[PATCH v2] USB: gadget: core: adjust uevent timing on gadget unbind

[PATCH v2] USB: gadget: core: adjust uevent timing on gadget unbind

[Roy Luo]

The KOBJ_CHANGE uevent is sent before gadget unbind is actually
executed, resulting in inaccurate uevent emitted at incorrect timing
(the uevent would have USB_UDC_DRIVER variable set while it would
soon be removed).
Move the KOBJ_CHANGE uevent to the end of the unbind function so that
uevent is sent only after the change has been made.

Fixes: 2ccea03a8f7e ("usb: gadget: introduce UDC Class")
Signed-off-by: Roy Luo <royluo@google.com>
---
Changes since v1: add Fixes tag
---
 drivers/usb/gadget/udc/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index ded9531f141b..d59f94464b87 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1646,8 +1646,6 @@ static void gadget_unbind_driver(struct device *dev)
 
 	dev_dbg(&udc->dev, "unbinding gadget driver [%s]\n", driver->function);
 
-	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
-
 	udc->allow_connect = false;
 	cancel_work_sync(&udc->vbus_work);
 	mutex_lock(&udc->connect_lock);
@@ -1667,6 +1665,8 @@ static void gadget_unbind_driver(struct device *dev)
 	driver->is_bound = false;
 	udc->driver = NULL;
 	mutex_unlock(&udc_lock);
+
+	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 }
 
 /* ------------------------------------------------------------------------- */

base-commit: 9b6de136b5f0158c60844f85286a593cb70fb364
-- 
2.43.0.rc1.413.gea7ed67945-goog

Re: [PATCH v2] USB: gadget: core: adjust uevent timing on gadget unbind

[Greg KH]

On Mon, Nov 27, 2023 at 10:00:47PM +0000, Roy Luo wrote:
> The KOBJ_CHANGE uevent is sent before gadget unbind is actually
> executed, resulting in inaccurate uevent emitted at incorrect timing
> (the uevent would have USB_UDC_DRIVER variable set while it would
> soon be removed).
> Move the KOBJ_CHANGE uevent to the end of the unbind function so that
> uevent is sent only after the change has been made.
> 
> Fixes: 2ccea03a8f7e ("usb: gadget: introduce UDC Class")
> Signed-off-by: Roy Luo <royluo@google.com>
> ---
> Changes since v1: add Fixes tag
> ---
>  drivers/usb/gadget/udc/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH v2] USB: gadget: core: adjust uevent timing on gadget unbind

[Roy Luo]

On Tue, Nov 28, 2023 at 12:00 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> - You have marked a patch with a "Fixes:" tag for a commit that is in an
>   older released kernel, yet you do not have a cc: stable line in the
>   signed-off-by area at all, which means that the patch will not be
>   applied to any older kernel releases.  To properly fix this, please
>   follow the documented rules in the
>   Documentation/process/stable-kernel-rules.rst file for how to resolve
>   this.

I don't see a need for this patch to go into stable kernels after
reviewing Documentation/process/stable-kernel-rules.rst, please let me
know if you think otherwise.

Thanks,
Roy

Re: [PATCH v2] USB: gadget: core: adjust uevent timing on gadget unbind

[Greg KH]

On Tue, Nov 28, 2023 at 10:52:49AM -0800, Roy Luo wrote:
> On Tue, Nov 28, 2023 at 12:00 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > - You have marked a patch with a "Fixes:" tag for a commit that is in an
> >   older released kernel, yet you do not have a cc: stable line in the
> >   signed-off-by area at all, which means that the patch will not be
> >   applied to any older kernel releases.  To properly fix this, please
> >   follow the documented rules in the
> >   Documentation/process/stable-kernel-rules.rst file for how to resolve
> >   this.
> 
> I don't see a need for this patch to go into stable kernels after
> reviewing Documentation/process/stable-kernel-rules.rst, please let me
> know if you think otherwise.

If you think this fixes a bug in the existing code, why wouldn't it be
needed?

Also, this implies that you will not be wanting it backported to any
chromeos or android kernels?

thanks,

greg k-h

Re: [PATCH v2] USB: gadget: core: adjust uevent timing on gadget unbind

[Roy Luo]

On Tue, Nov 28, 2023 at 11:01 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> If you think this fixes a bug in the existing code, why wouldn't it be
> needed?
>
> Also, this implies that you will not be wanting it backported to any
> chromeos or android kernels?

Maybe I didn't get the criterias in
Documentation/process/stable-kernel-rules.rst right, and yes, I do
want to backport it to android kernels.
Anyway, I'm sending a new patch with Cc: stable@vger.kernel.org

Thanks,
Roy