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

[Greg Kroah-Hartman]

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 
> ---
> 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(>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(>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
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[PATCH v6] USB hub_probe: rework ugly goto-into-compound-statement

[Eugene Korenevsky]

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 
---
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(>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(>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)) {
dev_err(>dev, "bad descriptor, ignoring hub\n");
return -EIO;
}
 
-   /* Multiple endpoints? What kind of mutant ninja-hub is this? */
-   if (desc->desc.bNumEndpoints != 1)
-   goto descriptor_error;
-
-   endpoint = >endpoint[0].desc;
-
-   /* If it's not an interrupt in endpoint, we'd better punt! */
-   if (!usb_endpoint_is_int_in(endpoint))
-   goto descriptor_error;
-
/* We found a hub */
dev_info(>dev, "USB hub found\n");
 
@@ -1845,7 +1849,7 @@ static int hub_probe(struct usb_interface *intf, const 
struct usb_device_id *id)
if (id->driver_info & HUB_QUIRK_CHECK_PORT_AUTOSUSPEND)
hub->quirk_check_port_auto_suspend = 1;
 
-   if (hub_configure(hub, endpoint) >= 0)
+   if (hub_configure(hub, >endpoint[0].desc) >= 0)
return 0;
 
hub_disconnect(intf);
-- 
2.10.2


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