Re: [tip:perf/core] perf: Fix broken union in ' struct perf_event_mmap_page'

[Ingo Molnar <mingo@kernel.org>]

* Stephane Eranian <eranian@googlemail.com> wrote:

> On Thu, Sep 19, 2013 at 10:43 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Wed, Sep 18, 2013 at 08:33:53PM +0200, Stephane Eranian wrote:
> >> On Wed, Sep 18, 2013 at 5:42 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> >> > On Wed, Sep 18, 2013 at 10:19:32AM -0400, Vince Weaver wrote:
> >> >> Can you point to any code that is fixed by the commit?
> >> >
> >> > I have some, but I don't think a lot of people use it.
> >> >
> >> > Would you be ok with something like the below? It should preserve
> >> > functionality for code that only cares about cap_usr_rdpmc (PAPI).
> >> >
> >> > Stephane, does libpfm use any of these?
> >> >
> >> Yes, there is an example using this. Need to verify it is not broken
> >> currently (self_count.c).
> >
> > So if that only uses cap_usr_rdpmc, you have the same issue as Vince and
> > the proposed solutions would work for you too.
> >
> > If you also use cap_usr_time we've a bit of a problem.
> 
> I need to look at this program again, was written a long time ago. It 
> does not use cap_usr_rdpmc nor cap_use_time for sure.

If it does not use either flag (which in released kernels is really a 
single flag ABI-wise) then it should be fine.

Thanks,

	Ingo