[PATCH net v5] net: xilinx: axienet: Fix IRQ coalescing packet count overflow

[Pandey, Radhey Shyam]

> -----Original Message-----
> From: Sean Anderson <sean.anderson at linux.dev>
> Sent: Monday, January 13, 2025 10:00 PM
> To: Pandey, Radhey Shyam <radhey.shyam.pandey at amd.com>; Nelson, Shannon
> <Shannon.Nelson at amd.com>; David S . Miller <davem at davemloft.net>; Eric
> Dumazet <edumazet at google.com>; Jakub Kicinski <kuba at kernel.org>; Paolo
> Abeni <pabeni at redhat.com>; netdev at vger.kernel.org
> Cc: linux-arm-kernel at lists.infradead.org; Simon Horman <horms at kernel.org>;
> Simek, Michal <michal.simek at amd.com>; linux-kernel at vger.kernel.org; Daniel
> Borkmann <daniel at iogearbox.net>; Sean Anderson <sean.anderson at linux.dev>
> Subject: [PATCH net v5] net: xilinx: axienet: Fix IRQ coalescing packet count
> overflow
> 
> If coalesce_count is greater than 255 it will not fit in the register and
> will overflow. This can be reproduced by running
> 
>     # ethtool -C ethX rx-frames 256
> 
> which will result in a timeout of 0us instead. Fix this by checking for
> invalid values and reporting an error.
> 
> Fixes: 8a3b7a252dca ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
> Signed-off-by: Sean Anderson <sean.anderson at linux.dev>
> Reviewed-by: Shannon Nelson <shannon.nelson at amd.com>

Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey at amd.com>
Thanks!
> ---
> 
> Changes in v5:
> - Fix typo in commit message
> 
> Changes in v4:
> - Fix checking rx twice instead of rx and tx
> 
> Changes in v3:
> - Validate and reject instead of silently clamping
> 
> Changes in v2:
> - Use FIELD_MAX to extract the max value from the mask
> - Expand the commit message with an example on how to reproduce this
>   issue
> 
>  drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> index 0f4b02fe6f85..ae743991117c 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
> @@ -2056,6 +2056,12 @@ axienet_ethtools_set_coalesce(struct net_device *ndev,
>  		return -EBUSY;
>  	}
> 
> +	if (ecoalesce->rx_max_coalesced_frames > 255 ||
> +	    ecoalesce->tx_max_coalesced_frames > 255) {
> +		NL_SET_ERR_MSG(extack, "frames must be less than 256");
> +		return -EINVAL;
> +	}
> +
>  	if (ecoalesce->rx_max_coalesced_frames)
>  		lp->coalesce_count_rx = ecoalesce->rx_max_coalesced_frames;
>  	if (ecoalesce->rx_coalesce_usecs)
> --
> 2.35.1.1320.gc452695387.dirty