Re: [PATCH 1/4] fs: Implement close-on-fork

Matthew Wilcox
2020-04-22T15:44:04Z

On Wed, Apr 22, 2020 at 03:36:09PM +0000, Karstens, Nate wrote:
> There was some skepticism about whether our practice of
> closing/reopening sockets was advisable. Regardless, it does expose what
> I believe to be something that was overlooked in the forking process
> model. We posted two solutions to the Austin Group defect tracker:

I don't think it was "overlooked" at all. It's not safe to call system()
from a threaded app. That's all. It's right there in the DESCRIPTION:

The system() function need not be thread-safe.
https://pubs.opengroup.org/onlinepubs/9699919799/functions/system.html

> Ultimately the Austin Group felt that close-on-fork
> was the preferred approach. I think it's also worth
> pointing that out Solaris reportedly has this feature
> (https://www.mail-archive.com/austin-group-l@opengroup.org/msg05359.html).

I am perplexed that the Austin Group thought this was a good idea.