[PATCH] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[PATCH] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Michal Nazarewicz]

From: Michal Nazarewicz <mina86@mina86.com>

The usb_create_sysfs_intf_files() function always returned zero even
if it failed to create sysfs fails.  Since this is a desired behaviour
there is no need to return return code at all.  This commit changes
function's return type (form int) to void.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/usb/core/sysfs.c |    7 +++----
 drivers/usb/core/usb.c   |    3 +--
 drivers/usb/core/usb.h   |    2 +-
 3 files changed, 5 insertions(+), 7 deletions(-)

The below patch has not been tested (not even compiled), just a quick scatch.

> On Thu, 24 Mar 2011, Sergey Senozhatsky wrote:
>> I just noticed that usb_create_sysfs_intf_files() ignores  
>> device_create_file() return code and sets intf->sysfs_files_created
>> to 1, even if sysfs_add_file_mode() returned -ENOMEM (or later
>> sysfs_add_one() returned -EEXIST).
>>
>> Shouldn't we check retval for 0 before setting  
>> intf->sysfs_files_created?

On Thu, 24 Mar 2011 15:55:08 +0100, Alan Stern <stern@rowland.harvard.edu> wrote:
> No.  We want this routine to succeed even if the sysfs files can't be
> created.  The interface string attribute is more or less optional.
>
> It would be okay to add a comment explaining this, so that other people
> don't make the same mistake (which has already happened -- you're not
> the first).

Can we also drop the return value completely then?


diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 6781c36..e729480 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -842,11 +842,10 @@ const struct attribute_group *usb_interface_groups[] = {
 	NULL
 };
 
-int usb_create_sysfs_intf_files(struct usb_interface *intf)
+void usb_create_sysfs_intf_files(struct usb_interface *intf)
 {
 	struct usb_device *udev = interface_to_usbdev(intf);
 	struct usb_host_interface *alt = intf->cur_altsetting;
-	int retval;
 
 	if (intf->sysfs_files_created || intf->unregistering)
 		return 0;
@@ -855,9 +854,9 @@ int usb_create_sysfs_intf_files(struct usb_interface *intf)
 			!(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
 		alt->string = usb_cache_string(udev, alt->desc.iInterface);
 	if (alt->string)
-		retval = device_create_file(&intf->dev, &dev_attr_interface);
+		/* We don't care if the function actually fails. */
+		device_create_file(&intf->dev, &dev_attr_interface);
 	intf->sysfs_files_created = 1;
-	return 0;
 }
 
 void usb_remove_sysfs_intf_files(struct usb_interface *intf)
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 079cb57..08b74f8 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -948,8 +948,7 @@ static int usb_bus_notify(struct notifier_block *nb, unsigned long action,
 		if (dev->type == &usb_device_type)
 			(void) usb_create_sysfs_dev_files(to_usb_device(dev));
 		else if (dev->type == &usb_if_device_type)
-			(void) usb_create_sysfs_intf_files(
-					to_usb_interface(dev));
+			usb_create_sysfs_intf_files(to_usb_interface(dev));
 		break;
 
 	case BUS_NOTIFY_DEL_DEVICE:
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index a9cf484..d51ab6a 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -4,7 +4,7 @@
 
 extern int usb_create_sysfs_dev_files(struct usb_device *dev);
 extern void usb_remove_sysfs_dev_files(struct usb_device *dev);
-extern int usb_create_sysfs_intf_files(struct usb_interface *intf);
+extern void usb_create_sysfs_intf_files(struct usb_interface *intf);
 extern void usb_remove_sysfs_intf_files(struct usb_interface *intf);
 extern int usb_create_ep_devs(struct device *parent,
 				struct usb_host_endpoint *endpoint,
-- 
1.7.3.1

Re: [PATCH] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Alan Stern]

On Thu, 24 Mar 2011, Michal Nazarewicz wrote:

> From: Michal Nazarewicz <mina86@mina86.com>
> 
> The usb_create_sysfs_intf_files() function always returned zero even
> if it failed to create sysfs fails.  Since this is a desired behaviour
> there is no need to return return code at all.  This commit changes
> function's return type (form int) to void.
> 
> Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> ---
>  drivers/usb/core/sysfs.c |    7 +++----
>  drivers/usb/core/usb.c   |    3 +--
>  drivers/usb/core/usb.h   |    2 +-
>  3 files changed, 5 insertions(+), 7 deletions(-)
> 
> The below patch has not been tested (not even compiled), just a quick scatch.

