6.16-stable review patch. If anyone has any objections, please let me know.
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From: Shahar Shitrit shshitrit@nvidia.com
[ Upstream commit e80d65561571db5024fbdd5ec3f5472cfc485d21 ]
mlx5e_reporter_rx_timeout() is currently invoked synchronously in the driver's open error flow. This causes the thread holding priv->state_lock to attempt acquiring the devlink lock, which can result in a circular dependency with other devlink operations.
For example:
- Devlink health diagnose flow: - __devlink_nl_pre_doit() acquires the devlink lock. - devlink_nl_health_reporter_diagnose_doit() invokes the driver's diagnose callback. - mlx5e_rx_reporter_diagnose() then attempts to acquire priv->state_lock.
- Driver open flow: - mlx5e_open() acquires priv->state_lock. - If an error occurs, devlink_health_reporter may be called, attempting to acquire the devlink lock.
To prevent this circular locking scenario, defer the RX timeout recovery by scheduling it via a workqueue. This ensures that the recovery work acquires locks in a consistent order: first the devlink lock, then priv->state_lock.
Additionally, make the recovery work acquire the netdev instance lock to safely synchronize with the open/close channel flows, similar to mlx5e_tx_timeout_work. Repeatedly attempt to acquire the netdev instance lock until it is taken or the target RQ is no longer active, as indicated by the MLX5E_STATE_CHANNELS_ACTIVE bit.
Fixes: 32c57fb26863 ("net/mlx5e: Report and recover from rx timeout") Signed-off-by: Shahar Shitrit shshitrit@nvidia.com Reviewed-by: Cosmin Ratiu cratiu@nvidia.com Reviewed-by: Dragos Tatulea dtatulea@nvidia.com Signed-off-by: Tariq Toukan tariqt@nvidia.com Link: https://patch.msgid.link/1753256672-337784-4-git-send-email-tariqt@nvidia.co... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/en.h | 1 + .../mellanox/mlx5/core/en/reporter_rx.c | 7 +++++ .../net/ethernet/mellanox/mlx5/core/en_main.c | 26 ++++++++++++++++++- 3 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h index 5b0d03b3efe8..48bcd6813aff 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h @@ -728,6 +728,7 @@ struct mlx5e_rq { struct xsk_buff_pool *xsk_pool;
struct work_struct recover_work; + struct work_struct rx_timeout_work;
/* control */ struct mlx5_wq_ctrl wq_ctrl; diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_rx.c index e75759533ae0..16c44d628eda 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_rx.c @@ -170,16 +170,23 @@ static int mlx5e_rx_reporter_err_rq_cqe_recover(void *ctx) static int mlx5e_rx_reporter_timeout_recover(void *ctx) { struct mlx5_eq_comp *eq; + struct mlx5e_priv *priv; struct mlx5e_rq *rq; int err;
rq = ctx; + priv = rq->priv; + + mutex_lock(&priv->state_lock); + eq = rq->cq.mcq.eq;
err = mlx5e_health_channel_eq_recover(rq->netdev, eq, rq->cq.ch_stats); if (err && rq->icosq) clear_bit(MLX5E_SQ_STATE_ENABLED, &rq->icosq->state);
+ mutex_unlock(&priv->state_lock); + return err; }
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c index ea822c69d137..16d818943487 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c @@ -707,6 +707,27 @@ static void mlx5e_rq_err_cqe_work(struct work_struct *recover_work) mlx5e_reporter_rq_cqe_err(rq); }
+static void mlx5e_rq_timeout_work(struct work_struct *timeout_work) +{ + struct mlx5e_rq *rq = container_of(timeout_work, + struct mlx5e_rq, + rx_timeout_work); + + /* Acquire netdev instance lock to synchronize with channel close and + * reopen flows. Either successfully obtain the lock, or detect that + * channels are closing for another reason, making this work no longer + * necessary. + */ + while (!netdev_trylock(rq->netdev)) { + if (!test_bit(MLX5E_STATE_CHANNELS_ACTIVE, &rq->priv->state)) + return; + msleep(20); + } + + mlx5e_reporter_rx_timeout(rq); + netdev_unlock(rq->netdev); +} + static int mlx5e_alloc_mpwqe_rq_drop_page(struct mlx5e_rq *rq) { rq->wqe_overflow.page = alloc_page(GFP_KERNEL); @@ -830,6 +851,7 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params,
rqp->wq.db_numa_node = node; INIT_WORK(&rq->recover_work, mlx5e_rq_err_cqe_work); + INIT_WORK(&rq->rx_timeout_work, mlx5e_rq_timeout_work);
if (params->xdp_prog) bpf_prog_inc(params->xdp_prog); @@ -1204,7 +1226,8 @@ int mlx5e_wait_for_min_rx_wqes(struct mlx5e_rq *rq, int wait_time) netdev_warn(rq->netdev, "Failed to get min RX wqes on Channel[%d] RQN[0x%x] wq cur_sz(%d) min_rx_wqes(%d)\n", rq->ix, rq->rqn, mlx5e_rqwq_get_cur_sz(rq), min_wqes);
- mlx5e_reporter_rx_timeout(rq); + queue_work(rq->priv->wq, &rq->rx_timeout_work); + return -ETIMEDOUT; }
@@ -1375,6 +1398,7 @@ void mlx5e_close_rq(struct mlx5e_rq *rq) if (rq->dim) cancel_work_sync(&rq->dim->work); cancel_work_sync(&rq->recover_work); + cancel_work_sync(&rq->rx_timeout_work); mlx5e_destroy_rq(rq); mlx5e_free_rx_descs(rq); mlx5e_free_rq(rq);