From: Toon Claes <toon@iotcl•com>
To: Patrick Steinhardt <ps@pks•im>, git@vger•kernel.org
Cc: "Karthik Nayak" <karthik.188@gmail•com>,
"Justin Tobler" <jltobler@gmail•com>,
"Junio C Hamano" <gitster@pobox•com>,
"SZEDER Gábor" <szeder.dev@gmail•com>,
"Jeff King" <peff@peff•net>,
"Kristoffer Haugsbakk" <kristofferhaugsbakk@fastmail•com>,
"Ben Knoble" <ben.knoble@gmail•com>
Subject: Re: [PATCH v3 7/9] refs/files: detect race when generating reflog entry for HEAD
Date: Fri, 01 Aug 2025 13:55:31 +0200 [thread overview]
Message-ID: <87seibuuh8.fsf@iotcl.com> (raw)
In-Reply-To: <20250729-pks-reflog-append-v3-7-9614d310f073@pks.im>
Patrick Steinhardt <ps@pks•im> writes:
> When updating a reference that is being pointed to HEAD we don't only
> write a reflog message for that particular reference, but also generate
> one for HEAD. This logic is handled by `split_head_update()`, where we:
>
> 1. Verify that the condition actually triggered. This is done by
> reading HEAD at the start of the transaction so that we can then
> check whether a given reference update refers to its target.
>
> 2. Queue a new log-only update for HEAD in case it did.
>
> But the logic is unfortunately not free of races, as we do not lock the
> HEAD reference after we have read its target. This can lead to the
> following two scenarios:
>
> - HEAD gets concurrently updated to point to one of the references we
> have already processed. This causes us not writing a reflog message
> even though we should have done so.
>
> - HEAD gets concurrently updated to point to not point to a reference
That's a little much of pointing, right? ;)
Maybe change it to something like:
- HEAD gets concurrently updated to no longer point to a reference
--
Cheers,
Toon
next prev parent reply other threads:[~2025-08-01 11:55 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-22 11:20 [PATCH 0/8] refs: fix migration of reflog entries Patrick Steinhardt
2025-07-22 11:20 ` [PATCH 1/8] Documentation/git-reflog: convert to use synopsis type Patrick Steinhardt
2025-07-22 22:04 ` Junio C Hamano
2025-07-22 11:20 ` [PATCH 2/8] builtin/reflog: improve grouping of subcommands Patrick Steinhardt
2025-07-23 18:14 ` Justin Tobler
2025-07-24 7:42 ` Patrick Steinhardt
2025-07-24 16:45 ` Junio C Hamano
2025-07-22 11:20 ` [PATCH 3/8] refs: export `ref_transaction_update_reflog()` Patrick Steinhardt
2025-07-23 18:25 ` Justin Tobler
2025-07-24 8:36 ` Karthik Nayak
2025-07-24 12:55 ` Toon Claes
2025-07-22 11:20 ` [PATCH 4/8] builtin/reflog: implement subcommand to write new entries Patrick Steinhardt
2025-07-23 19:00 ` Justin Tobler
2025-07-24 7:42 ` Patrick Steinhardt
2025-07-24 12:54 ` Toon Claes
2025-07-25 5:36 ` Patrick Steinhardt
2025-07-24 16:20 ` SZEDER Gábor
2025-07-24 21:10 ` Junio C Hamano
2025-07-25 5:36 ` Patrick Steinhardt
2025-07-25 14:35 ` Junio C Hamano
2025-07-22 11:20 ` [PATCH 5/8] ident: fix type of string length parameter Patrick Steinhardt
2025-07-22 11:20 ` [PATCH 6/8] refs: fix identity for migrated reflogs Patrick Steinhardt
2025-07-23 19:41 ` Justin Tobler
2025-07-24 7:42 ` Patrick Steinhardt
2025-07-24 9:41 ` Karthik Nayak
2025-07-24 12:56 ` Toon Claes
2025-07-22 11:20 ` [PATCH 7/8] refs: stop unsetting REF_HAVE_OLD for log-only updates Patrick Steinhardt
2025-07-23 20:31 ` Justin Tobler
2025-07-24 7:42 ` Patrick Steinhardt
2025-07-24 10:21 ` Karthik Nayak
2025-07-24 11:35 ` Patrick Steinhardt
2025-07-22 11:20 ` [PATCH 8/8] refs: fix invalid old object IDs when migrating reflogs Patrick Steinhardt
2025-07-22 22:09 ` Junio C Hamano
2025-07-23 4:04 ` Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 0/8] refs: fix migration of reflog entries Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 1/8] Documentation/git-reflog: convert to use synopsis type Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 2/8] builtin/reflog: improve grouping of subcommands Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 3/8] refs: export `ref_transaction_update_reflog()` Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 4/8] builtin/reflog: implement subcommand to write new entries Patrick Steinhardt
2025-07-28 15:33 ` Kristoffer Haugsbakk
2025-07-28 18:49 ` Junio C Hamano
2025-07-28 20:39 ` Karthik Nayak
2025-07-28 20:59 ` Junio C Hamano
2025-07-30 7:55 ` Karthik Nayak
2025-07-29 0:25 ` Ben Knoble
2025-07-29 6:14 ` Kristoffer Haugsbakk
2025-07-29 6:51 ` Patrick Steinhardt
2025-07-29 15:00 ` Junio C Hamano
2025-07-30 5:33 ` Patrick Steinhardt
2025-07-30 10:33 ` Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 5/8] ident: fix type of string length parameter Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 6/8] refs: fix identity for migrated reflogs Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 7/8] refs: stop unsetting REF_HAVE_OLD for log-only updates Patrick Steinhardt
2025-07-25 11:36 ` Jeff King
2025-07-28 14:43 ` Patrick Steinhardt
2025-07-29 7:14 ` Jeff King
2025-07-29 7:54 ` Patrick Steinhardt
