On Wed, Jul 16, 2025 at 11:57:51PM -0400, Steven Rostedt wrote: > On Wed, 16 Jul 2025 19:01:06 -0700 > Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > > + if (unwind_user_get_reg(&ra, frame->ra.regnum)) > > > + goto done; > > > + break; > > > + default: > > > + WARN_ON_ONCE(1); > > > + goto done; > > > > The default case will never happen, can we make it a BUG()? > > Is this really serious enough to crash the system? WARN_ON_ONCE() *is* for > things that will never happen. > > The only time I ever use BUG() is if it's too dangerous to continue (like a > function graph trampoline that gets corrupted and has no place to return > to). In general, usage of BUG() should be avoided. This is an unreachable code path, but __builtin_unreachable() is crap due to undefined behavior. IMO, BUG() for unreachable paths is cleaner than WARN_ON_ONCE(), but it doesn't matter much either way I suppose. -- Josh
