On 20-08-19 10:52:36, stern@xxxxxxxxxxxxxxxxxxx wrote: > On Wed, Aug 19, 2020 at 01:31:14AM +0000, Peter Chen wrote: > > On 20-08-18 10:46:55, stern@xxxxxxxxxxxxxxxxxxx wrote: > > > On Tue, Aug 18, 2020 at 10:05:51AM +0000, Peter Chen wrote: > > > > > > > > > > > > > > > > diff --git a/drivers/usb/gadget/udc/core.c > > > > > > b/drivers/usb/gadget/udc/core.c index 473e74088b1f..43351b0af569 > > > > > > 100644 > > > > > > --- a/drivers/usb/gadget/udc/core.c > > > > > > +++ b/drivers/usb/gadget/udc/core.c > > > > > > @@ -1386,7 +1386,6 @@ void usb_del_gadget_udc(struct usb_gadget > > > > > > *gadget) { > > > > > > usb_del_gadget(gadget); > > > > > > usb_put_gadget(gadget); > > > > > > - memset(&gadget->dev, 0x00, sizeof(gadget->dev)); > > > > > > > > > > Shouldn't you do this patch earlier in the series, as the > > > > > usb_put_gadget() call could have freed the memory that is being cleared here? > > > > > > > > > > > > > If I did it earlier, it would cause dwc3 break if people do 'git bisect', dwc3 issue is > > > > fixed at patch 5. > > > > > > If you use the patch I posted earlier: > > > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmarc.info%2F%3Fl%3Dlinux-usb%26m%3D159605415210351%26w%3D2&data=02%7C01%7Cpeter.chen%40nxp.com%7Cac0a92404ea34c230dd208d8444f83d3%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637334455595715503&sdata=whweZozRiWD%2B4iRFz7zvEahWAqQYkQQ8tHlRSiU%2Fj7I%3D&reserved=0 > > > > > > instead of this one then dwc3 would continue to work correctly during > > > the intermediate stages of the series. > > > > > > > But at last, we don't want below at .release function > > > > memset(dev, 0, sizeof(*dev)); > > > > It still needs another patch to delete it after dwc3 changes, > > and it changes .release function name to usb_udc_zero_release, > > this change may also not be needed. > > > > Or I only do move memory clear operation at the first patch, and > > delete it at the last patch, it could let the reader not see > > the memory clear operation at the usb_del_gadget during the patch > > series. > > One way or another, the existing code is wrong. I guess the best we can > do for now is to let it remain wrong during the patch series, rather > than changing it to be wrong in a different way. > > To put it another way, we already run the risk of clearing memory that > has been freed. The series does not make that risk any worse, and it > eventually fixes the problem. > > This means your patch should remain in its position at the end of the > series. > Thank. If you think my sequence during the patch series is OK, would you please add your reviewed-by below? https://www.spinics.net/lists/linux-usb/msg199291.html -- Thanks, Peter Chen