> -----Original Message----- > From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb- > owner@xxxxxxxxxxxxxxx] On Behalf Of Felipe Balbi > Sent: Wednesday, December 28, 2016 8:19 AM > To: Janusz Dziedzic <janusz.dziedzic@xxxxxxxxx> > Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>; Baolin Wang > <baolin.wang@xxxxxxxxxx>; Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>; USB > <linux-usb@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>; Linaro > Kernel Mailman List <linaro-kernel@xxxxxxxxxxxxxxxx>; Mark Brown > <broonie@xxxxxxxxxx> > Subject: Re: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt > handler and irq thread handler > > > Hi, > > Janusz Dziedzic <janusz.dziedzic@xxxxxxxxx> writes: > >>>> 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? > >> > >> this is top half handler. Interrupts are already disabled. > >> > > BTW, > > We don't use spin_lock in top half handler. > > Maybe we should/can switch all spin_lock_irqsave() to simple > > spin_lock() in the thread/callbacks? > > in theory, yes we've masked all interrupts from this controller for the > duration of the thread handler. However this breaks networking > gadgets. I can only guess network stack has a hard requirement to run > with IRQs disabled. > Hi, Is this version 3.00a of the core? That version has a STAR where the interrupts cannot be masked. That results in similar symptoms to what you're seeing here. Regards, John -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
