* [PATCH v5] USB hub_probe: rework ugly goto-into-compound-statement
@ 2016-11-13 12:53 Eugene Korenevsky
2016-11-14 6:49 ` Greg Kroah-Hartman
2016-11-14 6:50 ` Greg Kroah-Hartman
0 siblings, 2 replies; 4+ messages in thread
From: Eugene Korenevsky @ 2016-11-13 12:53 UTC (permalink / raw)
To: linux-kernel, linux-usb; +Cc: Greg Kroah-Hartman, Baolin Wang
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@gmail.com>
---
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 | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index cbb1467..1a316a1 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1722,10 +1722,25 @@ 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 it's not an interrupt in endpoint, we'd better punt! */
+ return usb_endpoint_is_int_in(&desc->endpoint[0].desc) != 0;
+}
+
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 +1815,11 @@ 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(&intf->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 = &desc->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(&intf->dev, "USB hub found\n");
@@ -1845,7 +1846,7 @@ 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, &desc->endpoint[0].desc) >= 0)
return 0;
hub_disconnect(intf);
--
2.10.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v5] USB hub_probe: rework ugly goto-into-compound-statement
2016-11-13 12:53 [PATCH v5] USB hub_probe: rework ugly goto-into-compound-statement Eugene Korenevsky
@ 2016-11-14 6:49 ` Greg Kroah-Hartman
2016-11-14 6:50 ` Greg Kroah-Hartman
1 sibling, 0 replies; 4+ messages in thread
From: Greg Kroah-Hartman @ 2016-11-14 6:49 UTC (permalink / raw)
To: Eugene Korenevsky, linux-kernel, linux-usb, Baolin Wang
On Sun, Nov 13, 2016 at 03:53:58PM +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@gmail.com>
> ---
> 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 | 35 ++++++++++++++++++-----------------
> 1 file changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index cbb1467..1a316a1 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -1722,10 +1722,25 @@ 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 it's not an interrupt in endpoint, we'd better punt! */
> + return usb_endpoint_is_int_in(&desc->endpoint[0].desc) != 0;
Ok, I'm going to be really pedantic here and ask that you spell this
last statement out:
if (usb...)
return true;
return false;
thanks,
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v5] USB hub_probe: rework ugly goto-into-compound-statement
2016-11-13 12:53 [PATCH v5] USB hub_probe: rework ugly goto-into-compound-statement Eugene Korenevsky
2016-11-14 6:49 ` Greg Kroah-Hartman
@ 2016-11-14 6:50 ` Greg Kroah-Hartman
2016-11-19 6:41 ` Eugene Korenevsky
1 sibling, 1 reply; 4+ messages in thread
From: Greg Kroah-Hartman @ 2016-11-14 6:50 UTC (permalink / raw)
To: Eugene Korenevsky, linux-kernel, linux-usb, Baolin Wang
On Sun, Nov 13, 2016 at 03:53:58PM +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@gmail.com>
> ---
> 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 | 35 ++++++++++++++++++-----------------
> 1 file changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index cbb1467..1a316a1 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -1722,10 +1722,25 @@ 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 it's not an interrupt in endpoint, we'd better punt! */
> + return usb_endpoint_is_int_in(&desc->endpoint[0].desc) != 0;
Also, the comment should say:
/* If the first endpoint is not interrupt IN, we... */
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v5] USB hub_probe: rework ugly goto-into-compound-statement
2016-11-14 6:50 ` Greg Kroah-Hartman
@ 2016-11-19 6:41 ` Eugene Korenevsky
0 siblings, 0 replies; 4+ messages in thread
From: Eugene Korenevsky @ 2016-11-19 6:41 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: linux-kernel, linux-usb
> Ok, I'm going to be really pedantic here and ask that you spell this
> last statement out:
> if (usb...)
> return true;
> return false;
>
> Also, the comment should say:
> /* If the first endpoint is not interrupt IN, we... */
>
It's better to inverse the condition and return false:
```
if (!usb...)
return false;
return true;
```
This is exactly what is said in the comment ("If the first endpoint...
we'd better punt!"). And does not break the composition of the entire
function (all `if` bodies return false, last statement is `return
true`).
--
Eugene
^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-11-13 12:53 [PATCH v5] USB hub_probe: rework ugly goto-into-compound-statement Eugene Korenevsky
2016-11-14 6:49 ` Greg Kroah-Hartman
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2016-11-19 6:41 ` Eugene Korenevsky
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