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: d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events in event cache")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
---
drivers/usb/dwc3/gadget.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 8716bece1072..0d89dfa6eef5 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4249,7 +4249,6 @@ 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 */
@@ -4261,6 +4260,9 @@ 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;
}
base-commit: 03c765b0e3b4cb5063276b086c76f7a612856a9a
--
2.28.0
