linux-kernel - Re: [PATCH v6] USB hub_probe: rework ugly goto-into-compound-statement

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Date:   Mon, 21 Nov 2016 17:33:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Eugene Korenevsky <ekorenevsky@...il.com>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        Baolin Wang <baolin.wang@...aro.org>
Subject: Re: [PATCH v6] USB hub_probe: rework ugly
 goto-into-compound-statement

On Sat, Nov 19, 2016 at 09:55:45AM +0300, Eugene Korenevsky wrote:
> Rework smelling code (goto inside compound statement). Perhaps this is
> legacy. Anyway such code is not appropriate for Linux kernel.
> 
> Signed-off-by: Eugene Korenevsky <ekorenevsky@...il.com>
> ---
> Changes in v6: more pedantic conversion from `int` to `bool`; fix comment
> Changes in v5: make `bool` a return type of `hub_check_descriptor_sanity()`
> Changes in v4: fix typo
> Changes in v3: extract the code to static function
> Changes in v2: fix spaces instead of tab, add missing 'Signed-off-by'
> 
>  drivers/usb/core/hub.c | 38 +++++++++++++++++++++-----------------
>  1 file changed, 21 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index cbb1467..dbebfe4 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -1722,10 +1722,28 @@ static void hub_disconnect(struct usb_interface *intf)
>  	kref_put(&hub->kref, hub_release);
>  }
>  
> +static bool hub_check_descriptor_sanity(struct usb_host_interface *desc)
> +{
> +	/* Some hubs have a subclass of 1, which AFAICT according to the */
> +	/*  specs is not defined, but it works */
> +	if (desc->desc.bInterfaceSubClass != 0 &&
> +	    desc->desc.bInterfaceSubClass != 1)
> +		return false;
> +
> +	/* Multiple endpoints? What kind of mutant ninja-hub is this? */
> +	if (desc->desc.bNumEndpoints != 1)
> +		return false;
> +
> +	/* If the first endpoint is not interrupt IN, we'd better punt! */
> +	if (!usb_endpoint_is_int_in(&desc->endpoint[0].desc))
> +		return false;
> +
> +        return true;
> +}
> +
>  static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
>  {
>  	struct usb_host_interface *desc;
> -	struct usb_endpoint_descriptor *endpoint;
>  	struct usb_device *hdev;
>  	struct usb_hub *hub;
>  
> @@ -1800,25 +1818,11 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
>  	}
>  #endif
>  
> -	/* Some hubs have a subclass of 1, which AFAICT according to the */
> -	/*  specs is not defined, but it works */
> -	if ((desc->desc.bInterfaceSubClass != 0) &&
> -	    (desc->desc.bInterfaceSubClass != 1)) {
> -descriptor_error:
> +	if (!hub_check_descriptor_sanity(desc)) {

Read that line out loud please, and tell me it makes sense:
	If not hub_check_descriptor_sanity().

Doesn't:
	If not hub_descriptor_is_sane()
make more sense?

thanks,

greg k-h