[PATCH net] net: ethtool: Fix RSS setting

[PATCH net] net: ethtool: Fix RSS setting

[Saeed Mahameed]

From: Saeed Mahameed <saeedm@nvidia.com>

When user submits a rxfh set command without touching XFRM_SYM_XOR,
rxfh.input_xfrm is set to RXH_XFRM_NO_CHANGE, which is equal to 0xff.

Testing if (rxfh.input_xfrm & RXH_XFRM_SYM_XOR &&
	    !ops->cap_rss_sym_xor_supported)
		return -EOPNOTSUPP;

Will always be true on devices that don't set cap_rss_sym_xor_supported,
since rxfh.input_xfrm & RXH_XFRM_SYM_XOR is always true, if input_xfrm
was not set, i.e RXH_XFRM_NO_CHANGE=0xff, which will result in failure
of any command that doesn't require any change of XFRM, e.g RSS context
or hash function changes.

To avoid this breakage, test if rxfh.input_xfrm != RXH_XFRM_NO_CHANGE
before testing other conditions.

Fixes: 13e59344fb9d ("net: ethtool: add support for symmetric-xor RSS hash")
CC: Ahmed Zaki <ahmed.zaki@intel.com>
CC: David Wei <dw@davidwei.uk>,
CC: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
---
 net/ethtool/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index e645d751a5e8..223dcd25d88a 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1306,7 +1306,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	if (rxfh.input_xfrm && rxfh.input_xfrm != RXH_XFRM_SYM_XOR &&
 	    rxfh.input_xfrm != RXH_XFRM_NO_CHANGE)
 		return -EINVAL;
-	if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
+	if (rxfh.input_xfrm != RXH_XFRM_NO_CHANGE &&
+	    (rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
 	    !ops->cap_rss_sym_xor_supported)
 		return -EOPNOTSUPP;
 
-- 
2.45.2

Re: [PATCH net] net: ethtool: Fix RSS setting

[Ahmed Zaki]

On 2024-07-10 4:55 p.m., Saeed Mahameed wrote:
> From: Saeed Mahameed <saeedm@nvidia.com>
> 
> When user submits a rxfh set command without touching XFRM_SYM_XOR,
> rxfh.input_xfrm is set to RXH_XFRM_NO_CHANGE, which is equal to 0xff.
> 
> Testing if (rxfh.input_xfrm & RXH_XFRM_SYM_XOR &&
> 	    !ops->cap_rss_sym_xor_supported)
> 		return -EOPNOTSUPP;
> 
> Will always be true on devices that don't set cap_rss_sym_xor_supported,
> since rxfh.input_xfrm & RXH_XFRM_SYM_XOR is always true, if input_xfrm
> was not set, i.e RXH_XFRM_NO_CHANGE=0xff, which will result in failure
> of any command that doesn't require any change of XFRM, e.g RSS context
> or hash function changes.
> 
> To avoid this breakage, test if rxfh.input_xfrm != RXH_XFRM_NO_CHANGE
> before testing other conditions.
> 
> Fixes: 13e59344fb9d ("net: ethtool: add support for symmetric-xor RSS hash")
> CC: Ahmed Zaki <ahmed.zaki@intel.com>
> CC: David Wei <dw@davidwei.uk>,
> CC: Pavel Begunkov <asml.silence@gmail.com>
> Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
> ---
>   net/ethtool/ioctl.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
> index e645d751a5e8..223dcd25d88a 100644
> --- a/net/ethtool/ioctl.c
> +++ b/net/ethtool/ioctl.c
> @@ -1306,7 +1306,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
>   	if (rxfh.input_xfrm && rxfh.input_xfrm != RXH_XFRM_SYM_XOR &&
>   	    rxfh.input_xfrm != RXH_XFRM_NO_CHANGE)
>   		return -EINVAL;
> -	if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
> +	if (rxfh.input_xfrm != RXH_XFRM_NO_CHANGE &&
> +	    (rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
>   	    !ops->cap_rss_sym_xor_supported)
>   		return -EOPNOTSUPP;
>   

LGTM, thank you for catching this.

Reviewed-by: Ahmed Zaki <ahmed.zaki@intel.com>

Re: [PATCH net] net: ethtool: Fix RSS setting

[Jakub Kicinski]

On Wed, 10 Jul 2024 15:55:38 -0700 Saeed Mahameed wrote:
> Fixes: 13e59344fb9d ("net: ethtool: add support for symmetric-xor RSS hash")

I think :

Fixes: 0dd415d15505 ("net: ethtool: add a NO_CHANGE uAPI for new RXFH's input_xfrm")

will swap when applying.

Re: [PATCH net] net: ethtool: Fix RSS setting

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 10 Jul 2024 15:55:38 -0700 you wrote:
> From: Saeed Mahameed <saeedm@nvidia.com>
> 
> When user submits a rxfh set command without touching XFRM_SYM_XOR,
> rxfh.input_xfrm is set to RXH_XFRM_NO_CHANGE, which is equal to 0xff.
> 
> Testing if (rxfh.input_xfrm & RXH_XFRM_SYM_XOR &&
> 	    !ops->cap_rss_sym_xor_supported)
> 		return -EOPNOTSUPP;
> 
> [...]

Here is the summary with links:
  - [net] net: ethtool: Fix RSS setting
    https://git.kernel.org/netdev/net/c/503757c80928

You are awesome, thank you!
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