Re: [PATCH net v2] gve: use gve_schedule_reset() on AdminQ flow rule timeout

On Fri, Aug 7, 2026 at 5:21 PM Rénich Bon Ćirić <[email protected]> wrote:
>
> When an AdminQ command to configure a flow rule times out in
> gve_adminq_configure_flow_rule(), the driver currently calls
> gve_reset(priv, true) synchronously.
>
> When flow rule configuration is invoked under netlink or ethtool
> callbacks, gve_reset() attempts to acquire rtnl_lock while already
> executing within an inner driver lock context. This violates the driver's
> lock hierarchy and causes an AB-BA circular lock inversion deadlock.
>
> Resolve this lock inversion by replacing synchronous gve_reset() with
> gve_schedule_reset(). This defers reset execution safely to
> gve_service_task out-of-band under the proper lock ordering.

gve_reset() does not acquire the rtnl_lock(). Also, there is no inner
driver lock context that is acquired at this point. The inner driver
lock context that the AI is complaining about is possibly
priv->adminq_lock but that is already released on error by
gve_adminq_execute_cmd(). gve_reset() is also written in such a way
that the onus is on the caller to acquire the appropriate locks -
either through the ethtool core when calling
gve_user_reset()/gve_set_rxnfc() or explicitly by gve_handle_reset().

Sashiko has also called out a few issues this change could introduce.
Considering this issue hasn't actually been encountered in the wild,
there is no lockdep splat and the commit message is inaccurate, I
don't think this qualifies for the net tree.

For the net-next tree, a more holistic change is in the works for the
reset path that also changes this path and removes the synchronous
reset anyway.

>
> Co-developed with Gemini AI (Google DeepMind) for root cause analysis
> and patch formulation.
>
> Fixes: 57718b60df9b ("gve: Add flow steering adminq commands")
> Reviewed-by: Przemek Kitszel <[email protected]>
> Signed-off-by: Rénich Bon Ćirić <[email protected]>
> ---
> v2: https://lore.kernel.org/netdev/[email protected]/
>   - Update Fixes tag to 57718b60df9b per Przemek Kitszel review.
>   - Add Reviewed-by tag from Przemek Kitszel.
>   - Remove misleading GitHub Issue #93 link (opened for CentOS Stream 10 NAPI bug).
>   - Add explicit AI co-development disclosure in commit body.
> v1: https://lore.kernel.org/netdev/[email protected]/
>
>  drivers/net/ethernet/google/gve/gve_adminq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
> index 08587bf12345..2037b1767890 100644
> --- a/drivers/net/ethernet/google/gve/gve_adminq.c
> +++ b/drivers/net/ethernet/google/gve/gve_adminq.c
> @@ -1322,7 +1322,7 @@ gve_adminq_configure_flow_rule(struct gve_priv *priv,
>
>         if (err == -ETIME) {
>                 dev_err(&priv->pdev->dev, "Timeout to configure the flow rule, trigger reset");
> -               gve_reset(priv, true);
> +               gve_schedule_reset(priv);
>         } else if (!err) {
>                 priv->flow_rules_cache.rules_cache_synced = false;
>         }
> --
> 2.45.2