RE: [PATCH 3.19.y-ckt 147/156] IB/mlx5: avoid destroying a NULL mr in reg_user_mr error flow

[Eli Cohen]

Acked-by: Eli Cohen <eli@xxxxxxxxxxxx>

-----Original Message-----
From: Kamal Mostafa [mailto:kamal@xxxxxxxxxxxxx] 
Sent: Tuesday, October 20, 2015 4:38 PM
To: linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; kernel-team@xxxxxxxxxxxxxxxx
Cc: Eli Cohen; Haggai Eran; Doug Ledford; Kamal Mostafa
Subject: [PATCH 3.19.y-ckt 147/156] IB/mlx5: avoid destroying a NULL mr in reg_user_mr error flow

3.19.8-ckt8 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Haggai Eran <haggaie@xxxxxxxxxxxx>

commit 11d748045c6dadb279d1acdb6d2ea8f3f2ede85b upstream.

The mlx5_ib_reg_user_mr() function will attempt to call clean_mr() in its error flow even though there is never a case where the error flow occurs with a valid MR pointer to destroy.

Remove the clean_mr() call and the incorrect comment above it.

Fixes: b4cfe447d47b ("IB/mlx5: Implement on demand paging by adding support for MMU notifiers")
Cc: Eli Cohen <eli@xxxxxxxxxxxx>
Signed-off-by: Haggai Eran <haggaie@xxxxxxxxxxxx>
Reviewed-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>

Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 drivers/infiniband/hw/mlx5/mr.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c index 32a28bd..e8b669f 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1118,19 +1118,7 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
 	return &mr->ibmr;
 
 error:
-	/*
-	 * Destroy the umem *before* destroying the MR, to ensure we
-	 * will not have any in-flight notifiers when destroying the
-	 * MR.
-	 *
-	 * As the MR is completely invalid to begin with, and this
-	 * error path is only taken if we can't push the mr entry into
-	 * the pagefault tree, this is safe.
-	 */
-
 	ib_umem_release(umem);
-	/* Kill the MR, and return an error code. */
-	clean_mr(mr);
 	return ERR_PTR(err);
 }
 
--
1.9.1

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