[PATCH] net: macb: Disable macb pad and fcs for fragmented packets

[PATCH] net: macb: Disable macb pad and fcs for fragmented packets

[Harini Katakam]

data_len in skbuff represents bytes resident in fragment lists or
unmapped page buffers. For such packets, when data_len is non-zero,
skb_put cannot be used - this will throw a kernel bug. Hence do not
use macb_pad_and_fcs for such fragments.

Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 6434e74c04f1..0b03305ad6a0 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1995,7 +1995,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
 			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
 			if ((bp->dev->features & NETIF_F_HW_CSUM) &&
-			    skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl)
+			    skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl &&
+			    (skb->data_len == 0))
 				ctrl |= MACB_BIT(TX_NOCRC);
 		} else
 			/* Only set MSS/MFS on payload descriptors
@@ -2091,9 +2092,11 @@ static int macb_pad_and_fcs(struct sk_buff **skb, struct net_device *ndev)
 	struct sk_buff *nskb;
 	u32 fcs;
 
+	/* Not available for GSO and fragments */
 	if (!(ndev->features & NETIF_F_HW_CSUM) ||
 	    !((*skb)->ip_summed != CHECKSUM_PARTIAL) ||
-	    skb_shinfo(*skb)->gso_size)	/* Not available for GSO */
+	    skb_shinfo(*skb)->gso_size ||
+	    ((*skb)->data_len > 0))
 		return 0;
 
 	if (padlen <= 0) {
-- 
2.17.1

Re: [PATCH] net: macb: Disable macb pad and fcs for fragmented packets

[Claudiu.Beznea]

On 09.05.2022 15:15, Harini Katakam wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> data_len in skbuff represents bytes resident in fragment lists or
> unmapped page buffers. For such packets, when data_len is non-zero,
> skb_put cannot be used - this will throw a kernel bug. Hence do not
> use macb_pad_and_fcs for such fragments.
> 
> Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>

Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>


> ---
>  drivers/net/ethernet/cadence/macb_main.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 6434e74c04f1..0b03305ad6a0 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -1995,7 +1995,8 @@ static unsigned int macb_tx_map(struct macb *bp,
>                         ctrl |= MACB_BF(TX_LSO, lso_ctrl);
>                         ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
>                         if ((bp->dev->features & NETIF_F_HW_CSUM) &&
> -                           skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl)
> +                           skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl &&
> +                           (skb->data_len == 0))
>                                 ctrl |= MACB_BIT(TX_NOCRC);
>                 } else
>                         /* Only set MSS/MFS on payload descriptors
> @@ -2091,9 +2092,11 @@ static int macb_pad_and_fcs(struct sk_buff **skb, struct net_device *ndev)
>         struct sk_buff *nskb;
>         u32 fcs;
> 
> +       /* Not available for GSO and fragments */
>         if (!(ndev->features & NETIF_F_HW_CSUM) ||
>             !((*skb)->ip_summed != CHECKSUM_PARTIAL) ||
> -           skb_shinfo(*skb)->gso_size) /* Not available for GSO */
> +           skb_shinfo(*skb)->gso_size ||
> +           ((*skb)->data_len > 0))
>                 return 0;
> 
>         if (padlen <= 0) {
> --
> 2.17.1
> 

Re: [PATCH] net: macb: Disable macb pad and fcs for fragmented packets

[Paolo Abeni]

On Mon, 2022-05-09 at 17:45 +0530, Harini Katakam wrote:
> data_len in skbuff represents bytes resident in fragment lists or
> unmapped page buffers. For such packets, when data_len is non-zero,
> skb_put cannot be used - this will throw a kernel bug. Hence do not
> use macb_pad_and_fcs for such fragments.
> 
> Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>

This looks like a fix suitable for the net tree. Please add a relevant
'Fixes' tag.

> ---
>  drivers/net/ethernet/cadence/macb_main.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 6434e74c04f1..0b03305ad6a0 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -1995,7 +1995,8 @@ static unsigned int macb_tx_map(struct macb *bp,
>  			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
>  			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
>  			if ((bp->dev->features & NETIF_F_HW_CSUM) &&
> -			    skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl)
> +			    skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl &&
> +			    (skb->data_len == 0))
>  				ctrl |= MACB_BIT(TX_NOCRC);
>  		} else
>  			/* Only set MSS/MFS on payload descriptors

This chunk looks unrelated to the commit message ?!? only the next one
looks relevant.

Thanks.

Paolo

Re: [PATCH] net: macb: Disable macb pad and fcs for fragmented packets

[Harini Katakam]

Hi Paolo,

On Tue, May 10, 2022 at 6:48 PM Paolo Abeni <pabeni@redhat.com> wrote:
>
> On Mon, 2022-05-09 at 17:45 +0530, Harini Katakam wrote:
> > data_len in skbuff represents bytes resident in fragment lists or
> > unmapped page buffers. For such packets, when data_len is non-zero,
> > skb_put cannot be used - this will throw a kernel bug. Hence do not
> > use macb_pad_and_fcs for such fragments.
> >
> > Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
> > Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> > Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
>
> This looks like a fix suitable for the net tree. Please add a relevant
> 'Fixes' tag.
>
> > ---
> >  drivers/net/ethernet/cadence/macb_main.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> > index 6434e74c04f1..0b03305ad6a0 100644
> > --- a/drivers/net/ethernet/cadence/macb_main.c
> > +++ b/drivers/net/ethernet/cadence/macb_main.c
> > @@ -1995,7 +1995,8 @@ static unsigned int macb_tx_map(struct macb *bp,
> >                       ctrl |= MACB_BF(TX_LSO, lso_ctrl);
> >                       ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
> >                       if ((bp->dev->features & NETIF_F_HW_CSUM) &&
> > -                         skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl)
> > +                         skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl &&
> > +                         (skb->data_len == 0))
> >                               ctrl |= MACB_BIT(TX_NOCRC);
> >               } else
> >                       /* Only set MSS/MFS on payload descriptors
>
> This chunk looks unrelated to the commit message ?!? only the next one
> looks relevant.

Thanks for the review. This code is related to the commit message.
macb_pad_and_fcs is performed on the same packets on which
TX_NOCRC is set (instruct HW not to perform CRC and perform
CRC in SW). This is the patch which added both:
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/drivers/net/ethernet/cadence?id=653e92a9175ea7ed67efe209c725222051a3713d
I'll mention the same in Fixes tag and also add Claudiu's review tag.

Regards,
Harini