Subject: Re: [PATCH bpf-next 1/4] bpf: fix lockdep false positive in percpu_freelist

From: Peter Zijlstra <[email-masked]>
Date: Wed, 30 Jan 2019 20:53:13 +0100

On Wed, Jan 30, 2019 at 11:27:54AM -0800, Alexei Starovoitov wrote:
> On Wed, Jan 30, 2019 at 11:21:26AM +0100, Peter Zijlstra wrote:
> > On Tue, Jan 29, 2019 at 08:04:55PM -0800, Alexei Starovoitov wrote:
> > > 
> > > It has been explained that is a false positive here:
> > > https://lkml.org/lkml/2018/7/25/756
> > 
> > Please, no external references like that. The best option is to fully
> 
> I strongly disagree.
> We allowed all kinds of external links in bpf tree in the past and
> going to continue doing so in the future.
> I'm perfectly aware that some of them will go stale in a day or
> in a year.

What's the point of adding URLs if you know they'll not be useful later?

Anyway, your tree, so you get to make the rules, but personally I've
cursed about this exact issue a fair few times.

See for example the x86 tree policy of creating BZ entries to store
Intel documents to refer to them from commits because the Intel website
is notoriously flaky wrt persistence.

There's nothing worse than references to a document you can no longer
find while trying to make sense of this 3 year old code that suddenly
comes apart.