigned int *)skb->head, pktwords);

also should be fixed to use skb->data instead.

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Will Deacon]

Hi Eric,

Thanks for taking a look.

On Thu, Apr 12, 2012 at 10:20:48AM +0100, Eric Dumazet wrote:
> On Thu, 2012-04-12 at 10:07 +0100, Will Deacon wrote:
> > diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
> > index 4a69710..b5599bc 100644
> > --- a/drivers/net/ethernet/smsc/smsc911x.c
> > +++ b/drivers/net/ethernet/smsc/smsc911x.c
> > @@ -1228,7 +1228,7 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
> >  				  "Discarding packet with error bit set");
> >  			/* Packet has an error, discard it and continue with
> >  			 * the next */
> > -			smsc911x_rx_fastforward(pdata, pktwords);
> > +			smsc911x_rx_fastforward(pdata, pktlength);
> >  			dev->stats.rx_dropped++;
> >  			continue;
> >  		}

[...]

> Hum, looking at this driver, I see wrong code in lines 1246/1247
> 
> skb->data = skb->head;
> skb_reset_tail_pointer(skb);
> 
> I suspect its hiding a buffer overflow bug or something.

Yes, you're right.

> netdev_alloc_skb() reserved NET_SKB_PAD bytes. A driver should not
> un-reserve this headroom, or some networking setups can be very slow.
> 
> So 
> 
> pdata->ops->rx_readfifo(pdata,
> 	(unsigned int *)skb->head, pktwords);
> 
> also should be fixed to use skb->data instead.

Right, this seems to do the trick (and can replace my original patch by
actually passing in the number of words to the fastforward function). I'm
not sure whether the skb_trim is really required, but it makes the data
format slightly clearer.

It would be nice to get some input from Steve, but his email address seems
to be bouncing at the moment.

Will


diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
index 4a69710..3f43c24 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");
@@ -1243,21 +1241,19 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
                        break;
                }
 
-               skb->data = skb->head;
-               skb_reset_tail_pointer(skb);
-
-               /* Align IP on 16B boundary */
-               skb_reserve(skb, NET_IP_ALIGN);
-               skb_put(skb, pktlength - 4);
+               skb_put(skb, pktwords << 2);
                pdata->ops->rx_readfifo(pdata,
-                                (unsigned int *)skb->head, pktwords);
+                                (unsigned int *)skb->data, pktwords);
+               skb_pull(skb, NET_IP_ALIGN);
+               skb_trim(skb, pktlength);
+
                skb->protocol = eth_type_trans(skb, dev);
                skb_checksum_none_assert(skb);
                netif_receive_skb(skb);
 
                /* Update counters */
                dev->stats.rx_packets++;
-               dev->stats.rx_bytes += (pktlength - 4);
+               dev->stats.rx_bytes += pktlength;
        }
 
        /* Return total received packets */
@@ -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);

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Eric Dumazet]

On Thu, 2012-04-12 at 13:53 +0100, Will Deacon wrote:
> Hi Eric,
> 
> Thanks for taking a look.
> 
> On Thu, Apr 12, 2012 at 10:20:48AM +0100, Eric Dumazet wrote:
> > On Thu, 2012-04-12 at 10:07 +0100, Will Deacon wrote:
> > > diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
> > > index 4a69710..b5599bc 100644
> > > --- a/drivers/net/ethernet/smsc/smsc911x.c
> > > +++ b/drivers/net/ethernet/smsc/smsc911x.c
> > > @@ -1228,7 +1228,7 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
> > >  				  "Discarding packet with error bit set");
> > >  			/* Packet has an error, discard it and continue with
> > >  			 * the next */
> > > -			smsc911x_rx_fastforward(pdata, pktwords);
> > > +			smsc911x_rx_fastforward(pdata, pktlength);
> > >  			dev->stats.rx_dropped++;
> > >  			continue;
> > >  		}
> 
> [...]
> 
> > Hum, looking at this driver, I see wrong code in lines 1246/1247
> > 
> > skb->data = skb->head;
> > skb_reset_tail_pointer(skb);
> > 
> > I suspect its hiding a buffer overflow bug or something.
> 
> Yes, you're right.
> 
> > netdev_alloc_skb() reserved NET_SKB_PAD bytes. A driver should not
> > un-reserve this headroom, or some networking setups can be very slow.
> > 
> > So 
> > 
> > pdata->ops->rx_readfifo(pdata,
> > 	(unsigned int *)skb->head, pktwords);
> > 
> > also should be fixed to use skb->data instead.
> 
> Right, this seems to do the trick (and can replace my original patch by
> actually passing in the number of words to the fastforward function). I'm
> not sure whether the skb_trim is really required, but it makes the data
> format slightly clearer.
> 
> It would be nice to get some input from Steve, but his email address seems
> to be bouncing at the moment.
> 
> Will
> 
> 
> diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
> index 4a69710..3f43c24 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");
> @@ -1243,21 +1241,19 @@ static int smsc911x_poll(struct napi_struct *napi, int budget)
>                         break;
>                 }
>  
> -               skb->data = skb->head;
> -               skb_reset_tail_pointer(skb);
> -
> -               /* Align IP on 16B boundary */
> -               skb_reserve(skb, NET_IP_ALIGN);
> -               skb_put(skb, pktlength - 4);
> +               skb_put(skb, pktwords << 2);

You could remove this line and do it after skb_reserve() ?

