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
next prev parent 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
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