Re: [PATCH v2] Implement close-on-fork

Ralph Corderoy
2022-06-19T10:42:42Z

Hi Matthew, thanks for replying.

> > The need for O_CLOFORK might be made more clear by looking at a
> > long-standing Go issue, i.e. unrelated to system(3), which was started
> > in 2017 by Russ Cox when he summed up the current race-condition
> > behaviour of trying to execve(2) a newly created file:
> > https://github.com/golang/go/issues/22315.
>
> The problem is that people advocating for O_CLOFORK understand its
> value, but not its cost. Other google employees have a system which
> has literally millions of file descriptors in a single process.
> Having to maintain this extra state per-fd is a cost they don't want
> to pay (and have been quite vocal about earlier in this thread).

So do you agree the userspace issue is best solved by *_CLOFORK and the
problem is how to implement *_CLOFORK at an acceptable cost?

OTOH David Laight was making suggestions on moving the load to the
fork/exec path earlier in the thread, but OTOH Al Viro mentioned a
‘portable solution’, though that could have been to a specific issue
rather than the more general case.

How would you recommend approaching an acceptable cost is progressed?
Iterate on patch versions? Open a bugzilla.kernel.org for central
tracking and linking from the other projects? ..?

--
Cheers, Ralph.