Re: linux-next: manual merge of the tip tree with the net-next tree

Ingo Molnar
2017-11-01T09:04:11Z

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Wed, Nov 01, 2017 at 09:27:43AM +0100, Ingo Molnar wrote:
> >
> > * Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > On Wed, Nov 01, 2017 at 06:15:54PM +1100, Stephen Rothwell wrote:
> > > > Hi all,
> > > >
> > > > Today's linux-next merge of the tip tree got a conflict in:
> > > >
> > > > kernel/trace/bpf_trace.c
> > > >
> > > > between commits:
> > > >
> > > > 97562633bcba ("bpf: perf event change needed for subsequent bpf helpers")
> > > > and more changes ...
> > > >
> > > > from the net-next tree and commit:
> > > >
> > > > 7d9285e82db5 ("perf/bpf: Extend the perf_event_read_local() interface, a.k.a. "bpf: perf event change needed for subsequent bpf helpers"")
> > > >
> > > > from the tip tree.
> > >
> > > So those should be the exact same patch; except for Changelog and
> > > subject. Code wise there shouldn't be a conflict.
> >
> > So the problem is that then we have:
> >
> > 0d3d73aac2ff ("perf/core: Rewrite event timekeeping")
> >
> > which changes the code. This is a known conflict generation pattern: Git isn't
> > smart enough to sort out that (probably because it would make merges too
> > expensive) - and it's a bad flow in any case.
>
> Hmm, I thought having that same base patch in both trees would allow it
> to resolve that conflict. A well..

I think that would require content level matching of a rather horrifying volume to
resolve, slowing down Git merges horribly. (Maybe there's an option for Git to do
that, but it's not the default I think.)

Thanks,

Ingo