netdev - [PATCH net] net/mlx5: Don't fail driver on failure to create debugfs

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Date:   Tue,  2 Jun 2020 15:28:37 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Leon Romanovsky <leonro@...lanox.com>,
        clang-built-linux@...glegroups.com, linux-rdma@...r.kernel.org,
        Nathan Chancellor <natechancellor@...il.com>,
        netdev@...r.kernel.org, Saeed Mahameed <saeedm@...lanox.com>,
        Vu Pham <vuhuong@...lanox.com>
Subject: [PATCH net] net/mlx5: Don't fail driver on failure to create debugfs

From: Leon Romanovsky <leonro@...lanox.com>

Clang warns:

drivers/net/ethernet/mellanox/mlx5/core/main.c:1278:6: warning: variable
'err' is used uninitialized whenever 'if' condition is true
[-Wsometimes-uninitialized]
        if (!priv->dbg_root) {
            ^~~~~~~~~~~~~~~
drivers/net/ethernet/mellanox/mlx5/core/main.c:1303:9: note:
uninitialized use occurs here
        return err;
               ^~~
drivers/net/ethernet/mellanox/mlx5/core/main.c:1278:2: note: remove the
'if' if its condition is always false
        if (!priv->dbg_root) {
        ^~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/mellanox/mlx5/core/main.c:1259:9: note: initialize
the variable 'err' to silence this warning
        int err;
               ^
                = 0
1 warning generated.

The check of returned value of debugfs_create_dir() is wrong because
by the design debugfs failures should never fail the driver and the
check itself was wrong too. The kernel compiled without CONFIG_DEBUG_FS
will return ERR_PTR(-ENODEV) and not NULL as expected.

Fixes: 11f3b84d7068 ("net/mlx5: Split mdev init and pci init")
Link: https://github.com/ClangBuiltLinux/linux/issues/1042
Reported-by: Nathan Chancellor <natechancellor@...il.com>
Signed-off-by: Leon Romanovsky <leonro@...lanox.com>
---
Original discussion:
https://lore.kernel.org/lkml/20200530055447.1028004-1-natechancellor@gmail.com
---
 drivers/net/ethernet/mellanox/mlx5/core/main.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
index df46b1fce3a7..110e8d277d15 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
@@ -1275,11 +1275,6 @@ static int mlx5_mdev_init(struct mlx5_core_dev *dev, int profile_idx)

 	priv->dbg_root = debugfs_create_dir(dev_name(dev->device),
 					    mlx5_debugfs_root);
-	if (!priv->dbg_root) {
-		dev_err(dev->device, "mlx5_core: error, Cannot create debugfs dir, aborting\n");
-		goto err_dbg_root;
-	}
-
 	err = mlx5_health_init(dev);
 	if (err)
 		goto err_health_init;
--
2.26.2