On Sat, May 30, 2020 at 09:42:46AM +0900, Tetsuo Handa wrote: > On 2020/05/30 5:41, Andrey Konovalov wrote: > > On Thu, May 28, 2020 at 10:58 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > >> This sounds like a bug in the driver. What would it do if someone had a > >> genuine (not emulated) but buggy USB device which didn't send the > >> desired response? The only way to unblock the driver would be to unplug > >> the device! That isn't acceptable behavior. > > > > OK, that's what I thought. > > I believe that this is not a bug in the driver but a problem of hardware > failure. Unless this is high-availability code which is designed for safely > failing over to other node, we don't need to care about hardware failure. Oh my! I can't even imagine what Linus would say if he saw that... :-( Have you heard of Bad USB? The kernel most definitely does need to protect itself against misbehaving hardware. Let's just leave it at that. If you don't believe me, ask Greg KH. I admit, causing a driver to hang isn't the worst thing a buggy device can do. But the kernel is supposed to be able to cope with such things gracefully. Alan Stern
