From: Linus Torvalds <torvalds@linux-foundation.org>
To: Stephen Rothwell <sfr@canb.auug.org.au>,
Junio C Hamano <gitster@pobox.com>
Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Git Mailing List <git@vger.kernel.org>
Subject: Re: linux-next: unnecessary merge in the v4l-dvb tree
Date: Mon, 12 Feb 2018 13:15:04 -0800 [thread overview]
Message-ID: <CA+55aFwM0vy+pw-Xv=gA19ULMwAXNPhdO3qR5A3hkMrZKJFNSQ@mail.gmail.com> (raw)
In-Reply-To: <20180213080036.3bf3a908@canb.auug.org.au>
On Mon, Feb 12, 2018 at 1:00 PM, Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> Linus, this happens a bit after the merge window, so I am wondering
> about the rational of not doing a fast forward merge when merging a
> signed tag (I forget the reasoning).
The reasoning is to avoid losing the signature from the tag (when
merging a signed tag, the signature gets inserted into the merge
commit itself - use "git log --show-signature" to see them).
So when I merge a signed tag, I do *not* want to fast-forward to the
top commit, because then I'd lose the signature from the tag. Thus the
"merging signed tags are non-fast-forward by default" reasoning.
But, yes, that reasoning is really only valid for proper merges of new
features, not for back-merges.
The problem, of course, is that since git is distributed, git doesn't
know who is "upstream" and who is "downstream", so there's no
_technical_ difference between merging a development tree, and a
development tree doing a back-merge of the upstream tree.
Maybe it was a mistake to make signed tag merges non-fast-forward,
since they cause these kinds of issues with people who use "pull" to
update their otherwise unmodified trees.
I can always teach myself to just use --no-ff, since I end up doing
things like verifying at the signatures anyway.
Junio, comments?
Linus
next parent reply other threads:[~2018-02-12 21:15 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180213080036.3bf3a908@canb.auug.org.au>
2018-02-12 21:15 ` Linus Torvalds [this message]
2018-02-12 21:36 ` linux-next: unnecessary merge in the v4l-dvb tree Mauro Carvalho Chehab
2018-02-12 21:37 ` Linus Torvalds
2018-02-12 21:44 ` Junio C Hamano
2018-02-12 21:59 ` Linus Torvalds
2018-02-12 23:42 ` Junio C Hamano
2018-02-13 0:21 ` Mauro Carvalho Chehab
2018-02-13 17:18 ` Junio C Hamano
2018-02-13 17:33 ` Linus Torvalds
2018-02-14 18:12 ` Junio C Hamano
2018-02-15 22:45 ` [PATCH] merge: allow fast-forward when merging a tracked tag Junio C Hamano
2018-02-15 23:34 ` Eric Sunshine
2018-02-16 18:06 ` Junio C Hamano
2018-02-16 21:27 ` [PATCH v2] " Junio C Hamano
2018-02-12 21:37 ` linux-next: unnecessary merge in the v4l-dvb tree Junio C Hamano
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