If you had compiled it, you would have seen why it's not a good idea to 
remove retval.  :-)

On the other hand, changing the function's return type to void is okay.  
I think the reason it returns int is historical; there used to be a
failure mode but it got removed.

Alan Stern

Re: [PATCH] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Michal Nazarewicz]

> On Thu, 24 Mar 2011, Michal Nazarewicz wrote:
>> The usb_create_sysfs_intf_files() function always returned zero even
>> if it failed to create sysfs fails.  Since this is a desired behaviour
>> there is no need to return return code at all.  This commit changes
>> function's return type (form int) to void.
[...]
>> The below patch has not been tested (not even compiled), just a quick  
>> scatch.

On Thu, 24 Mar 2011 16:52:36 +0100, Alan Stern wrote:
> If you had compiled it, you would have seen why it's not a good idea to
> remove retval.  :-)

I must be getting blind...  I explicitly checked if device_create_file()
has __must_check attribute but somehow missed it.

> On the other hand, changing the function's return type to void is okay.
> I think the reason it returns int is historical; there used to be a
> failure mode but it got removed.

In that case I can prepare a v2 later today (unless Sergey feels like
doing that).

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michal "mina86" Nazarewicz    (o o)
ooo +-----<email/xmpp: mnazarewicz@google.com>-----ooO--(_)--Ooo--

[PATCHv2] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Michal Nazarewicz]

From: Michal Nazarewicz <mina86@mina86.com>

The usb_create_sysfs_intf_files() function always returned zero even
if it failed to create sysfs fails.  Since this is a desired behaviour
there is no need to return return code at all.  This commit changes
function's return type (form int) to void.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/usb/core/sysfs.c |   13 +++++--------
 drivers/usb/core/usb.c   |    3 +--
 drivers/usb/core/usb.h   |    2 +-
 3 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 6781c36..f5b7b1c 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -842,22 +842,19 @@ const struct attribute_group *usb_interface_groups[] = {
 	NULL
 };
 
-int usb_create_sysfs_intf_files(struct usb_interface *intf)
+void usb_create_sysfs_intf_files(struct usb_interface *intf)
 {
 	struct usb_device *udev = interface_to_usbdev(intf);
 	struct usb_host_interface *alt = intf->cur_altsetting;
-	int retval;
 
 	if (intf->sysfs_files_created || intf->unregistering)
-		return 0;
+		return;
 
-	if (alt->string == NULL &&
-			!(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
+	if (!alt->string && !(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
 		alt->string = usb_cache_string(udev, alt->desc.iInterface);
-	if (alt->string)
-		retval = device_create_file(&intf->dev, &dev_attr_interface);
+	if (alt->string && device_create_file(&intf->dev, &dev_attr_interface))
+		/* We don't actually care if the function fails. */;
 	intf->sysfs_files_created = 1;
-	return 0;
 }
 
 void usb_remove_sysfs_intf_files(struct usb_interface *intf)
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 079cb57..08b74f8 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -948,8 +948,7 @@ static int usb_bus_notify(struct notifier_block *nb, unsigned long action,
 		if (dev->type == &usb_device_type)
 			(void) usb_create_sysfs_dev_files(to_usb_device(dev));
 		else if (dev->type == &usb_if_device_type)
-			(void) usb_create_sysfs_intf_files(
-					to_usb_interface(dev));
+			usb_create_sysfs_intf_files(to_usb_interface(dev));
 		break;
 
 	case BUS_NOTIFY_DEL_DEVICE:
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index a9cf484..d51ab6a 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -4,7 +4,7 @@
 
 extern int usb_create_sysfs_dev_files(struct usb_device *dev);
 extern void usb_remove_sysfs_dev_files(struct usb_device *dev);
-extern int usb_create_sysfs_intf_files(struct usb_interface *intf);
+extern void usb_create_sysfs_intf_files(struct usb_interface *intf);
 extern void usb_remove_sysfs_intf_files(struct usb_interface *intf);
 extern int usb_create_ep_devs(struct device *parent,
 				struct usb_host_endpoint *endpoint,
-- 
1.7.3.1

