usb: dwc3: Properly handle processing of pending events

If dwc3 is runtime suspended we defer processing the event buffer
until resume, by setting the pending_events flag. Set this flag before
triggering resume to avoid race with the runtime resume callback.

While handling the pending events, in addition to checking the event
buffer we also need to process it. Handle this by explicitly calling
dwc3_thread_interrupt(). Also balance the runtime pm get() operation
that triggered this processing.

Cc: stable@vger.kernel.org
Fixes: fc8bb91 ("usb: dwc3: implement runtime PM")
Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20230801192658.19275-1-quic_eserrao@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Elson Roy Serrao

drivers/usb/dwc3/gadget.c

@@ -4455,9 +4455,14 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
 	u32 count;
 
 	if (pm_runtime_suspended(dwc->dev)) {
+		dwc->pending_events = true;
+		/*
+		 * Trigger runtime resume. The get() function will be balanced
+		 * after processing the pending events in dwc3_process_pending
+		 * events().
+		 */
 		pm_runtime_get(dwc->dev);
 		disable_irq_nosync(dwc->irq_gadget);
-		dwc->pending_events = true;
 		return IRQ_HANDLED;
 	}
 
@@ -4718,6 +4723,8 @@ void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
 {
 	if (dwc->pending_events) {
 		dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
+		dwc3_thread_interrupt(dwc->irq_gadget, dwc->ev_buf);
+		pm_runtime_put(dwc->dev);
 		dwc->pending_events = false;
 		enable_irq(dwc->irq_gadget);
 	}