[PATCH rdma-next 9/9] RDMA/mlx5: Drop FRMR pool handle on UMR revoke failure

[Michael Gur <michaelgur@nvidia.com>]

From: Michael Guralnik <michaelgur@nvidia.com>

When UMR revoke fails during MR cleanup, the handle is left in an
unknown state and cannot be returned to the pool. The driver already
destroys the mkey via the fallback path, but the pool's in_use counter
is never decremented, drifting upward over time.

Call ib_frmr_pool_drop on the revoke-failure path so the pool's
accounting stays consistent with the handles it has handed out.

Fixes: 36680ef7bceb ("RDMA/mlx5: Switch from MR cache to FRMR pools")
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
---
 drivers/infiniband/hw/mlx5/mr.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 1a6a8ccf6832..067e80f7875b 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1379,9 +1379,11 @@ static int mlx5r_handle_mkey_cleanup(struct mlx5_ib_mr *mr)
 	bool is_odp = is_odp_mr(mr);
 	int ret;
 
-	if (mr->ibmr.frmr.pool && !mlx5_umr_revoke_mr_with_lock(mr)) {
-		ib_frmr_pool_push(mr->ibmr.device, &mr->ibmr);
-		return 0;
+	if (mr->ibmr.frmr.pool) {
+		if (!mlx5_umr_revoke_mr_with_lock(mr)) {
+			ib_frmr_pool_push(mr->ibmr.device, &mr->ibmr);
+			return 0;
+		}
 	}
 
 	if (is_odp)
@@ -1403,6 +1405,10 @@ static int mlx5r_handle_mkey_cleanup(struct mlx5_ib_mr *mr)
 		dma_resv_unlock(
 			to_ib_umem_dmabuf(mr->umem)->attach->dmabuf->resv);
 	}
+
+	if (mr->ibmr.frmr.pool && !ret)
+		ib_frmr_pool_drop(&mr->ibmr);
+
 	return ret;
 }
 
-- 
2.52.0