netdev - Re: [PATCH net-next v2] gve: Add RSS cache for non RSS device option scenario

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Message-ID: <CAG-FcCMAT7Bvmxgo1aJh+Bv=z8MJKJN9LyzxOBuQVNMO2A=2qQ@mail.gmail.com>
Date: Wed, 5 Feb 2025 22:26:38 -0800
From: Ziwei Xiao <ziweixiao@...gle.com>
To: Simon Horman <horms@...nel.org>
Cc: Jeroen de Borst <jeroendb@...gle.com>, netdev@...r.kernel.org, davem@...emloft.net, 
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, 
	pkaligineedi@...gle.com, shailend@...gle.com, andrew+netdev@...n.ch, 
	willemb@...gle.com, hramamurthy@...gle.com, linux-kernel@...r.kernel.org, 
	Jeroen de Borst <jeroend@...gle.com>
Subject: Re: [PATCH net-next v2] gve: Add RSS cache for non RSS device option scenario

On Wed, Feb 5, 2025 at 8:28 AM Simon Horman <horms@...nel.org> wrote:
>
> On Tue, Feb 04, 2025 at 01:31:21PM -0800, Jeroen de Borst wrote:
> > From: Ziwei Xiao <ziweixiao@...gle.com>
> >
> > Not all the devices have the capability for the driver to query for the
> > registered RSS configuration. The driver can discover this by checking
> > the relevant device option during setup. If it cannot, the driver needs
> > to store the RSS config cache and directly return such cache when
> > queried by the ethtool. RSS config is inited when driver probes. Also the
> > default RSS config will be adjusted when there is RX queue count change.
> >
> > At this point, only keys of GVE_RSS_KEY_SIZE and indirection tables of
> > GVE_RSS_INDIR_SIZE are supported.
> >
> > Signed-off-by: Ziwei Xiao <ziweixiao@...gle.com>
> > Reviewed-by: Harshitha Ramamurthy <hramamurthy@...gle.com>
> > Reviewed-by: Willem de Bruijn <willemb@...gle.com>
> > Signed-off-by: Praveen Kaligineedi <pkaligineedi@...gle.com>
> > Signed-off-by: Jeroen de Borst <jeroend@...gle.com>
> > ---
> > Changes in v2:
> >  - Change to initialize RSS config when the driver is up instead of
> >    doing that when the user setting the RSS.(Jakub Kicinski)
> >  - Use NL_SET_ERR_MSG_MOD to log errors when there is extack
> >    available.(Jakub Kicinski)
> >  - Use ethtool_rxfh_indir_default to set default RSS indir
> >    table.(Jakub Kicinski)
> >  - Adjust the default RSS config when there is RX queue count change to
> >    ensure the default RSS config is correct.
> >
> >  drivers/net/ethernet/google/gve/gve.h         | 16 +++-
> >  drivers/net/ethernet/google/gve/gve_adminq.c  | 64 ++++++++++---
> >  drivers/net/ethernet/google/gve/gve_ethtool.c | 60 ++++++++++--
> >  drivers/net/ethernet/google/gve/gve_main.c    | 92 ++++++++++++++++++-
> >  4 files changed, 209 insertions(+), 23 deletions(-)
>
> ...
>
> > diff --git a/drivers/net/ethernet/google/gve/gve_ethtool.c b/drivers/net/ethernet/google/gve/gve_ethtool.c
> > index bdfc6e77b2af..efcafc607b2a 100644
> > --- a/drivers/net/ethernet/google/gve/gve_ethtool.c
> > +++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
> > @@ -482,6 +482,7 @@ static int gve_set_channels(struct net_device *netdev,
> >       struct ethtool_channels old_settings;
> >       int new_tx = cmd->tx_count;
> >       int new_rx = cmd->rx_count;
> > +     bool reset_rss;
> >
> >       gve_get_channels(netdev, &old_settings);
> >
> > @@ -498,16 +499,14 @@ static int gve_set_channels(struct net_device *netdev,
> >               return -EINVAL;
> >       }
> >
> > -     if (!netif_running(netdev)) {
> > -             priv->tx_cfg.num_queues = new_tx;
> > -             priv->rx_cfg.num_queues = new_rx;
> > -             return 0;
> > -     }
> > +     if (new_rx != priv->rx_cfg.num_queues &&
> > +         priv->cache_rss_config && !netif_is_rxfh_configured(netdev))
> > +             reset_rss = true;
>
> Hi Jerome,
>
> This is not a full review (which I was working on but ran out of time for now).
> But, if the condition above is not met then reset_rss will be used
> uninitialised below.
>
> Flagged by W=1 build with clang-19.
>
Thank you for pointing that out. Will fix it on the V3 patch.
> >
> >       new_tx_cfg.num_queues = new_tx;
> >       new_rx_cfg.num_queues = new_rx;
> >
> > -     return gve_adjust_queues(priv, new_rx_cfg, new_tx_cfg);
> > +     return gve_adjust_queues(priv, new_rx_cfg, new_tx_cfg, reset_rss);
> >  }
> >
> >  static void gve_get_ringparam(struct net_device *netdev,
>
> ...
>
> --
> pw-bot: cr