On Wed, 28 May 2014, Michael Ellerman wrote: > On Tue, 2014-05-27 at 01:02 -0400, Vince Weaver wrote: > > On Tue, 27 May 2014, Michael Ellerman wrote: > > > > > On Mon, 2014-05-26 at 20:41 -0400, Dave Jones wrote: > > > > On Mon, May 26, 2014 at 10:32:01PM +1000, Michael Ellerman wrote: > > > > > Some syscalls return ENOSYS depending on their arguments. We don't want > > > > > to stop calling them just because we hit one of those cases. Add a flag > > > > > to specify this behaviour so we don't have to keep special-casing those > > > > > calls in mkcall(). > > > > > > > > I was hopeful this list wouldn't grow, but that doesn't seem to be > > > > the case. Begrudgingly, I applied this. It's going to be a lot > > > > cleaner to maintain if people keep doing this. > > > > > > Yeah it's annoying for sure, maybe perf will be the last one, but at least > > > there's a clean way to handle it if not. > > > > As the author of the man page that you probably got the perf ENOSYS info > > from, I have to put out there that perf_event_open() has really > > inconsistent and confusing error return values, and they vary among the > > various architectures. > > Actually I didn't read the man page, but thanks for reminding me that it > exists. And yes I am aware of your dislike of the perf interface. I had just recently contributed an improved "ERRORS" section to the perf_event_open manpage that tries to be complete, but I'm sure I missed some corner cases. It does document the odd choice of returning ENOSYS in the PERF_SAMPLE_STACK_USER case. It's a shame there isn't some sort of automated tool that could spit out all possible system call return values, it would make it a lot easier to keep things consistent. Vince -- To unsubscribe from this list: send the line "unsubscribe trinity" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
