[v5] usb: gadget: udc: Handle gadget_connect failure during bind operation

[PATCH v5] usb: gadget: udc: Handle gadget_connect failure during bind operation

Posted by Krishna Kurapati 2 years, 4 months ago

In the event gadget_connect call (which invokes pullup) fails,
propagate the error to udc bind operation which in turn sends the
error to configfs. The userspace can then retry enumeration if
it chooses to.

Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
---
Changes in v5: Addressed proper unlocking of control_lock mutex

 drivers/usb/gadget/udc/core.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 7d49d8a0b00c..824fe64e078a 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1125,12 +1125,12 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
 /* ------------------------------------------------------------------------- */
 
 /* Acquire connect_lock before calling this function. */
-static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
+static int usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
 {
 	if (udc->vbus)
-		usb_gadget_connect_locked(udc->gadget);
+		return usb_gadget_connect_locked(udc->gadget);
 	else
-		usb_gadget_disconnect_locked(udc->gadget);
+		return usb_gadget_disconnect_locked(udc->gadget);
 }
 
 static void vbus_event_work(struct work_struct *work)
@@ -1604,12 +1604,23 @@ static int gadget_bind_driver(struct device *dev)
 	}
 	usb_gadget_enable_async_callbacks(udc);
 	udc->allow_connect = true;
-	usb_udc_connect_control_locked(udc);
+	ret = usb_udc_connect_control_locked(udc);
+	if (ret)
+		goto err_connect_control;
+
 	mutex_unlock(&udc->connect_lock);
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 	return 0;
 
+ err_connect_control:
+	udc->allow_connect = false;
+	usb_gadget_disable_async_callbacks(udc);
+	if (gadget->irq)
+		synchronize_irq(gadget->irq);
+	usb_gadget_udc_stop_locked(udc);
+	mutex_unlock(&udc->connect_lock);
+
  err_start:
 	driver->unbind(udc->gadget);
 
-- 
2.42.0

Re: [PATCH v5] usb: gadget: udc: Handle gadget_connect failure during bind operation

Posted by Alan Stern 2 years, 4 months ago

On Wed, Sep 27, 2023 at 01:00:27PM +0530, Krishna Kurapati wrote:
> In the event gadget_connect call (which invokes pullup) fails,
> propagate the error to udc bind operation which in turn sends the
> error to configfs. The userspace can then retry enumeration if
> it chooses to.
> 
> Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
> ---
> Changes in v5: Addressed proper unlocking of control_lock mutex

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

>  drivers/usb/gadget/udc/core.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 7d49d8a0b00c..824fe64e078a 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1125,12 +1125,12 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
>  /* ------------------------------------------------------------------------- */
>  
>  /* Acquire connect_lock before calling this function. */
> -static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
> +static int usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
>  {
>  	if (udc->vbus)
> -		usb_gadget_connect_locked(udc->gadget);
> +		return usb_gadget_connect_locked(udc->gadget);
>  	else
> -		usb_gadget_disconnect_locked(udc->gadget);
> +		return usb_gadget_disconnect_locked(udc->gadget);
>  }
>  
>  static void vbus_event_work(struct work_struct *work)
> @@ -1604,12 +1604,23 @@ static int gadget_bind_driver(struct device *dev)
>  	}
>  	usb_gadget_enable_async_callbacks(udc);
>  	udc->allow_connect = true;
> -	usb_udc_connect_control_locked(udc);
> +	ret = usb_udc_connect_control_locked(udc);
> +	if (ret)
> +		goto err_connect_control;
> +
>  	mutex_unlock(&udc->connect_lock);
>  
>  	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
>  	return 0;
>  
> + err_connect_control:
> +	udc->allow_connect = false;
> +	usb_gadget_disable_async_callbacks(udc);
> +	if (gadget->irq)
> +		synchronize_irq(gadget->irq);
> +	usb_gadget_udc_stop_locked(udc);
> +	mutex_unlock(&udc->connect_lock);
> +
>   err_start:
>  	driver->unbind(udc->gadget);
>  
> -- 
> 2.42.0
>

Re: [PATCH v5] usb: gadget: udc: Handle gadget_connect failure during bind operation

Posted by Greg Kroah-Hartman 2 years, 4 months ago

On Wed, Sep 27, 2023 at 01:00:27PM +0530, Krishna Kurapati wrote:
> In the event gadget_connect call (which invokes pullup) fails,
> propagate the error to udc bind operation which in turn sends the
> error to configfs. The userspace can then retry enumeration if
> it chooses to.

Will this break userspace that is not expecting error codes to be
returned?  What userspace code will now be modified to handle this?
Where is that work happening?

thanks,

greg k-h