On Mon, Jul 22, 2024 at 9:38 AM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, Jul 22, 2024 at 09:00:07AM -0400, Chris Wulff wrote: > > On Sun, Jul 21, 2024 at 9:07 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > On Sun, Jul 21, 2024 at 03:20:49PM -0400, crwulff@xxxxxxxxx wrote: > > > > From: Chris Wulff <crwulff@xxxxxxxxx> ... > > The previous check was also hiding the error, and introduced a panic. > > I could add a printk to that error case, though it would be unassociated > > with the gadget that caused the problem. This function does also return > > an error code when it fails, so the calling function can check that and > > print an error. > > Okay. It wouldn't hurt to print out an error message, even if there's > no way to tell which gadget it refers to. A dump_stack() would help in > that regard, but it won't be needed if the guilty party will always be > pretty obvious. > > By the way, how did you manage to trigger this error? None of the > in-kernel gadget drivers are known to have this bug, and both the > gadgetfs and raw_gadget drivers prevent userspace from doing it. Were > you testing a gadget driver that was under development? I am working on adding alternate settings to UAC1/2 gadgets, so this really was a case of trying to make the failure in development easier to deal with. I don't believe there are any problems with existing gadgets causing this. I will add an error message and submit a new version. Perhaps WARN_ON_ONCE would be appropriate here to get that backtrace instead of a printk? > > Alan Stern
