Re: [PATCH net 3/5] eth: nfp: drop the replaced rule from the list when reprogramming fails

[Joe Damato <joe@dama.to>]

On Wed, Sep 02, 2026 at 08:26:09PM -0700, Jakub Kicinski wrote:
> nfp_net_fs_add() replaces an existing rule by deleting it from the
> hardware, decrementing nn->fs.count and programming the new one.  If
> nfp_net_fs_add_hw() fails the old entry stays on nn->fs.list - only the
> success path reaches list_replace() - so the list is one longer than
> nn->fs.count, and it advertises a rule whose hardware entry has already
> been torn down.
> 
> nn->fs.count is what ETHTOOL_GRXCLSRLCNT reports, so userspace then sizes
> its buffer one entry short of what the GRXCLSRLALL walk wants to write.
> That used to overwrite one u32 past the allocation; since the walk is
> bounded it is a permanent -EMSGSIZE instead, as nothing ever resyncs the
> counter.
> 
> Fixes: 9eb03bb1c035 ("nfp: add ethtool flow steering callbacks")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: leitao@debian.org
> CC: yinjun.zhang@corigine.com
> CC: louis.peens@corigine.com
> CC: oss-drivers@corigine.com
> ---
>  drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)

Reviewed-by: Joe Damato <joe@dama.to>