linux-kernel - RE: [PATCH v3 1/2] usb: dwc3: make dwc3_debugfs

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Date:	Mon, 11 Apr 2016 14:23:21 +0300
From:	Felipe Balbi <balbi@...nel.org>
To:	"Du\, Changbin" <changbin.du@...el.com>
Cc:	"gregkh\@linuxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb\@vger.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 1/2] usb: dwc3: make dwc3_debugfs_init return value be void


Hi,

"Du, Changbin" <changbin.du@...el.com> writes:
>> >  	root = debugfs_create_dir(dev_name(dwc->dev), NULL);
>> > -	if (!root) {
>> > -		ret = -ENOMEM;
>> > -		goto err0;
>> > -	}
>> > +	if (IS_ERR_OR_NULL(root))
>> > +		return;
>> 
>> We can definitely keep on going, but I'd still like to know that we
>> enabled CONFIG_DEBUG_FS but failed to create a file or a
>> directory. Seems like this should read as follows:
>> 
>> 	if (IS_ERR_OR_NULL(root)) {
>>         	if (!root)
>>                 	dev_err(dwc->dev, "Can't create debugfs root\n");
>>         	return;
>> 	}
>> 
>> ditto to all bellow.
>> 
> Balbi, so you mean we should not let the failure go silent,  right?

yeah, but only iff CONFIG_DEBUG_FS is enabled. From what I can tell, in
case CONFIG_DEBUG_FS is enabled and it fails, it'll return a NULL
pointer instead of ERR_PTR() ;-)

>> >  	dwc->root = root;
>> >
>> >  	dwc->regset = kzalloc(sizeof(*dwc->regset), GFP_KERNEL);
>> >  	if (!dwc->regset) {
>> > -		ret = -ENOMEM;
>> > -		goto err1;
>> > +		debugfs_remove_recursive(root);
>> 
>> you're now duplicating debugfs_remove_recursive(root) in all braches and
>> that's error prone. It's probably better to keep our gotos, but change
>> them so they read as follows:
>> 
>> 	if (!dwc->regset)
>>         	goto err1;
>> 
>> 	[...]
>> 
>>         return; /* this is our successful exit point */
>> 
>> err1:
>> 	debugfs_remove_recursive(root);
>>         kfree(dwc->regset);
>> 
>> 
>> --
>> Balbi
>
> No, no need anymore. Because no branch share this code now.
> Then remove the goto would make code a little clear.

fair enough.

-- 
balbi

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