On Mon, Oct 02, 2023 at 11:41:58PM +0200, Uwe Kleine-König wrote: > Hello Greg, > > On Mon, Oct 02, 2023 at 04:53:05PM +0200, Greg Kroah-Hartman wrote: > > On Mon, Oct 02, 2023 at 04:49:59PM +0200, Uwe Kleine-König wrote: > > > On Mon, Oct 02, 2023 at 04:39:47PM +0200, Greg Kroah-Hartman wrote: > > > > On Thu, Sep 14, 2023 at 10:02:51PM +0200, Uwe Kleine-König wrote: > > > > > @@ -469,8 +469,17 @@ static int mtu3_remove(struct platform_device *pdev) > > > > > ssusb_gadget_exit(ssusb); > > > > > ssusb_host_exit(ssusb); > > > > > break; > > > > > - default: > > > > > - return -EINVAL; > > > > > + case USB_DR_MODE_UNKNOWN: > > > > > + /* > > > > > + * This cannot happen because with dr_mode == > > > > > + * USB_DR_MODE_UNKNOWN, .probe() doesn't succeed and so > > > > > + * .remove() wouldn't be called at all. However (little > > > > > + * surprising) the compiler isn't smart enough to see that, so > > > > > + * we explicitly have this case item to not make the compiler > > > > > + * wail about an unhandled enumeration value. > > > > > + */ > > > > > + WARN_ON(1); > > > > > > > > Please don't add new WARN_ON() calls to the kernel, print out a big > > > > error message and return, don't reboot the machine. > > > > > > Huh, printing out an loud error message was my intention. It's news to > > > me that WARN_ON() reboots the machine?! I thought BUG_ON() was the one > > > with the effects you describe that I shouldn't use. > > > > panic-on-warn is set for zillions[1] of Linux systems out there, so systems > > will reboot. > > The people enabling panic-on-warn *ask* for a reboot if something > strange happens, right? If ssusb->dr_mode is USB_DR_MODE_UNKNOWN in > .remove() but wasn't in .probe(), that's strange, right? If I don't > enable panic-on-warn, my system just emits a warning and then the driver > copes with what it has, right? Sounds to me as if WARN_ON does exactly > what is the right thing here. I really don't want to add more WARN_ON() to the kernel if at all possible. If this "can not happen" then just don't even add code for it, why have this at all? The compiler warning can be handled a different way, right? thanks, greg k-h
