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From: Florian Weimer <fw@deneb.enyo.de>
To: Rich Felker <dalias@libc.org>
Cc: musl@lists.openwall.com
Subject: Re: [musl] Restrictions on child context after multithreaded fork
Date: Sun, 16 Aug 2020 19:11:37 +0200	[thread overview]
Message-ID: <87eeo6ikhi.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <20200816165642.GZ3265@brightrain.aerifal.cx> (Rich Felker's message of "Sun, 16 Aug 2020 12:56:42 -0400")

* Rich Felker:

> On Sun, Aug 16, 2020 at 11:10:37AM +0200, Florian Weimer wrote:
>> * Rich Felker:
>> 
>> > On some inspection, glibc does not actually attempt to make the child
>> > environment unrestricted. The only things it does around fork are:
>> 
>> I think pthread_once initializers that have partially executed are
>> also executed from the start in the child if initialization is
>> requested again.
>
> I don't follow how pthread_once is related. The vast majority of the
> things I found glibc doing no specific handling for are actual mutable
> state not just on-demand initialization.

If a fork happens during a pthread_once initialization, the subsystem
related to that becomes unavailable after fork.  The pthread_once_t
reinitialization logic intends to avoid that.  Like resetting locks
after fork in the new process, it is rather questionable.

  reply	other threads:[~2020-08-16 17:11 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-14 21:41 Rich Felker
2020-08-14 22:02 ` Florian Weimer
2020-08-14 22:14   ` Rich Felker
2020-08-15  0:47 ` A. Wilcox
2020-08-15  2:40   ` Rich Felker
2020-08-15  2:07 ` Ariadne Conill
2020-08-15  3:02   ` Rich Felker
2020-08-15  6:51 ` Timo Teras
2020-08-15 11:51   ` Natanael Copa
2020-08-15 16:25     ` Rich Felker
2020-08-16  1:27       ` Rich Felker
2020-08-16 12:48         ` Natanael Copa
2020-08-16  3:57 ` Rich Felker
2020-08-16  9:10   ` Florian Weimer
2020-08-16 16:56     ` Rich Felker
2020-08-16 17:11       ` Florian Weimer [this message]
2020-08-16 18:33         ` Rich Felker
2020-08-16  7:05 ` Pirmin Walthert
2020-08-16 16:55   ` Rich Felker
2020-09-30 18:38 ` Rich Felker

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