On Wed, Sep 27, 2023 at 01:07:08AM +0530, Krishna Kurapati wrote:
> In the event, gadget_connect call (which invokes pullup) fails,
s/event,/event/
> propagate the error to udc bind operation which inturn sends the
s/inturn/in turn/
> error to configfs. The userspace can then retry enumeartion if
s/enumeartion/enumeration/
> it chooses to.
>
> Signed-off-by: Krishna Kurapati <[email protected]>
> ---
> Changes in v4: Fixed mutex locking imbalance during connect_control
> failure
> Link to v3: https://lore.kernel.org/all/[email protected]/
>
> drivers/usb/gadget/udc/core.c | 23 +++++++++++++++++++----
> 1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 7d49d8a0b00c..53af25a333a1 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1125,12 +1125,16 @@ 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)
> {
> + int ret;
> +
> if (udc->vbus)
> - usb_gadget_connect_locked(udc->gadget);
> + ret = usb_gadget_connect_locked(udc->gadget);
> else
> - usb_gadget_disconnect_locked(udc->gadget);
> + ret = usb_gadget_disconnect_locked(udc->gadget);
> +
> + return ret;
You don't actually need the new variable ret. You can just do:
if (udc->vbus)
return usb_gadget_connect_locked(udc->gadget);
else
return usb_gadget_disconnect_locked(udc->gadget);
> }
>
> static void vbus_event_work(struct work_struct *work)
> @@ -1604,12 +1608,23 @@ 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) {
> + mutex_unlock(&udc->connect_lock);
> + goto err_connect_control;
> + }
> +
> mutex_unlock(&udc->connect_lock);
>
> kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
> return 0;
>
> + err_connect_control:
> + usb_gadget_disable_async_callbacks(udc);
> + if (gadget->irq)
> + synchronize_irq(gadget->irq);
> + usb_gadget_udc_stop_locked(udc);
Not good -- usb_gadget_udc_stop_locked() expects you to be holding
udc->connect_lock, but you just dropped the lock! Also, you never set
udc->allow_connect back to false.
You should move the mutex_unlock() call from inside the "if" statement
to down here, and add a line for udc->allow_connect.
Alan Stern
> +
> err_start:
> driver->unbind(udc->gadget);
>
> --
> 2.42.0
>
On 9/27/2023 1:24 AM, Alan Stern wrote:
> On Wed, Sep 27, 2023 at 01:07:08AM +0530, Krishna Kurapati wrote:
>> In the event, gadget_connect call (which invokes pullup) fails,
>
> s/event,/event/
>
>> propagate the error to udc bind operation which inturn sends the
>
> s/inturn/in turn/
>
>> error to configfs. The userspace can then retry enumeartion if
>
> s/enumeartion/enumeration/
>
>> it chooses to.
>>
>> Signed-off-by: Krishna Kurapati <[email protected]>
>> ---
>> Changes in v4: Fixed mutex locking imbalance during connect_control
>> failure
>> Link to v3: https://lore.kernel.org/all/[email protected]/
>>
>> drivers/usb/gadget/udc/core.c | 23 +++++++++++++++++++----
>> 1 file changed, 19 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
>> index 7d49d8a0b00c..53af25a333a1 100644
>> --- a/drivers/usb/gadget/udc/core.c
>> +++ b/drivers/usb/gadget/udc/core.c
>> @@ -1125,12 +1125,16 @@ 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)
>> {
>> + int ret;
>> +
>> if (udc->vbus)
>> - usb_gadget_connect_locked(udc->gadget);
>> + ret = usb_gadget_connect_locked(udc->gadget);
>> else
>> - usb_gadget_disconnect_locked(udc->gadget);
>> + ret = usb_gadget_disconnect_locked(udc->gadget);
>> +
>> + return ret;
>
> You don't actually need the new variable ret. You can just do:
>
> if (udc->vbus)
> return usb_gadget_connect_locked(udc->gadget);
> else
> return usb_gadget_disconnect_locked(udc->gadget);
>
>> }
>>
>> static void vbus_event_work(struct work_struct *work)
>> @@ -1604,12 +1608,23 @@ 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) {
>> + mutex_unlock(&udc->connect_lock);
>> + goto err_connect_control;
>> + }
>> +
>> mutex_unlock(&udc->connect_lock);
>>
>> kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
>> return 0;
>>
>> + err_connect_control:
>> + usb_gadget_disable_async_callbacks(udc);
>> + if (gadget->irq)
>> + synchronize_irq(gadget->irq);
>> + usb_gadget_udc_stop_locked(udc);
>
> Not good -- usb_gadget_udc_stop_locked() expects you to be holding
> udc->connect_lock, but you just dropped the lock! Also, you never set
> udc->allow_connect back to false.
>
> You should move the mutex_unlock() call from inside the "if" statement
> to down here, and add a line for udc->allow_connect.
>
Hi Alan,
Thanks for the review. Will push v5 addressing the changes.
Regards,
Krishna,