[PATCH v2 2/2] usb: dwc3: fix race of usb_gadget_driver operation

[Linyu Yuan]

there is following race condition,

      CPU1                         CPU2
dwc3_runtime_suspend()        dwc3_gadget_stop()
spin_lock(&dwc->lock)
dwc3_gadget_suspend()
dwc3_disconnect_gadget()
dwc->gadget_driver != NULL
spin_unlock(&dwc->lock)
                              spin_lock(&dwc->lock)
                              dwc->gadget_driver = NULL
                              spin_unlock(&dwc->lock)
dwc->gadget_driver->disconnect(dwc->gadget);

system will crash when access NULL pointer.

this change will remove pointer of upper layer
struct usb_gadget_driver,
use UDC safe api to access necessary function.

Signed-off-by: Linyu Yuan <linyyuan@xxxxxxxxxxxxxx>
---
 drivers/usb/dwc3/core.h   |  2 --
 drivers/usb/dwc3/ep0.c    |  6 +----
 drivers/usb/dwc3/gadget.c | 53 ++++++++++-----------------------------
 3 files changed, 14 insertions(+), 47 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index dccdf13b5f9e..4db64d103446 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -962,7 +962,6 @@ struct dwc3_scratchpad_array {
  * @ev_buf: struct dwc3_event_buffer pointer
  * @eps: endpoint array
  * @gadget: device side representation of the peripheral controller
- * @gadget_driver: pointer to the gadget driver
  * @clks: array of clocks
  * @num_clks: number of clocks
  * @reset: reset control
@@ -1108,7 +1107,6 @@ struct dwc3 {
 	struct dwc3_ep		*eps[DWC3_ENDPOINTS_NUM];
 
 	struct usb_gadget	*gadget;
-	struct usb_gadget_driver *gadget_driver;
 
 	struct clk_bulk_data	*clks;
 	int			num_clks;
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 3cd294264372..89f63be00902 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -600,7 +600,7 @@ static int dwc3_ep0_delegate_req(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 	int ret;
 
 	spin_unlock(&dwc->lock);
-	ret = dwc->gadget_driver->setup(dwc->gadget, ctrl);
+	ret = usb_gadget_udc_setup(dwc->gadget, ctrl);
 	spin_lock(&dwc->lock);
 	return ret;
 }
@@ -795,9 +795,6 @@ static void dwc3_ep0_inspect_setup(struct dwc3 *dwc,
 	int ret = -EINVAL;
 	u32 len;
 
-	if (!dwc->gadget_driver)
-		goto out;
-
 	trace_dwc3_ctrl_req(ctrl);
 
 	len = le16_to_cpu(ctrl->wLength);
@@ -819,7 +816,6 @@ static void dwc3_ep0_inspect_setup(struct dwc3 *dwc,
 	if (ret == USB_GADGET_DELAYED_STATUS)
 		dwc->delayed_status = true;
 
-out:
 	if (ret < 0)
 		dwc3_ep0_stall_and_restart(dwc);
 }
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index af6d7f157989..8cb7a9826ee1 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2464,7 +2464,6 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 		struct usb_gadget_driver *driver)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
-	unsigned long		flags;
 	int			ret;
 	int			irq;
 
@@ -2477,10 +2476,6 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 		return ret;
 	}
 
-	spin_lock_irqsave(&dwc->lock, flags);
-	dwc->gadget_driver	= driver;
-	spin_unlock_irqrestore(&dwc->lock, flags);
-
 	return 0;
 }
 
@@ -2494,11 +2489,6 @@ static void __dwc3_gadget_stop(struct dwc3 *dwc)
 static int dwc3_gadget_stop(struct usb_gadget *g)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
-	unsigned long		flags;
-
-	spin_lock_irqsave(&dwc->lock, flags);
-	dwc->gadget_driver	= NULL;
-	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	free_irq(dwc->irq_gadget, dwc->ev_buf);
 
@@ -3231,39 +3221,30 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 
 static void dwc3_disconnect_gadget(struct dwc3 *dwc)
 {
-	if (dwc->gadget_driver && dwc->gadget_driver->disconnect) {
-		spin_unlock(&dwc->lock);
-		dwc->gadget_driver->disconnect(dwc->gadget);
-		spin_lock(&dwc->lock);
-	}
+	spin_unlock(&dwc->lock);
+	usb_gadget_udc_disconnect(dwc->gadget);
+	spin_lock(&dwc->lock);
 }
 
 static void dwc3_suspend_gadget(struct dwc3 *dwc)
 {
-	if (dwc->gadget_driver && dwc->gadget_driver->suspend) {
-		spin_unlock(&dwc->lock);
-		dwc->gadget_driver->suspend(dwc->gadget);
-		spin_lock(&dwc->lock);
-	}
+	spin_unlock(&dwc->lock);
+	usb_gadget_udc_suspend(dwc->gadget);
+	spin_lock(&dwc->lock);
 }
 
 static void dwc3_resume_gadget(struct dwc3 *dwc)
 {
-	if (dwc->gadget_driver && dwc->gadget_driver->resume) {
-		spin_unlock(&dwc->lock);
-		dwc->gadget_driver->resume(dwc->gadget);
-		spin_lock(&dwc->lock);
-	}
+	spin_unlock(&dwc->lock);
+	usb_gadget_udc_resume(dwc->gadget);
+	spin_lock(&dwc->lock);
 }
 
 static void dwc3_reset_gadget(struct dwc3 *dwc)
 {
-	if (!dwc->gadget_driver)
-		return;
-
 	if (dwc->gadget->speed != USB_SPEED_UNKNOWN) {
 		spin_unlock(&dwc->lock);
-		usb_gadget_udc_reset(dwc->gadget, dwc->gadget_driver);
+		usb_gadget_udc_reset(dwc->gadget, NULL);
 		spin_lock(&dwc->lock);
 	}
 }
@@ -3585,11 +3566,9 @@ static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
 	 * implemented.
 	 */
 
-	if (dwc->gadget_driver && dwc->gadget_driver->resume) {
-		spin_unlock(&dwc->lock);
-		dwc->gadget_driver->resume(dwc->gadget);
-		spin_lock(&dwc->lock);
-	}
+	spin_unlock(&dwc->lock);
+	usb_gadget_udc_resume(dwc->gadget);
+	spin_lock(&dwc->lock);
 }
 
 static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
@@ -4085,9 +4064,6 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
 
 int dwc3_gadget_suspend(struct dwc3 *dwc)
 {
-	if (!dwc->gadget_driver)
-		return 0;
-
 	dwc3_gadget_run_stop(dwc, false, false);
 	dwc3_disconnect_gadget(dwc);
 	__dwc3_gadget_stop(dwc);
@@ -4099,9 +4075,6 @@ int dwc3_gadget_resume(struct dwc3 *dwc)
 {
 	int			ret;
 
-	if (!dwc->gadget_driver)
-		return 0;
-
 	ret = __dwc3_gadget_start(dwc);
 	if (ret < 0)
 		goto err0;
-- 
2.25.1