Re: [PATCH v1 1/2] usb: gadget: udc: core: Invoke usb_gadget_connect only when started

On Wed, Apr 05, 2023 at 09:31:32AM +0000, Badhri Jagan Sridharan wrote:

usb_udc_connect_control does not check to see if the udc has already been started. This causes gadget->ops->pullup to be called through usb_gadget_connect when invoked from usb_udc_vbus_handler even before usb_gadget_udc_start is called. Guard this by checking for udc->started in usb_udc_connect_control before invoking usb_gadget_connect.

Guarding udc_connect_control, udc->started and udc->vbus with its own mutex as usb_udc_connect_control_locked can be simulataneously invoked from different code paths.

You have a full 72 columns, please use them all :)

Cc: stable@vger.kernel.org

Signed-off-by: Badhri Jagan Sridharan badhri@google.com Fixes: 628ef0d273a6 ("usb: udc: add usb_udc_vbus_handler")

No blank line after cc: stable, and put the fixes above your signed-off-by line please.

---

drivers/usb/gadget/udc/core.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index 3dcbba739db6..890f92cb6344 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -56,6 +56,8 @@ static LIST_HEAD(udc_list); /* Protects udc_list, udc->driver, driver->is_bound, and related calls */ static DEFINE_MUTEX(udc_lock); +/* Protects udc->vbus, udc-started and udc_connect_control_locked */ +static DEFINE_MUTEX(udc_connect_control_lock);

Why a global lock? Shouldn't this be a per-device lock?

/* ------------------------------------------------------------------------- */ /** @@ -1078,9 +1080,10 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state); /* ------------------------------------------------------------------------- */ -static void usb_udc_connect_control(struct usb_udc *udc) +/* Acquire udc_connect_control_lock before calling this function. */ +static void usb_udc_connect_control_locked(struct usb_udc *udc) {

• if (udc->vbus)

• if (udc->vbus && udc->started) usb_gadget_connect(udc->gadget); else usb_gadget_disconnect(udc->gadget);

@@ -1099,10 +1102,12 @@ void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status) { struct usb_udc *udc = gadget->udc;

• mutex_lock(&udc_connect_control_lock); if (udc) { udc->vbus = status;

• usb_udc_connect_control(udc);
  

• usb_udc_connect_control_locked(udc);
  

  }
• mutex_unlock(&udc_connect_control_lock);

} EXPORT_SYMBOL_GPL(usb_udc_vbus_handler); @@ -1140,14 +1145,18 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc) { int ret;

• mutex_lock(&udc_connect_control_lock); if (udc->started) { dev_err(&udc->dev, "UDC had already started\n");

• mutex_unlock(&udc_connect_control_lock);
  

  return -EBUSY; }

ret = udc->gadget->ops->udc_start(udc->gadget, udc->driver); if (!ret) udc->started = true;

• usb_udc_connect_control_locked(udc);
• mutex_unlock(&udc_connect_control_lock);

return ret; } @@ -1165,13 +1174,17 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc) */ static inline void usb_gadget_udc_stop(struct usb_udc *udc) {

• mutex_lock(&udc_connect_control_lock); if (!udc->started) { dev_err(&udc->dev, "UDC had already stopped\n");

• mutex_unlock(&udc_connect_control_lock);
  

  return; }

udc->gadget->ops->udc_stop(udc->gadget); udc->started = false;

• usb_udc_connect_control_locked(udc);
• mutex_unlock(&udc_connect_control_lock);

} /** @@ -1527,7 +1540,6 @@ static int gadget_bind_driver(struct device *dev) if (ret) goto err_start; usb_gadget_enable_async_callbacks(udc);

• usb_udc_connect_control(udc);

Why drop this call here?

thanks,

greg k-h