Re: [PATCH 3/4] man/man2/futex.2: Recycle two gmane URLs

[Carlos O'Donell]

On 8/29/25 1:39 PM, Sebastian Andrzej Siewior wrote:
> On 2025-08-29 12:43:26 [-0400], Carlos O'Donell wrote:
> > > index 69df4036ada7f..027e91b826bf1 100644
> > > --- a/man/man2/futex.2
> > > +++ b/man/man2/futex.2
> > > @@ -6,10 +6,10 @@
> > >    .\"
> > >    .\" FIXME Still to integrate are some points from Torvald Riegel's mail of
> > >    .\" 2015-01-23:
> > > -.\"       http://thread.gmane.org/gmane.linux.kernel/1703405/focus=7977
> > > +.\"       https://lore.kernel.org/lkml/1422037788.29655.0.camel@xxxxxxxxxxx
> >
> > Wrong link?
> >
> > Should be this link:
> > https://lore.kernel.org/lkml/1422037145.27573.0.camel@xxxxxxxxxxx/
> >
> > Where the discussion is about the unresolved constraint to guarantee FIFO order.
>
> I thought it is the longer email, the second that day, where he made
> three points. Didn't read it (yet)…

Given the dates and the disjoint set of topics, my suggestion is the link above.

> Now FIFO ordering you say. Is it glibc's side or kernel side? The kernel
> sorts the futex waiters according their (task's) priority. It is not
> FIFO unless the tasks are of equal priority.

The FIFO order question was a kernel-side question wrt futex semantics.
At least that's how I read the thread. And the issue was resolved, but possibly
not documented. Documentation might include stating "FIFO ordering over all
waiters, or even a subset of waiters (at the same priority level) is not
guaranteed."

Torvald was right that for POSIX condition variables we would naturally want
a FIFO wake order so earlier sleepers are woken first.

> So a futex requeue will take the task with the highest priority from
> uaddr1 and move it to uaddr2.

Right.

--
Cheers,
Carlos.