linux-kernel - Re: [PATCH 6/7] crypto: ccp: no need to check return value of debugfs

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Date:   Tue, 22 Jan 2019 22:06:54 +0000
From:   Gary R Hook <ghook@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        David Miller <davem@...emloft.net>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        "Hook, Gary" <Gary.Hook@....com>
Subject: Re: [PATCH 6/7] crypto: ccp: no need to check return value of
 debugfs_create functions

On 1/22/19 9:14 AM, Greg Kroah-Hartman 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.

Stupid question(s) time.

If we don't care about failures (because the subsystem handles them 
without our involvement) why do these functions even have return values? 
Why haven't they been changed to void so that they reflect the current 
style of intended use?

I realize I'm old fashioned, but if a failure occurs, I've always been 
of a mind to kick out and not try to do any further work. But debugfs is 
to be treated as an exception to that paradigm? Carry on, ignore errors, 
don't worry about it?

That said,

Acked-by: Gary R Hook <gary.hook@....com>

> 
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: Gary Hook <gary.hook@....com>
> Cc: Herbert Xu <herbert@...dor.apana.org.au>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: linux-crypto@...r.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>   drivers/crypto/ccp/ccp-debugfs.c | 36 +++++++-------------------------
>   1 file changed, 7 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/crypto/ccp/ccp-debugfs.c b/drivers/crypto/ccp/ccp-debugfs.c
> index 1a734bd2070a..4bd26af7098d 100644
> --- a/drivers/crypto/ccp/ccp-debugfs.c
> +++ b/drivers/crypto/ccp/ccp-debugfs.c
> @@ -286,10 +286,7 @@ void ccp5_debugfs_setup(struct ccp_device *ccp)
>   {
>   	struct ccp_cmd_queue *cmd_q;
>   	char name[MAX_NAME_LEN + 1];
> -	struct dentry *debugfs_info;
> -	struct dentry *debugfs_stats;
>   	struct dentry *debugfs_q_instance;
> -	struct dentry *debugfs_q_stats;
>   	int i;
>   
>   	if (!debugfs_initialized())
> @@ -299,24 +296,14 @@ void ccp5_debugfs_setup(struct ccp_device *ccp)
>   	if (!ccp_debugfs_dir)
>   		ccp_debugfs_dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
>   	mutex_unlock(&ccp_debugfs_lock);
> -	if (!ccp_debugfs_dir)
> -		return;
>   
>   	ccp->debugfs_instance = debugfs_create_dir(ccp->name, ccp_debugfs_dir);
> -	if (!ccp->debugfs_instance)
> -		goto err;
>   
> -	debugfs_info = debugfs_create_file("info", 0400,
> -					   ccp->debugfs_instance, ccp,
> -					   &ccp_debugfs_info_ops);
> -	if (!debugfs_info)
> -		goto err;
> +	debugfs_create_file("info", 0400, ccp->debugfs_instance, ccp,
> +			    &ccp_debugfs_info_ops);
>   
> -	debugfs_stats = debugfs_create_file("stats", 0600,
> -					    ccp->debugfs_instance, ccp,
> -					    &ccp_debugfs_stats_ops);
> -	if (!debugfs_stats)
> -		goto err;
> +	debugfs_create_file("stats", 0600, ccp->debugfs_instance, ccp,
> +			    &ccp_debugfs_stats_ops);
>   
>   	for (i = 0; i < ccp->cmd_q_count; i++) {
>   		cmd_q = &ccp->cmd_q[i];
> @@ -325,21 +312,12 @@ void ccp5_debugfs_setup(struct ccp_device *ccp)
>   
>   		debugfs_q_instance =
>   			debugfs_create_dir(name, ccp->debugfs_instance);
> -		if (!debugfs_q_instance)
> -			goto err;
> -
> -		debugfs_q_stats =
> -			debugfs_create_file("stats", 0600,
> -					    debugfs_q_instance, cmd_q,
> -					    &ccp_debugfs_queue_ops);
> -		if (!debugfs_q_stats)
> -			goto err;
> +
> +		debugfs_create_file("stats", 0600, debugfs_q_instance, cmd_q,
> +				    &ccp_debugfs_queue_ops);
>   	}
>   
>   	return;
> -
> -err:
> -	debugfs_remove_recursive(ccp->debugfs_instance);
>   }
>   
>   void ccp5_debugfs_destroy(void)
>