From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
git@vger.kernel.org,
Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH 3/4] http.c: avoid danging pointer to local variable `finished`
Date: Tue, 24 May 2022 13:06:02 -0700 [thread overview]
Message-ID: <xmqq35gyhf11.fsf@gitster.g> (raw)
In-Reply-To: <220524.86fskzxsvq.gmgdl@evledraar.gmail.com> ("Ævar Arnfjörð Bjarmason"'s message of "Tue, 24 May 2022 09:58:51 +0200")
Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> On Tue, May 24 2022, Johannes Schindelin via GitGitGadget wrote:
>
>> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>> [...]
>> Let's drop that local variable and introduce a new flag in the slot that
>> is used to indicate that even while the slot is no longer in use, it is
>> still reserved until further notice. It is the responsibility of
>> `run_active_slot()` to clear that flag once it is done with that slot.
>>
>> Initial-patch-by: Junio C Hamano <gitster@pobox.com>
>
> Don't you mean by me?
> I.e. https://lore.kernel.org/git/patch-1.1-1cec367e805-20220126T212921Z-avarab@gmail.com/
Most likely, but this version is so distant from the "clear
slot->finished before leaving run_active_slot()" Dscho and I were
recently discussing, that I do not think it can be said to have been
derived from that one. This is completely a different patch that
makes different changes.
The "clear slot->finished", by the way, is what I think is the right
thing to do, especially that the objective is to squelch the false
positive warning from a new compiler. If there is a way to annotate
the line for the compiler to tell it not to warn about it, that would
have been even better.
> This seems to be derived from that, or perhaps you just came up with
> something similar independently. Junio then came up with the smaller
> https://lore.kernel.org/git/xmqq8rv2nggn.fsf@gitster.g/
I actually do not think so. Yours is revert of the existing fix the
compiler is confused about, and I have a feeling that if the original
fix is still relevant, the problem the original fix wanted to address
will resurface as a regression.
If I am reading the patch correctly, Dscho's is to avoid [*] reusing
a slot while any run_active_slot() is still waiting for its
completion. The approach would solve the problem the original fix
wanted to solve in a different way. Personally I do not think such
a surgery is necessary only to squelch false positives from a new
warning compiler, though.
[Footnote]
* I said "is to avoid", not "avoids", because I haven't studied the
patch with sufficient degree of carefulness to say for sure, even
though I can see that is the intent.
next prev parent reply other threads:[~2022-05-24 20:06 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-24 0:23 [PATCH 0/4] ci: fix windows-build with GCC v12.x Johannes Schindelin via GitGitGadget
2022-05-24 0:23 ` [PATCH 1/4] compat/win32/syslog: fix use-after-realloc Johannes Schindelin via GitGitGadget
2022-05-24 12:39 ` Johannes Schindelin
2022-05-24 20:58 ` Junio C Hamano
2022-05-24 0:23 ` [PATCH 2/4] nedmalloc: avoid new compile error Johannes Schindelin via GitGitGadget
2022-05-24 8:00 ` Ævar Arnfjörð Bjarmason
2022-05-24 15:59 ` René Scharfe
2022-05-24 20:46 ` Johannes Schindelin
2022-05-24 21:33 ` Ævar Arnfjörð Bjarmason
2022-05-24 0:23 ` [PATCH 3/4] http.c: avoid danging pointer to local variable `finished` Johannes Schindelin via GitGitGadget
2022-05-24 7:58 ` Ævar Arnfjörð Bjarmason
2022-05-24 20:06 ` Junio C Hamano [this message]
2022-05-24 21:15 ` Johannes Schindelin
2022-05-24 21:45 ` Ævar Arnfjörð Bjarmason
2022-05-24 22:38 ` Junio C Hamano
2022-05-25 10:16 ` Johannes Schindelin
2022-05-25 12:48 ` Ævar Arnfjörð Bjarmason
2022-05-24 0:23 ` [PATCH 4/4] dir.c: avoid "exceeds maximum object size" error with GCC v12.x Johannes Schindelin via GitGitGadget
2022-05-24 5:53 ` Ævar Arnfjörð Bjarmason
2022-05-24 21:05 ` Johannes Schindelin
2022-05-25 13:39 ` Derrick Stolee
2022-05-25 18:27 ` Junio C Hamano
2022-05-24 15:54 ` [PATCH 0/4] ci: fix windows-build " Jeff Hostetler
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