linux-kernel - Re: [PATCH 1/1] usb: xhci: Add debugfs interface for xHCI driver

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Date:   Sat, 29 Jul 2017 06:34:03 -0700
From:   Greg KH <greg@...ah.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Mathias Nyman <mathias.nyman@...ux.intel.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] usb: xhci: Add debugfs interface for xHCI driver

On Sat, Jul 29, 2017 at 04:18:03PM +0800, Lu Baolu wrote:
> +static void xhci_debugfs_create_files(struct xhci_hcd *xhci,
> +				      struct xhci_file_map *files,
> +				      size_t nentries, void *data,
> +				      struct dentry *parent,
> +				      const struct file_operations *fops)
> +{
> +	int			i;
> +	struct dentry		*file;
> +
> +	for (i = 0; i < nentries; i++) {
> +		file = debugfs_create_file(files[i].name, 0444,
> +					   parent, data, fops);
> +		if (IS_ERR_OR_NULL(file))
> +			break;

There's no need to ever check the return value of a debugfs_ function,
there's nothing you can do here, just keep calling it :)

And you will not get an error, you will only get NULL if there is an
error, as the only error you would get is if debugfs was not enabled.

> +static struct dentry *xhci_debugfs_create_ring_dir(struct xhci_hcd *xhci,
> +						   struct xhci_ring *ring,
> +						   const char *name,
> +						   struct dentry *parent)
> +{
> +	struct dentry		*dir;
> +
> +	dir = debugfs_create_dir(name, parent);
> +	if (IS_ERR_OR_NULL(dir))
> +		return NULL;

Same here.  Just keep going, you don't care about the return value, but
you can use it safely no matter what.


Same for other places in this patch as well.

thanks,

greg k-h