From: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
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: d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events in event cache")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/8670aaf1cf52e7d1e6df2a827af2d77263b93b75.1656380429.git.Thinh.Nguyen@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/dwc3/gadget.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3535,7 +3535,6 @@ static irqreturn_t dwc3_process_event_bu
}
evt->count = 0;
- evt->flags &= ~DWC3_EVENT_PENDING;
ret = IRQ_HANDLED;
/* Unmask interrupt */
@@ -3548,6 +3547,9 @@ static irqreturn_t dwc3_process_event_bu
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;
}
