From: Mark H Weaver <mhw@netris.org>
To: Andy Wingo <wingo@igalia.com>
Cc: 28211@debbugs.gnu.org
Subject: bug#28211: Grafting code triggers GC/thread-safety issue on Guile 2.2.2
Date: Thu, 10 May 2018 02:50:32 -0400 [thread overview]
Message-ID: <87fu30dmx3.fsf@netris.org> (raw)
In-Reply-To: <871sel6vnq.fsf@igalia.com> (Andy Wingo's message of "Wed, 09 May 2018 11:11:21 +0200")
Hi Andy,
Andy Wingo <wingo@igalia.com> writes:
> On Wed 09 May 2018 02:32, Mark H Weaver <mhw@netris.org> writes:
>
>> However, I think it's _far_ more likely that the NULL argument on the
>> stack was copied from memory shared by multiple threads without proper
>> thread synchronization.
>
> I think this is unlikely on x86 given its total-store-ordering memory
> model. I agree with you about the value of barriers, but I don't think
> they are part of this bug that Ludo is seeing.
I think you're forgetting about the C compiler. It's true that x86
machine code has a TSO memory model, but C does not. In the absence of
barriers, the C compiler may freely reorder stores to non-volatile,
non-atomic objects. In particular, it is free to reorder the
initialization of an object with the write of that object's address.
I admit that I haven't checked whether GCC 5.5.0 does this in practice.
Do you have reason to believe that it never does so?
Thanks,
Mark
next prev parent reply other threads:[~2018-05-10 6:52 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-23 22:20 bug#28211: Grafting code triggers GC/thread-safety issue on Guile 2.2.2 Ludovic Courtès
2017-08-23 22:48 ` Ludovic Courtès
2018-04-24 16:03 ` Ludovic Courtès
2018-05-08 21:55 ` Ludovic Courtès
2018-05-09 0:32 ` Mark H Weaver
2018-05-09 7:17 ` Ludovic Courtès
2018-05-09 9:11 ` Andy Wingo
2018-05-10 6:50 ` Mark H Weaver [this message]
2018-05-10 7:53 ` Andy Wingo
2018-06-29 15:03 ` bug#28211: Stack marking issue in multi-threaded code Ludovic Courtès
2018-06-29 16:54 ` Mark H Weaver
2018-06-29 21:18 ` Ludovic Courtès
2018-06-29 23:18 ` Mark H Weaver
2018-06-30 20:53 ` Ludovic Courtès
2018-06-30 21:49 ` Mark H Weaver
2018-07-01 10:12 ` Andy Wingo
2018-07-03 19:01 ` Mark H Weaver
2020-03-12 21:59 ` bug#28211: Stack marking issue in multi-threaded code, 2020 edition Ludovic Courtès
2020-03-13 22:38 ` Ludovic Courtès
2020-03-17 21:16 ` Andy Wingo
2018-05-10 15:48 ` bug#28211: Grafting code triggers GC/thread-safety issue on Guile 2.2.2 Mark H Weaver
2018-05-10 16:01 ` Mark H Weaver
2018-07-02 10:28 ` Ludovic Courtès
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://guix.gnu.org/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87fu30dmx3.fsf@netris.org \
--to=mhw@netris.org \
--cc=28211@debbugs.gnu.org \
--cc=wingo@igalia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/guix.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).