linux-kernel - Re: [PATCH 6/6] dma: qcom: hidma: no need to check return value of debugfs

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Date:   Wed, 12 Jun 2019 17:39:48 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Sinan Kaya <Okaya@...nel.org>
Cc:     dan.j.williams@...el.com, vkoul@...nel.org,
        Andy Gross <agross@...nel.org>,
        David Brown <david.brown@...aro.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] dma: qcom: hidma: no need to check return value of
 debugfs_create functions

On Wed, Jun 12, 2019 at 11:24:51AM -0400, Sinan Kaya wrote:
> On 6/12/2019 8:25 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.
> > 
> > Also, because there is no need to save the file dentry, remove the
> > variables that were saving them as they were never even being used once
> > set.
> > 
> > Cc: Sinan Kaya <okaya@...nel.org>
> > Cc: Andy Gross <agross@...nel.org>
> > Cc: David Brown <david.brown@...aro.org>
> > Cc: Dan Williams <dan.j.williams@...el.com>
> > Cc: Vinod Koul <vkoul@...nel.org>
> > Cc: linux-arm-kernel@...ts.infradead.org
> > Cc: linux-arm-msm@...r.kernel.org
> > Cc: dmaengine@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> 
> Interesting. Wouldn't debugfs_create_file() blow up if dir is NULL
> for some reason?

It will create a file in the root of debugfs.  But how will that happen?
debugfs_create_dir() can not return NULL.

> +		debugfs_create_file("stats", S_IRUGO, dir, chan,
> +				    &hidma_chan_fops);
> 
> Note that code ignores the return value of hidma_debug_init();
> It was just trying to do clean up on debugfs failure by calling
> 
> 	debugfs_remove_recursive(dmadev->debugfs);

Is that a problem?

thanks,

greg k-h