[PATCH 4.9 078/171] net/mlx5: Fix health work queue spin lock to IRQ safe

Greg Kroah-Hartman
2018-11-08T21:50:48Z

[ Upstream commit 6377ed0bbae6fa28853e1679d068a9106c8a8908 ]

spin_lock/unlock of health->wq_lock should be IRQ safe.
It was changed to spin_lock_irqsave since adding commit 0179720d6be2
("net/mlx5: Introduce trigger_health_work function") which uses
spin_lock from asynchronous event (IRQ) context.
Thus, all spin_lock/unlock of health->wq_lock should have been moved
to IRQ safe mode.
However, one occurrence on new code using this lock missed that
change, resulting in possible deadlock:
kernel: Possible unsafe locking scenario:
kernel: CPU0
kernel: ----
kernel: lock(&(&health->wq_lock)->rlock);
kernel: <Interrupt>
kernel: lock(&(&health->wq_lock)->rlock);
kernel: #012 *** DEADLOCK ***

Fixes: 2a0165a034ac ("net/mlx5: Cancel delayed recovery work when unloading the driver")
Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/mellanox/mlx5/core/health.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/health.c b/drivers/net/ethernet/mellanox/mlx5/core/health.c
index 448e71e07668..264f51b3409d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/health.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/health.c
@@ -369,10 +369,11 @@ void mlx5_drain_health_wq(struct mlx5_core_dev *dev)
void mlx5_drain_health_recovery(struct mlx5_core_dev *dev)
{
struct mlx5_core_health *health = &dev->priv.health;
+ unsigned long flags;

- spin_lock(&health->wq_lock);
+ spin_lock_irqsave(&health->wq_lock, flags);
set_bit(MLX5_DROP_NEW_RECOVERY_WORK, &health->flags);
- spin_unlock(&health->wq_lock);
+ spin_unlock_irqrestore(&health->wq_lock, flags);
cancel_delayed_work_sync(&dev->priv.health.recover_work);
}

--
2.17.1