Re: [PATCH net-next] net: ethtool: Don't check if RSS context exists in case of context 0

[Joe Damato <jdamato@fastly.com>]

On Tue, Feb 25, 2025 at 09:13:48AM +0200, Gal Pressman wrote:
> Context 0 (default context) always exists, there is no need to check
> whether it exists or not when adding a flow steering rule.
> 
> The existing check fails when creating a flow steering rule for context
> 0 as it is not stored in the rss_ctx xarray.
> 
> For example:
> $ ethtool --config-ntuple eth2 flow-type tcp4 dst-ip 194.237.147.23 dst-port 19983 context 0 loc 618
> rmgr: Cannot insert RX class rule: Invalid argument
> Cannot insert classification rule
> 
> Fixes: de7f7582dff2 ("net: ethtool: prevent flow steering to RSS contexts which don't exist")
> Cc: Jakub Kicinski <kuba@kernel.org>
> Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
> Signed-off-by: Gal Pressman <gal@nvidia.com>
> ---
>  net/ethtool/ioctl.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 

I was initially confused why
tools/testing/selftests/drivers/net/hw/rss_ctx.py didn't catch this
bug, but if I'm reading the tests there correctly it doesn't test
this case AFAICT.

Do you think it's worth adding a test for this case as a separate
patch to net-next ?

That said, since context 0 isn't tracked in rss_ctx, the fix makes
sense to me:

Reviewed-by: Joe Damato <jdamato@fastly.com>