Re: [PATCH] perf tools: enable close-on-exec flag on perf filedescriptor

[Peter Zijlstra]

On Mon, Jan 06, 2014 at 08:27:54AM -0800, Andi Kleen wrote:
> On Mon, Jan 06, 2014 at 11:51:25AM +0100, Yann Droneaud wrote:
> > In a previous patch [1][2], flag PERF_FLAG_FD_CLOEXEC was
> > added to perf_event_open(2) syscall to allows userspace
> > to enable close-on-exec behavor atomically when creating
> > the file descriptor.
> > 
> > This patch makes perf tools use the new flag.
> 
> What is that good for? I can see why for a threaded program, but 
> "perf" is not threaded.

AFAICT its got nothing to do with threaded or not, but only with exec()
and we do in fact call exec() quite a lot in perf.

It ensures we do not leak open perf FDs into our child processes. Now
I'm not entirely sure how we do the exec these days but I think we were
good about not not leaking them anyway, but more paranoia never really
hurts.
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