git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: "Martin Ågren" <martin.agren@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Git Mailing List <git@vger.kernel.org>
Subject: Re: [PATCH v2 3/4] strbuf_setlen: don't write to strbuf_slopbuf
Date: Wed, 23 Aug 2017 19:43:01 +0200	[thread overview]
Message-ID: <CAN0heSoqnEx=vPVZ5-OfqMkzL_JKKoa+iyP=G5h-cnqOwjPPYg@mail.gmail.com> (raw)
In-Reply-To: <xmqq378i19ku.fsf@gitster.mtv.corp.google.com>

On 23 August 2017 at 19:24, Junio C Hamano <gitster@pobox.com> wrote:
> Martin Ågren <martin.agren@gmail.com> writes:
>
>> strbuf_setlen(., 0) writes '\0' to sb.buf[0], where buf is either
>> allocated and unique to sb, or the global slopbuf. The slopbuf is meant
>> to provide a guarantee that buf is not NULL and that a freshly
>> initialized buffer contains the empty string, but it is not supposed to
>> be written to. That strbuf_setlen writes to slopbuf has at least two
>> implications:
>>
>> First, it's wrong in principle. Second, it might be hiding misuses which
>> are just waiting to wreak havoc. Third, ThreadSanitizer detects a race
>> when multiple threads write to slopbuf at roughly the same time, thus
>> potentially making any more critical races harder to spot.
>
> There are two hard things in computer science ;-).

Indeed. :-)

>> Suggested-by: Junio C Hamano <gitster@pobox.com>
>> Signed-off-by: Martin Ågren <martin.agren@gmail.com>
>> ---
>> v2: no "ifdef TSAN"; moved check from strbuf_reset into strbuf_setlen
>
> Looks much better.  I have a mild objection to "suggested-by",
> though.  It makes it sound as if this were my itch, but it is not.
>
> All the credit for being motivate to fix the issue should go to you.
> For what I did during the review of the previous one to lead to this
> simpler version, if you want to document it, "helped-by" would be
> more appropriate.

Ok, so that's two things to tweak in the commit message. I'll hold off
on v3 in case I get some more feedback the coming days. Thanks.

Martin

  reply	other threads:[~2017-08-23 17:43 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-15 12:53 [PATCH/RFC 0/5] Some ThreadSanitizer-results Martin Ågren
2017-08-15 12:53 ` [PATCH 1/5] convert: initialize attr_action in convert_attrs Martin Ågren
2017-08-15 14:17   ` Torsten Bögershausen
2017-08-15 14:29     ` Torsten Bögershausen
2017-08-15 14:40     ` Martin Ågren
2017-08-15 12:53 ` [PATCH 2/5] pack-objects: take lock before accessing `remaining` Martin Ågren
2017-08-15 19:50   ` Johannes Sixt
2017-08-15 12:53 ` [PATCH 3/5] Makefile: define GIT_THREAD_SANITIZER Martin Ågren
2017-08-15 12:53 ` [PATCH 4/5] strbuf_reset: don't write to slopbuf with ThreadSanitizer Martin Ågren
2017-08-15 18:43   ` Junio C Hamano
2017-08-15 19:06     ` Martin Ågren
2017-08-15 19:19       ` Junio C Hamano
2017-08-15 12:53 ` [PATCH 5/5] ThreadSanitizer: add suppressions Martin Ågren
2017-08-15 12:53 ` tsan: t3008: hashmap_add touches size from multiple threads Martin Ågren
2017-08-15 17:59   ` Jeff Hostetler
2017-08-15 18:17     ` Stefan Beller
2017-08-15 18:40       ` Martin Ågren
2017-08-15 18:48         ` Stefan Beller
2017-08-15 19:21           ` Martin Ågren
2017-08-15 20:46             ` Jeff Hostetler
2017-08-30 18:59   ` [PATCH] hashmap: address ThreadSanitizer concerns Jeff Hostetler
2017-08-30 18:59     ` [PATCH] hashmap: add API to disable item counting when threaded Jeff Hostetler
2017-09-01 23:31       ` Johannes Schindelin
2017-09-01 23:50         ` Jonathan Nieder
2017-09-05 16:39           ` Jeff Hostetler
2017-09-05 17:13             ` Martin Ågren
2017-09-02  8:17         ` Jeff King
2017-09-04 15:59           ` Johannes Schindelin
2017-09-05 16:54           ` Jeff Hostetler
2017-09-06  3:43           ` Junio C Hamano
2017-09-05 16:33         ` Jeff Hostetler
2017-09-02  8:05       ` Jeff King
2017-09-05 17:07         ` Jeff Hostetler
2017-09-02  8:39       ` Simon Ruderich
2017-09-06  1:24       ` Junio C Hamano
2017-09-06 15:33         ` Jeff Hostetler
2017-09-06 15:43     ` [PATCH v2] hashmap: address ThreadSanitizer concerns Jeff Hostetler
2017-09-06 15:43       ` [PATCH v2] hashmap: add API to disable item counting when threaded Jeff Hostetler
2017-08-15 12:53 ` tsan: t5400: set_try_to_free_routine Martin Ågren
2017-08-15 17:35   ` Stefan Beller
2017-08-15 18:44     ` Martin Ågren
2017-08-17 10:57   ` Jeff King
2017-08-20 10:06 ` [PATCH/RFC 0/5] Some ThreadSanitizer-results Jeff King
2017-08-20 10:45   ` Martin Ågren
2017-08-21 17:43 ` [PATCH v2 0/4] " Martin Ågren
2017-08-21 17:43   ` [PATCH v2 1/4] convert: always initialize attr_action in convert_attrs Martin Ågren
2017-08-21 17:43   ` [PATCH v2 2/4] pack-objects: take lock before accessing `remaining` Martin Ågren
2017-08-21 17:43   ` [PATCH v2 3/4] strbuf_setlen: don't write to strbuf_slopbuf Martin Ågren
2017-08-23 17:24     ` Junio C Hamano
2017-08-23 17:43       ` Martin Ågren [this message]
2017-08-23 18:30         ` Junio C Hamano
2017-08-23 20:37     ` Brandon Casey
2017-08-23 21:04       ` Junio C Hamano
2017-08-23 21:20         ` Brandon Casey
2017-08-23 21:54           ` Brandon Casey
2017-08-23 22:11             ` Brandon Casey
2017-08-24 16:52             ` Junio C Hamano
2017-08-24 18:29               ` Brandon Casey
2017-08-24 19:16                 ` Martin Ågren
2017-08-23 22:24           ` Junio C Hamano
2017-08-23 22:39             ` Brandon Casey
2017-08-21 17:43   ` [PATCH v2 4/4] ThreadSanitizer: add suppressions Martin Ågren
2017-08-25 17:04     ` Jeff King
2017-08-28 20:56   ` [PATCH v2 0/4] Some ThreadSanitizer-results Jeff Hostetler

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: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAN0heSoqnEx=vPVZ5-OfqMkzL_JKKoa+iyP=G5h-cnqOwjPPYg@mail.gmail.com' \
    --to=martin.agren@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.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://80x24.org/mirrors/git.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).