linux-kernel - Re: [PATCH] remoteproc: Don't bother checking the return value of debugfs

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Date:   Mon, 28 Mar 2022 09:51:23 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     bjorn.andersson@...aro.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] remoteproc: Don't bother checking the return value of
 debugfs_create*

Hi Mani,

On Thu, Mar 24, 2022 at 11:42:24PM +0530, Manivannan Sadhasivam wrote:
> DebugFS APIs are designed to return only the error pointers and not NULL
> in the case of failure. So these return pointers are safe to be passed on
> to the successive debugfs_create* APIs.
> 
> Therefore, let's just get rid of the checks.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/remoteproc/remoteproc_debugfs.c | 17 ++---------------
>  1 file changed, 2 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_debugfs.c b/drivers/remoteproc/remoteproc_debugfs.c
> index b5a1e3b697d9..2e2c4a31c154 100644
> --- a/drivers/remoteproc/remoteproc_debugfs.c
> +++ b/drivers/remoteproc/remoteproc_debugfs.c
> @@ -386,16 +386,8 @@ void rproc_remove_trace_file(struct dentry *tfile)
>  struct dentry *rproc_create_trace_file(const char *name, struct rproc *rproc,
>  				       struct rproc_debug_trace *trace)
>  {
> -	struct dentry *tfile;
> -
> -	tfile = debugfs_create_file(name, 0400, rproc->dbg_dir, trace,
> +	return debugfs_create_file(name, 0400, rproc->dbg_dir, trace,
>  				    &trace_rproc_ops);
> -	if (!tfile) {
> -		dev_err(&rproc->dev, "failed to create debugfs trace entry\n");
> -		return NULL;
> -	}
> -
> -	return tfile;

Please see this thread [1] for an earlier conversation on this topic.

[1]. https://lore.kernel.org/lkml/20220105131022.25247-1-linmq006@gmail.com/T/

>  }
>  
>  void rproc_delete_debug_dir(struct rproc *rproc)
> @@ -411,8 +403,6 @@ void rproc_create_debug_dir(struct rproc *rproc)
>  		return;
>  
>  	rproc->dbg_dir = debugfs_create_dir(dev_name(dev), rproc_dbg);
> -	if (!rproc->dbg_dir)
> -		return;
> 
>  	debugfs_create_file("name", 0400, rproc->dbg_dir,
>  			    rproc, &rproc_name_ops);
> @@ -430,11 +420,8 @@ void rproc_create_debug_dir(struct rproc *rproc)
>  
>  void __init rproc_init_debugfs(void)
>  {
> -	if (debugfs_initialized()) {
> +	if (debugfs_initialized())
>  		rproc_dbg = debugfs_create_dir(KBUILD_MODNAME, NULL);
> -		if (!rproc_dbg)
> -			pr_err("can't create debugfs dir\n");
> -	}

The above two are fine since debugfs_create_file() and debugfs_create_dir() can
deal with @parent being an error code.

Thanks,
Mathieu

>  }
>  
>  void __exit rproc_exit_debugfs(void)
> -- 
> 2.25.1
>