Re: [GIT PULL] Global signal cleanup

[Linus Torvalds]

On Wed, Aug 6, 2014 at 9:35 PM, Richard Weinberger <richard@xxxxxx> wrote:
>
> It would be nice to see these rules written down somewhere.

The rules have been pretty clear: "don't rebase public trees".

That's always been the basic rule. There are _exceptions_ when
rebasing is the right thing to do, and they all boil down to "lesser
of two evils", but the evils really have to be pretty big.

Possible reasons to rebase:

 (a) It's not public yet. You haven't pushed to kernel.org or any
other public site, and nobody saw you do it.

     You can rebase to your hearts content, although you should still
use sane logic (ie don't rebase on top of random "merge window kernel
of the day" for example: choose a good starting point, like a previous
release, or something else that makes sense)

   "git rebase" is a great tool for a developers own _private_ data.
It's a great way to split patches up in smaller pieces, or to combine
half-way work, or to re-order patches to be more logical. And as long
as you're doing development on your own, there are no downsides as
with the whole next confusion.

 (b) You *really* screwed up, and the downsides of rebasing are
smaller than the downsides of exposing it.

     As in "oops, that half-way commit doesn't even compile or work at
all, so leaving it in that state will screw up anybody trying to find
other bugs with 'git bisect'"

     At the same time, if you do this just before pushing to me, maybe
you should take a step back and say "oops, my tree was completely
broken, maybe I shouldn't push this to Linus just after fixing it".

 (c) You want to clean things up, and you're not even remotely ready
to push things upstream, and while people have *seen* your work,
nobody relies on it or uses it.

     In other words, your branch was a "Work-in-Progress", and you
preferably let people know it was that.

     Again, rebasing just before pushing to me is *not* good. See the
"really screwed up" thing. If it was WIP code, it doesn't suddenly
become release-quality just because you rebase it.

There may be other reasons, but those are the three main ones. In
general, "rebase just before asking somebody to pull" is just a bad
idea. It either fixed some big problem (in which case it should have
gotten more time before being pushed), or it fixes something truly
trivial (in which case the downsides of sudden rebases outweigh the
upsides).

              Linus
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