Re: [PATCHv2] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Alan Stern]

On Fri, 25 Mar 2011, Michal Nazarewicz wrote:

> From: Michal Nazarewicz <mina86@mina86.com>
> 
> The usb_create_sysfs_intf_files() function always returned zero even
> if it failed to create sysfs fails.  Since this is a desired behaviour
> there is no need to return return code at all.  This commit changes
> function's return type (form int) to void.
> 
> Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> ---
>  drivers/usb/core/sysfs.c |   13 +++++--------
>  drivers/usb/core/usb.c   |    3 +--
>  drivers/usb/core/usb.h   |    2 +-
>  3 files changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
> index 6781c36..f5b7b1c 100644
> --- a/drivers/usb/core/sysfs.c
> +++ b/drivers/usb/core/sysfs.c
> @@ -842,22 +842,19 @@ const struct attribute_group *usb_interface_groups[] = {
>  	NULL
>  };
>  
> -int usb_create_sysfs_intf_files(struct usb_interface *intf)
> +void usb_create_sysfs_intf_files(struct usb_interface *intf)
>  {
>  	struct usb_device *udev = interface_to_usbdev(intf);
>  	struct usb_host_interface *alt = intf->cur_altsetting;
> -	int retval;
>  
>  	if (intf->sysfs_files_created || intf->unregistering)
> -		return 0;
> +		return;
>  
> -	if (alt->string == NULL &&
> -			!(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
> +	if (!alt->string && !(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
>  		alt->string = usb_cache_string(udev, alt->desc.iInterface);
> -	if (alt->string)
> -		retval = device_create_file(&intf->dev, &dev_attr_interface);
> +	if (alt->string && device_create_file(&intf->dev, &dev_attr_interface))
> +		/* We don't actually care if the function fails. */;

My style preference is to put the empty statement before the comment.  
It's unusual to have a comment appearing before a statement on the same
line.  For example:

		;	/* We don't care if the function fails */

Alan Stern

Re: [PATCHv3] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Alan Stern]

On Fri, 25 Mar 2011, Michal Nazarewicz wrote:

> The usb_create_sysfs_intf_files() function always returned zero even
> if it failed to create sysfs fails.  Since this is a desired behaviour
> there is no need to return return code at all.  This commit changes
> function's return type (form int) to void.
> 
> Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> ---
>  drivers/usb/core/sysfs.c |   13 +++++--------
>  drivers/usb/core/usb.c   |    3 +--
>  drivers/usb/core/usb.h   |    2 +-
>  3 files changed, 7 insertions(+), 11 deletions(-)
> 
> On Fri, 25 Mar 2011 16:33:12 +0100, Alan Stern <stern@rowland.harvard.edu> wrote:
> > My style preference is to put the empty statement before the comment.
> > It's unusual to have a comment appearing before a statement on the same
> > line.  For example:
> >		;	/* We don't care if the function fails */
> 
> Changed.  And I agree, it looks better now. :)

Acked-by: Alan Stern <stern@rowland.harvard.edu>

Re: [PATCHv3] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Greg KH]

