Re: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler

From: Lu Baolu
Date: Mon Dec 26 2016 - 23:45:35 EST


On 12/27/2016 10:58 AM, Baolin Wang wrote:
> Hi,
> On 27 December 2016 at 10:39, Lu Baolu <> wrote:
>> Hi,
>> On 12/26/2016 04:01 PM, Baolin Wang wrote:
>>> On some platfroms(like x86 platform), when one core is running the USB gadget
>>> irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can
>>> respond other interrupts from dwc3 controller and modify the event buffer by
>>> dwc3_interrupt() function, that will cause getting the wrong event count in
>>> irq thread handler to make the USB function abnormal.
>>> We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
>> Why not spin_lock_irq ones? This lock seems to be used in both
>> normal and interrupt threads. Or, I missed anything?
> I assumed there are no nested interrupts, when one core is running at
> interrupt context, then it can not respond any other interrupts, which
> means we don't need to disable local IRQ now, right?

Fair enough. Thanks.

Best regards,
Lu Baolu