netdev - [PATCH -next v2] net/mlx5: Devcom, only use devcom after NULL check in mlx5_devcom_send

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Date: Mon, 14 Aug 2023 15:23:42 +0800
From: Li Zetao <lizetao1@...wei.com>
To: <vadim.fedorenko@...ux.dev>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <elic@...dia.com>,
	<kuba@...nel.org>, <leon@...nel.org>, <linux-rdma@...r.kernel.org>,
	<lizetao1@...wei.com>, <mbloch@...dia.com>, <netdev@...r.kernel.org>,
	<pabeni@...hat.com>, <roid@...dia.com>, <saeedm@...dia.com>,
	<shayd@...dia.com>, <vladbu@...dia.com>, kernel test robot <lkp@...el.com>,
	Dan Carpenter <error27@...il.com>
Subject: [PATCH -next v2] 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>
---
v1 -> v2: Modify the order of variable declarations to end up with reverse x-mas tree order.
v1: https://lore.kernel.org/all/20230804092636.91357-1-lizetao1@huawei.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..00e67910e3ee 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c
@@ -256,14 +256,15 @@ 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_dev *pos;
+	struct mlx5_devcom_comp *comp;
 	int err = 0;
 	void *data;
 
 	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