* [PATCH rdma-next] RDMA/mlx4: remove bogus dev_base_lock usage
@ 2020-12-08 19:39 Vladimir Oltean
2020-12-10 21:08 ` Jason Gunthorpe
0 siblings, 1 reply; 2+ messages in thread
From: Vladimir Oltean @ 2020-12-08 19:39 UTC (permalink / raw)
To: Yishai Hadas, Doug Ledford, Jason Gunthorpe, linux-rdma,
linux-kernel
Cc: netdev, Leon Romanovsky
It is not clear what this lock protects. If the authors wanted to ensure
that "dev" does not disappear, that is impossible, given the following
code path:
mlx4_ib_netdev_event (under RTNL mutex)
-> mlx4_ib_scan_netdevs
-> mlx4_ib_update_qps
Also, the dev_base_lock does not protect dev->dev_addr either.
So it serves no purpose here. Remove it.
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
drivers/infiniband/hw/mlx4/main.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
index f0864f40ea1a..e3cd402c079a 100644
--- a/drivers/infiniband/hw/mlx4/main.c
+++ b/drivers/infiniband/hw/mlx4/main.c
@@ -2265,10 +2265,7 @@ static void mlx4_ib_update_qps(struct mlx4_ib_dev *ibdev,
u64 release_mac = MLX4_IB_INVALID_MAC;
struct mlx4_ib_qp *qp;
- read_lock(&dev_base_lock);
new_smac = mlx4_mac_to_u64(dev->dev_addr);
- read_unlock(&dev_base_lock);
-
atomic64_set(&ibdev->iboe.mac[port - 1], new_smac);
/* no need for update QP1 and mac registration in non-SRIOV */
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH rdma-next] RDMA/mlx4: remove bogus dev_base_lock usage
2020-12-08 19:39 [PATCH rdma-next] RDMA/mlx4: remove bogus dev_base_lock usage Vladimir Oltean
@ 2020-12-10 21:08 ` Jason Gunthorpe
0 siblings, 0 replies; 2+ messages in thread
From: Jason Gunthorpe @ 2020-12-10 21:08 UTC (permalink / raw)
To: Vladimir Oltean
Cc: Yishai Hadas, Doug Ledford, linux-rdma, linux-kernel, netdev,
Leon Romanovsky
On Tue, Dec 08, 2020 at 09:39:28PM +0200, Vladimir Oltean wrote:
> It is not clear what this lock protects. If the authors wanted to ensure
> that "dev" does not disappear, that is impossible, given the following
> code path:
>
> mlx4_ib_netdev_event (under RTNL mutex)
> -> mlx4_ib_scan_netdevs
> -> mlx4_ib_update_qps
>
> Also, the dev_base_lock does not protect dev->dev_addr either.
>
> So it serves no purpose here. Remove it.
>
> Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
> drivers/infiniband/hw/mlx4/main.c | 3 ---
> 1 file changed, 3 deletions(-)
Applied to for-next, thanks
Jason
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-12-08 19:39 [PATCH rdma-next] RDMA/mlx4: remove bogus dev_base_lock usage Vladimir Oltean
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