From mboxrd@z Thu Jan  1 00:00:00 1970
From: Greg KH <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>
Subject: Re: [RFC PATCH v9 for 4.15 01/14] Restartable sequences system call
Date: Wed, 18 Oct 2017 08:22:26 +0200
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To: Ben Maurer <bmaurer-b10kYP2dOMg@public.gmane.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org>, Andi Kleen <andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org>, carlos <carlos-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, "Paul E. McKenney" <paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, David Goldblatt <davidgoldblatt-b10kYP2dOMg@public.gmane.org>, Qi Wang <qiwang-b10kYP2dOMg@public.gmane.org>, Boqun Feng <boqun.feng-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Paul Turner <pjt-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Andrew Hunter <ahh-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, Dave Watson <davejwatson-b10kYP2dOMg@public.gmane.org>, Josh Triplett <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org>, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>, linux-kernel <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Chris Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>
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On Tue, Oct 17, 2017 at 04:19:41PM +0000, Ben Maurer wrote:
> Hey,
> 
> > So far the restrictions I see for libraries using this symbol are:
> > - They should never be unloaded,
> > - They should never be loaded with dlopen RTLD_LOCAL flag.
> 
> We talked a bit about this off-list but I wanted to state publicly
> that I think this model works well for our use case. Specifically,
> 
> (1) It reduces complexity by focusing on the common case -- long term
> we expect glibc to manage the process of using this feature and
> registering/deregistering threads for rseq. Unloading isn't a
> challenge in these situations, so why add the complexity for it?

You never install a new version of glibc on a running system, and expect
everything to keep running successfully?  Breaking that would not be
good...

thanks,

greg k-h