linux-kernel - [PATCH rdma-next] RDMA/mlx4: remove bogus dev_base

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Message-Id: <20201208193928.1500893-1-vladimir.oltean@nxp.com>
Date:   Tue,  8 Dec 2020 21:39:28 +0200
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Yishai Hadas <yishaih@...dia.com>,
        Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     netdev@...r.kernel.org, Leon Romanovsky <leonro@...dia.com>
Subject: [PATCH rdma-next] RDMA/mlx4: remove bogus dev_base_lock usage

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@...dia.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@....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