From: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Junio C Hamano <gitster@pobox.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 19:36:17 -0200 [thread overview]
Message-ID: <20180212193617.4993398a@vento.lan> (raw)
In-Reply-To: <CA+55aFwM0vy+pw-Xv=gA19ULMwAXNPhdO3qR5A3hkMrZKJFNSQ@mail.gmail.com>
Em Mon, 12 Feb 2018 13:15:04 -0800
Linus Torvalds <torvalds@linux-foundation.org> escreveu:
> 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.
Hmm... at least at git version 2.14.3, git documentation doesn't
mention that signed pull requests won't do fast forward. Instead,
it says that --ff is the default behavior:
--ff
When the merge resolves as a fast-forward, only update the branch pointer, without creating a merge commit. This is the
default behavior.
Btw, even doing:
$ git merge -ff v4.16-rc1
it will still produce a git commit for the merge.
--
Thanks,
Mauro
next prev parent reply other threads:[~2018-02-12 21:36 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 ` linux-next: unnecessary merge in the v4l-dvb tree Linus Torvalds
2018-02-12 21:36 ` Mauro Carvalho Chehab [this message]
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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