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Date: Fri, 19 Jul 2019 00:46:28 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: Brooks Davis <brooks@freebsd.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r350116 - head/lib/libc/gen
Message-ID: <20190718214628.GD47193@kib.kiev.ua>
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 <20190718214115.GA42117@spindle.one-eyed-alien.net>
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On Thu, Jul 18, 2019 at 09:41:15PM +0000, Brooks Davis wrote:
> On Thu, Jul 18, 2019 at 09:33:56PM +0000, Brooks Davis wrote:
> > Author: brooks
> > Date: Thu Jul 18 21:33:55 2019
> > New Revision: 350116
> > URL: https://svnweb.freebsd.org/changeset/base/350116
> > 
> > Log:
> >   Document that setmode(3) is not thread safe.
> >   
> >   In some circumstances, setmode(3) may call umask(2) twice to retrieve
> >   the current mode and then restore it.  Between calls, the process will
> >   have a umask of 0.
> 
> This race isn't especially serious, since it only occurs when
> security.bsd.unprivileged_proc_debug=0, but it's probably something to
> fix.  The easiest solution would probably be to implement a getumask()
> syscall.

You can use pthread_suspend_all_np(3).