[PATCH 5.12 037/178] Revert "net/mlx5: Arm only EQs with EQEs"

Greg Kroah-Hartman
2021-06-21T16:38:59Z

From: Shay Drory <shayd@nvidia.com>

[ Upstream commit 7a545077cb6701957e84c7f158630bb5c984e648 ]

In the scenario described below, an EQ can remain in FIRED state which
can result in missing an interrupt generation.

The scenario:

device mlx5_core driver
------ ----------------
EQ1.eqe generated
EQ1.MSI-X sent
EQ1.state = FIRED
EQ2.eqe generated
mlx5_irq()
polls - eq1_eqes()
arm eq1
polls - eq2_eqes()
arm eq2
EQ2.MSI-X sent
EQ2.state = FIRED
mlx5_irq()
polls - eq2_eqes() -- no eqes found
driver skips EQ arming;

->EQ2 remains fired, misses generating interrupt.

Hence, always arm the EQ by reverting the cited commit in fixes tag.

Fixes: d894892dda25 ("net/mlx5: Arm only EQs with EQEs")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/mellanox/mlx5/core/eq.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eq.c b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
index 1fa9c18563da..31c6a3b91f4a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eq.c
@@ -136,7 +136,7 @@ static int mlx5_eq_comp_int(struct notifier_block *nb,

eqe = next_eqe_sw(eq);
if (!eqe)
- return 0;
+ goto out;

do {
struct mlx5_core_cq *cq;
@@ -161,6 +161,8 @@ static int mlx5_eq_comp_int(struct notifier_block *nb,
++eq->cons_index;

} while ((++num_eqes < MLX5_EQ_POLLING_BUDGET) && (eqe = next_eqe_sw(eq)));
+
+out:
eq_update_ci(eq, 1);

if (cqn != -1)
@@ -248,9 +250,9 @@ static int mlx5_eq_async_int(struct notifier_block *nb,
++eq->cons_index;

} while ((++num_eqes < MLX5_EQ_POLLING_BUDGET) && (eqe = next_eqe_sw(eq)));
- eq_update_ci(eq, 1);

out:
+ eq_update_ci(eq, 1);
mlx5_eq_async_int_unlock(eq_async, recovery, &flags);

return unlikely(recovery) ? num_eqes : 0;
--
2.30.2