Re: [PATCH net v2] gve: use gve_schedule_reset() on AdminQ flow rule timeout
From: Harshitha Ramamurthy <hramamurthy@google.com>
Date: 2026-08-10 21:13:47
On Fri, Aug 7, 2026 at 5:21 PM Rénich Bon Ćirić [off-list ref] 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.
quoted hunk ↗ jump to hunk
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 <przemyslaw.kitszel@intel.com> Signed-off-by: Rénich Bon Ćirić <redacted> --- v2: https://lore.kernel.org/netdev/20260806085112.385934-1-renich@woralelandia.com/ (local) - 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/20260806085112.385934-1-renich@woralelandia.com/ (local) 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