Thread (24 messages) 24 messages, 11 authors, 2022-06-28

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

From: Ralph Corderoy <hidden>
Date: 2022-06-19 10:42:41
Also in: linux-alpha, linux-arch, linux-fsdevel, lkml, sparclinux

Hi Matthew, thanks for replying.
quoted
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.
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