[PATCH rdma-rc 2/3] RDMA/mlx5: Drain RCU callbacks during module teardown

[Leon Romanovsky]

From: Leon Romanovsky <leonro@xxxxxxxxxx>

devx_free_subscription() can remain queued after the last DevX event file
drops its module reference or an auxiliary driver detaches its devices.
mlx5_ib can then unload before the callback runs.

Registration error unwind has the same risk because driver registration
can attach existing devices before failing. Wait after all drivers have
stopped.

Fixes: 6898d1c661d7 ("RDMA/mlx5: Use RCU and direct refcounts to keep memory alive")
Reported-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Closes: https://lore.kernel.org/linux-rdma/20260708092316.Qb39F_B0@xxxxxxxxxxxxx/
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
---
 drivers/infiniband/hw/mlx5/main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 02809114fc79..4ff6cca7e581 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -5538,6 +5538,7 @@ static int __init mlx5_ib_init(void)
 dd_err:
 	mlx5r_rep_cleanup();
 rep_err:
+	rcu_barrier();
 	mlx5_ib_qp_event_cleanup();
 qp_event_err:
 	destroy_workqueue(mlx5_ib_event_wq);
@@ -5551,6 +5552,7 @@ static void __exit mlx5_ib_cleanup(void)
 	auxiliary_driver_unregister(&mlx5r_driver);
 	auxiliary_driver_unregister(&mlx5r_mp_driver);
 	mlx5r_rep_cleanup();
+	rcu_barrier();
 
 	mlx5_ib_qp_event_cleanup();
 	destroy_workqueue(mlx5_ib_event_wq);

-- 
2.54.0