On Fri, Mar 25, 2011 at 01:03:12PM -0400, Alan Stern wrote:
> On Fri, 25 Mar 2011, Michal Nazarewicz wrote:
> 
> > The usb_create_sysfs_intf_files() function always returned zero even
> > if it failed to create sysfs fails.  Since this is a desired behaviour
> > there is no need to return return code at all.  This commit changes
> > function's return type (form int) to void.
> > 
> > Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
> > Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> > ---
> >  drivers/usb/core/sysfs.c |   13 +++++--------
> >  drivers/usb/core/usb.c   |    3 +--
> >  drivers/usb/core/usb.h   |    2 +-
> >  3 files changed, 7 insertions(+), 11 deletions(-)
> > 
> > On Fri, 25 Mar 2011 16:33:12 +0100, Alan Stern <stern@rowland.harvard.edu> wrote:
> > > My style preference is to put the empty statement before the comment.
> > > It's unusual to have a comment appearing before a statement on the same
> > > line.  For example:
> > >		;	/* We don't care if the function fails */
> > 
> > Changed.  And I agree, it looks better now. :)
> 
> Acked-by: Alan Stern <stern@rowland.harvard.edu>

I can't find this version of the patch in my email archive anywhere.

Michal, can you resend it so I can apply it?

thanks,

greg k-h

[PATCHv3] usb: core: Change usb_create_sysfs_intf_files()' return type to void

[Michal Nazarewicz]

The usb_create_sysfs_intf_files() function always returned zero even
if it failed to create sysfs fails.  Since this is a desired behaviour
there is no need to return return code at all.  This commit changes
function's return type (form int) to void.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/usb/core/sysfs.c |   13 +++++--------
 drivers/usb/core/usb.c   |    3 +--
 drivers/usb/core/usb.h   |    2 +-
 3 files changed, 7 insertions(+), 11 deletions(-)


On Thu, 14 Apr 2011 01:23:15 +0200, Greg KH <greg@kroah.com> wrote:
> I can't find this version of the patch in my email archive anywhere.
>
> Michal, can you resend it so I can apply it?

Here it is.


diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 6781c36..cf05b97 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -842,22 +842,19 @@ const struct attribute_group *usb_interface_groups[] = {
 	NULL
 };
 
-int usb_create_sysfs_intf_files(struct usb_interface *intf)
+void usb_create_sysfs_intf_files(struct usb_interface *intf)
 {
 	struct usb_device *udev = interface_to_usbdev(intf);
 	struct usb_host_interface *alt = intf->cur_altsetting;
-	int retval;
 
 	if (intf->sysfs_files_created || intf->unregistering)
-		return 0;
+		return;
 
-	if (alt->string == NULL &&
-			!(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
+	if (!alt->string && !(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
 		alt->string = usb_cache_string(udev, alt->desc.iInterface);
-	if (alt->string)
-		retval = device_create_file(&intf->dev, &dev_attr_interface);
+	if (alt->string && device_create_file(&intf->dev, &dev_attr_interface))
+		;	/* We don't actually care if the function fails. */
 	intf->sysfs_files_created = 1;
-	return 0;
 }
 
 void usb_remove_sysfs_intf_files(struct usb_interface *intf)
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index d9d4b16..8706fc9 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -953,8 +953,7 @@ static int usb_bus_notify(struct notifier_block *nb, unsigned long action,
 		if (dev->type == &usb_device_type)
 			(void) usb_create_sysfs_dev_files(to_usb_device(dev));
 		else if (dev->type == &usb_if_device_type)
-			(void) usb_create_sysfs_intf_files(
-					to_usb_interface(dev));
+			usb_create_sysfs_intf_files(to_usb_interface(dev));
 		break;
 
 	case BUS_NOTIFY_DEL_DEVICE:
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index d450b74..d44d4b7 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -4,7 +4,7 @@
 
 extern int usb_create_sysfs_dev_files(struct usb_device *dev);
 extern void usb_remove_sysfs_dev_files(struct usb_device *dev);
-extern int usb_create_sysfs_intf_files(struct usb_interface *intf);
+extern void usb_create_sysfs_intf_files(struct usb_interface *intf);
 extern void usb_remove_sysfs_intf_files(struct usb_interface *intf);
 extern int usb_create_ep_devs(struct device *parent,
 				struct usb_host_endpoint *endpoint,
-- 
1.7.3.1