netdev - Re: [PATCH v3 13/17] mvpp2: no need to check return value of debugfs

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Date:   Mon, 12 Aug 2019 10:55:51 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        Nathan Huckleberry <nhuck@...gle.com>
Subject: Re: [PATCH v3 13/17] mvpp2: no need to check return value of
 debugfs_create functions

On Sat, Aug 10, 2019 at 3:17 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.

Maybe adding this recommendation to the comment block above the
definition of debugfs_create_dir() in fs/debugfs/inode.c would help
prevent this issue in the future?  What failure means, and how to
proceed can be tricky; more documentation can only help in this
regard.

>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Maxime Chevallier <maxime.chevallier@...tlin.com>
> Cc: Nick Desaulniers <ndesaulniers@...gle.com>
> Cc: Nathan Huckleberry <nhuck@...gle.com>
> Cc: netdev@...r.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  .../ethernet/marvell/mvpp2/mvpp2_debugfs.c    | 19 +------------------
>  1 file changed, 1 insertion(+), 18 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c
> index 274fb07362cb..4a3baa7e0142 100644
> --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c
> +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c
> @@ -452,8 +452,6 @@ static int mvpp2_dbgfs_flow_port_init(struct dentry *parent,
>         struct dentry *port_dir;
>
>         port_dir = debugfs_create_dir(port->dev->name, parent);
> -       if (IS_ERR(port_dir))
> -               return PTR_ERR(port_dir);
>
>         port_entry = &port->priv->dbgfs_entries->port_flow_entries[port->id];
>
> @@ -480,8 +478,6 @@ static int mvpp2_dbgfs_flow_entry_init(struct dentry *parent,
>         sprintf(flow_entry_name, "%02d", flow);
>
>         flow_entry_dir = debugfs_create_dir(flow_entry_name, parent);
> -       if (!flow_entry_dir)
> -               return -ENOMEM;
>
>         entry = &priv->dbgfs_entries->flow_entries[flow];
>
> @@ -514,8 +510,6 @@ static int mvpp2_dbgfs_flow_init(struct dentry *parent, struct mvpp2 *priv)
>         int i, ret;
>
>         flow_dir = debugfs_create_dir("flows", parent);
> -       if (!flow_dir)
> -               return -ENOMEM;
>
>         for (i = 0; i < MVPP2_N_PRS_FLOWS; i++) {
>                 ret = mvpp2_dbgfs_flow_entry_init(flow_dir, priv, i);
> @@ -539,8 +533,6 @@ static int mvpp2_dbgfs_prs_entry_init(struct dentry *parent,
>         sprintf(prs_entry_name, "%03d", tid);
>
>         prs_entry_dir = debugfs_create_dir(prs_entry_name, parent);
> -       if (!prs_entry_dir)
> -               return -ENOMEM;
>
>         entry = &priv->dbgfs_entries->prs_entries[tid];
>
> @@ -578,8 +570,6 @@ static int mvpp2_dbgfs_prs_init(struct dentry *parent, struct mvpp2 *priv)
>         int i, ret;
>
>         prs_dir = debugfs_create_dir("parser", parent);
> -       if (!prs_dir)
> -               return -ENOMEM;
>
>         for (i = 0; i < MVPP2_PRS_TCAM_SRAM_SIZE; i++) {
>                 ret = mvpp2_dbgfs_prs_entry_init(prs_dir, priv, i);
> @@ -688,8 +678,6 @@ static int mvpp2_dbgfs_port_init(struct dentry *parent,
>         struct dentry *port_dir;
>
>         port_dir = debugfs_create_dir(port->dev->name, parent);
> -       if (IS_ERR(port_dir))
> -               return PTR_ERR(port_dir);
>
>         debugfs_create_file("parser_entries", 0444, port_dir, port,
>                             &mvpp2_dbgfs_port_parser_fops);
> @@ -716,15 +704,10 @@ void mvpp2_dbgfs_init(struct mvpp2 *priv, const char *name)
>         int ret, i;
>
>         mvpp2_root = debugfs_lookup(MVPP2_DRIVER_NAME, NULL);
> -       if (!mvpp2_root) {
> +       if (!mvpp2_root)
>                 mvpp2_root = debugfs_create_dir(MVPP2_DRIVER_NAME, NULL);
> -               if (IS_ERR(mvpp2_root))
> -                       return;
> -       }
>
>         mvpp2_dir = debugfs_create_dir(name, mvpp2_root);
> -       if (IS_ERR(mvpp2_dir))
> -               return;
>
>         priv->dbgfs_dir = mvpp2_dir;
>         priv->dbgfs_entries = kzalloc(sizeof(*priv->dbgfs_entries), GFP_KERNEL);
> --
> 2.22.0
>


-- 
Thanks,
~Nick Desaulniers