Re: [RFD] perf syscall error handling

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Mon, Nov 03, 2014 at 05:50:19PM +0100, Peter Zijlstra escreveu:
> On Mon, Nov 03, 2014 at 02:25:48PM -0200, Arnaldo Carvalho de Melo wrote:
 
> > The way that peterz suggested, i.e. returning information about which
> > perf_event_attr and which of the parameters was invalid/had issues could
> > help with fallbacking/capability querying, i.e. tooling may want to use
> > some features if available automagically, fallbacking to something else
> > when that fails.
 
> > We already do that to some degree in various cases, but for some if the
> > only way that becomes available to disambiguate some EINVAL return is a
> > string, code will start having strcmps :-\

> OK, so how about we do both, the offset+mask for the tools and the
> string for the humans?

Yeah, tooling tries to provide the best it can with the offset+mask, and
if doesn't manage to do anything smart with it, just show the string and
hope that helps the user to figure out what is happening.

- Arnaldo