>                 pdata->ops->rx_readfifo(pdata,
> -                                (unsigned int *)skb->head, pktwords);
> +                                (unsigned int *)skb->data, pktwords);
> +               skb_pull(skb, NET_IP_ALIGN);

		skb_reserve(skb, NET_IP_ALIGN);
		skb_put(skb, pktlength - 4);

> +               skb_trim(skb, pktlength);

and remove this skb_trim()

> +
>                 skb->protocol = eth_type_trans(skb, dev);
>                 skb_checksum_none_assert(skb);
>                 netif_receive_skb(skb);
>  
>                 /* Update counters */
>                 dev->stats.rx_packets++;
> -               dev->stats.rx_bytes += (pktlength - 4);
> +               dev->stats.rx_bytes += pktlength;
	
	Some drivers account for the FCS, some dont, I guess you can leave the
line as is

>         }
>  
>         /* Return total received packets */
> @@ -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));

	Good ;)

>  
>         /* enable NAPI polling before enabling RX interrupts */
>         napi_enable(&pdata->napi);
> 

Thanks

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Will Deacon]

On Thu, Apr 12, 2012 at 02:06:03PM +0100, Eric Dumazet wrote:
> On Thu, 2012-04-12 at 13:53 +0100, Will Deacon wrote:
> > diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
> > index 4a69710..3f43c24 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)

[...]

> > -               skb->data = skb->head;
> > -               skb_reset_tail_pointer(skb);
> > -
> > -               /* Align IP on 16B boundary */
> > -               skb_reserve(skb, NET_IP_ALIGN);
> > -               skb_put(skb, pktlength - 4);
> > +               skb_put(skb, pktwords << 2);
> 
> You could remove this line and do it after skb_reserve() ?
> 
> >                 pdata->ops->rx_readfifo(pdata,
> > -                                (unsigned int *)skb->head, pktwords);
> > +                                (unsigned int *)skb->data, pktwords);
> > +               skb_pull(skb, NET_IP_ALIGN);
> 
> 		skb_reserve(skb, NET_IP_ALIGN);

I don't think we want an skb_reserve at all, since the hardware shifts the
data in the RX FIFO, meaning that we will read two bytes of 0 anyway before
valid data.

> 		skb_put(skb, pktlength - 4);

I can move the put here if you like, but we need to use pktwords << 2 to
make sure that we read the leading and trailing zeroes inserted by the
hardware.

> > +               skb_trim(skb, pktlength);
> 
> and remove this skb_trim()

Can do, just thought it might help illustrate that we might have some padding
at the end.

> >                 /* Update counters */
> >                 dev->stats.rx_packets++;
> > -               dev->stats.rx_bytes += (pktlength - 4);
> > +               dev->stats.rx_bytes += pktlength;
> 	
> 	Some drivers account for the FCS, some dont, I guess you can leave the
> line as is

Sure.

Thanks for the comments,

Will

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Eric Dumazet]

On Thu, 2012-04-12 at 14:47 +0100, Will Deacon wrote:

> 
> I don't think we want an skb_reserve at all, since the hardware shifts the
> data in the RX FIFO, meaning that we will read two bytes of 0 anyway before
> valid data.
> 
> > 		skb_put(skb, pktlength - 4);
> 
> I can move the put here if you like, but we need to use pktwords << 2 to
> make sure that we read the leading and trailing zeroes inserted by the
> hardware.

before calling linux stack, you'll have to skip those 2 bytes.

This is skb_reserve() purpose.

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Will Deacon]

On Thu, Apr 12, 2012 at 03:01:39PM +0100, Eric Dumazet wrote:
> On Thu, 2012-04-12 at 14:47 +0100, Will Deacon wrote:
> 
> > 
> > I don't think we want an skb_reserve at all, since the hardware shifts the
> > data in the RX FIFO, meaning that we will read two bytes of 0 anyway before
> > valid data.
> > 
> > > 		skb_put(skb, pktlength - 4);
> > 
> > I can move the put here if you like, but we need to use pktwords << 2 to
> > make sure that we read the leading and trailing zeroes inserted by the
> > hardware.
> 
> before calling linux stack, you'll have to skip those 2 bytes.
> 
> This is skb_reserve() purpose.

Gotcha, so I can lose the pull too. Here's an updated patch with log, thanks
for the help.

Will


Author: Will Deacon <will.deacon@arm.com>
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 <will.deacon@arm.com>

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);

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Eric Dumazet]

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 <will.deacon@arm.com>
> 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 <will.deacon@arm.com>
> 
> 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 <eric.dumazet@gmail.com>

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Will Deacon]

On Thu, Apr 12, 2012 at 05:08:00PM +0100, Eric Dumazet wrote:
> On Thu, 2012-04-12 at 16:54 +0100, Will Deacon wrote:
> >     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 <will.deacon@arm.com>

[...]

> Seems fine to me
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Thanks, Eric. Given that Steve's email doesn't appear to be working, can
somebody else pick this up please?

Cheers,

Will

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[Eric Dumazet]

On Thu, 2012-04-12 at 18:03 +0100, Will Deacon wrote:


> > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> 
> Thanks, Eric. Given that Steve's email doesn't appear to be working, can
> somebody else pick this up please?

It seems trivial enough, you tested it, and I reviewed it.

I believe David can apply it safely.

Thanks

Re: [PATCH] net: smsc911x: fix RX FIFO fastforwarding when dropping packets

[David Miller]

From: Will Deacon <will.deacon@arm.com>
Date: Thu, 12 Apr 2012 18:03:50 +0100

> On Thu, Apr 12, 2012 at 05:08:00PM +0100, Eric Dumazet wrote:
>> On Thu, 2012-04-12 at 16:54 +0100, Will Deacon wrote:
>> >     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 <will.deacon@arm.com>
> 
> [...]
> 
>> Seems fine to me
>> 
>> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> 
> Thanks, Eric. Given that Steve's email doesn't appear to be working, can
> somebody else pick this up please?

Applied, thanks.