2025-07-25 6:58 ` [PATCH v2 8/8] refs: fix invalid old object IDs when migrating reflogs Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 0/9] refs: fix migration of reflog entries Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 1/9] Documentation/git-reflog: convert to use synopsis type Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 2/9] builtin/reflog: improve grouping of subcommands Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 3/9] refs: export `ref_transaction_update_reflog()` Patrick Steinhardt
2025-08-01 11:38 ` Toon Claes
2025-08-04 7:37 ` Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 4/9] builtin/reflog: implement subcommand to write new entries Patrick Steinhardt
2025-07-29 16:07 ` Junio C Hamano
2025-08-01 11:37 ` Toon Claes
2025-08-04 7:38 ` Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 5/9] ident: fix type of string length parameter Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 6/9] refs: fix identity for migrated reflogs Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 7/9] refs/files: detect race when generating reflog entry for HEAD Patrick Steinhardt
2025-07-29 16:16 ` Junio C Hamano
2025-08-01 11:55 ` Toon Claes [this message]
2025-08-02 11:11 ` Jeff King
2025-08-04 7:38 ` Patrick Steinhardt
2025-08-04 14:47 ` Jeff King
2025-07-29 8:55 ` [PATCH v3 8/9] refs: stop unsetting REF_HAVE_OLD for log-only updates Patrick Steinhardt
2025-07-29 8:55 ` [PATCH v3 9/9] refs: fix invalid old object IDs when migrating reflogs Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 0/9] refs: fix migration of reflog entries Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 1/9] Documentation/git-reflog: convert to use synopsis type Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 2/9] builtin/reflog: improve grouping of subcommands Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 3/9] refs: export `ref_transaction_update_reflog()` Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 4/9] builtin/reflog: implement subcommand to write new entries Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 5/9] ident: fix type of string length parameter Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 6/9] refs: fix identity for migrated reflogs Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 7/9] refs/files: detect race when generating reflog entry for HEAD Patrick Steinhardt
2025-08-04 15:38 ` Jeff King
2025-08-04 9:46 ` [PATCH v4 8/9] refs: stop unsetting REF_HAVE_OLD for log-only updates Patrick Steinhardt
2025-08-04 9:46 ` [PATCH v4 9/9] refs: fix invalid old object IDs when migrating reflogs Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 0/9] refs: fix migration of reflog entries Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 1/9] Documentation/git-reflog: convert to use synopsis type Patrick Steinhardt
2025-08-05 17:04 ` Jean-Noël AVILA
2025-08-05 21:47 ` Junio C Hamano
2025-08-06 5:53 ` Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 2/9] builtin/reflog: improve grouping of subcommands Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 3/9] refs: export `ref_transaction_update_reflog()` Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 4/9] builtin/reflog: implement subcommand to write new entries Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 5/9] ident: fix type of string length parameter Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 6/9] refs: fix identity for migrated reflogs Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 7/9] refs/files: detect race when generating reflog entry for HEAD Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 8/9] refs: stop unsetting REF_HAVE_OLD for log-only updates Patrick Steinhardt
2025-08-05 15:11 ` [PATCH v5 9/9] refs: fix invalid old object IDs when migrating reflogs Patrick Steinhardt
2025-08-05 18:47 ` [PATCH v5 0/9] refs: fix migration of reflog entries Jeff King
2025-08-06 5:53 ` Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 " Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 1/9] Documentation/git-reflog: convert to use synopsis type Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 2/9] builtin/reflog: improve grouping of subcommands Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 3/9] refs: export `ref_transaction_update_reflog()` Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 4/9] builtin/reflog: implement subcommand to write new entries Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 5/9] ident: fix type of string length parameter Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 6/9] refs: fix identity for migrated reflogs Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 7/9] refs/files: detect race when generating reflog entry for HEAD Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 8/9] refs: stop unsetting REF_HAVE_OLD for log-only updates Patrick Steinhardt
2025-08-06 5:54 ` [PATCH v6 9/9] refs: fix invalid old object IDs when migrating reflogs Patrick Steinhardt
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