Commit e3184cde authored Jun 27, 2022 by Thinh Nguyen Committed by Greg Kroah-Hartman Jul 21, 2022

usb: dwc3: gadget: Fix event pending check

commit 7441b273388b9a59d8387a03ffbbca9d5af6348c upstream.

The DWC3_EVENT_PENDING flag is used to protect against invalid call to
top-half interrupt handler, which can occur when there's a delay in
software detection of the interrupt line deassertion.

However, the clearing of this flag was done prior to unmasking the
interrupt line, creating opportunity where the top-half handler can
come. This breaks the serialization and creates a race between the
top-half and bottom-half handler, resulting in losing synchronization
between the controller and the driver when processing events.

To fix this, make sure the clearing of the DWC3_EVENT_PENDING is done at
the end of the bottom-half handler.

Fixes: d325a1de ("usb: dwc3: gadget: Prevent losing events in event cache")
Cc: stable@vger.kernel.org
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/8670aaf1cf52e7d1e6df2a827af2d77263b93b75.1656380429.git.Thinh.Nguyen@synopsys.com

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 79c7119f

drivers/usb/dwc3/gadget.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -3187,7 +3187,6 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
		}

		evt->count = 0;
		evt->flags &= ~DWC3_EVENT_PENDING;
		ret = IRQ_HANDLED;

		/* Unmask interrupt */
		@@ -3200,6 +3199,9 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
		dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), dwc->imod_interval);
		}

		/* Keep the clearing of DWC3_EVENT_PENDING at the end */
		evt->flags &= ~DWC3_EVENT_PENDING;

		return ret;
		}