netdev - [PATCH net-next] net/mlx5: Devcom, only use devcom after NULL check in mlx5_devcom_send

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Date: Fri, 4 Aug 2023 17:26:36 +0800
From: Li Zetao <lizetao1@...wei.com>
To: <saeedm@...dia.com>, <leon@...nel.org>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>
CC: <lizetao1@...wei.com>, <pabeni@...hat.com>, <shayd@...dia.com>,
	<roid@...dia.com>, <mbloch@...dia.com>, <vladbu@...dia.com>,
	<elic@...dia.com>, <netdev@...r.kernel.org>, <linux-rdma@...r.kernel.org>
Subject: [PATCH net-next] net/mlx5: Devcom, only use devcom after NULL check in mlx5_devcom_send_event()

There is a warning reported by kernel test robot:

smatch warnings:
drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c:264
    mlx5_devcom_send_event() warn: variable dereferenced before
	IS_ERR check devcom (see line 259)

The reason for the warning is that the pointer is used before check, put
the assignment to comp after devcom check to silence the warning.

Fixes: 88d162b47981 ("net/mlx5: Devcom, Infrastructure changes")
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <error27@...il.com>
Closes: https://lore.kernel.org/r/202308041028.AkXYDwJ6-lkp@intel.com/
Signed-off-by: Li Zetao <lizetao1@...wei.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c
index feb62d952643..2bc18274858c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c
@@ -256,7 +256,7 @@ int mlx5_devcom_send_event(struct mlx5_devcom_comp_dev *devcom,
 			   int event, int rollback_event,
 			   void *event_data)
 {
-	struct mlx5_devcom_comp *comp = devcom->comp;
+	struct mlx5_devcom_comp *comp;
 	struct mlx5_devcom_comp_dev *pos;
 	int err = 0;
 	void *data;
@@ -264,6 +264,7 @@ int mlx5_devcom_send_event(struct mlx5_devcom_comp_dev *devcom,
 	if (IS_ERR_OR_NULL(devcom))
 		return -ENODEV;
 
+	comp = devcom->comp;
 	down_write(&comp->sem);
 	list_for_each_entry(pos, &comp->comp_dev_list_head, list) {
 		data = rcu_dereference_protected(pos->data, lockdep_is_held(&comp->sem));
-- 
2.34.1