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From: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
To: Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Martin Brandenburg
	<martin-gqc3UtWaqJ5Wk0Htik3J/w@public.gmane.org>,
	linux-cachefs-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-aio-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	David Airlie <airlied-cv59FeDIM0c@public.gmane.org>,
	samba-technical
	<samba-technical-w/Ol4Ecudpl8XjKLYN78aQ@public.gmane.org>,
	Joonas Lahtinen
	<joonas.lahtinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
	dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Chris Mason <clm-b10kYP2dOMg@public.gmane.org>,
	dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	keyrings-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-afs-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Mike Marshall <hubcap-gqc3UtWaqJ5Wk0Htik3J/w@public.gmane.org>,
	linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	rds-devel-N0ozoZBvEnrZJqsBc5GL+g@public.gmane.org,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	James Morris <jmorris-gx6/JNMH7DfYtjvyW6yDsg@public.gmane.org>,
	cluster-devel
	<cluster-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Antti Palosaari <crope-X3B1VOXEql0@public.gmane.org>,
	Matthias Brugger
	<matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Paul McKenney
	<paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
	intel-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.orgd
Subject: Re: [RFC][PATCH] wake_up_var() memory ordering
Date: Tue, 25 Jun 2019 15:27:36 +0200	[thread overview]
Message-ID: <20190625132736.GZ3419@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHc6FU6zUCdQZ1AfN2KYcPYVKc5bwvc0bD7=-KZpFXws+F9QZQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Tue, Jun 25, 2019 at 02:12:22PM +0200, Andreas Gruenbacher wrote:

> > Only if we do as David suggested and make clean_and_wake_up_bit()
> > provide the RELEASE barrier.
> 
> (It's clear_and_wake_up_bit, not clean_and_wake_up_bit.)

Yes, typing hard.

> > That is, currently clear_and_wake_up_bit() is
> >
> >         clear_bit()
> >         smp_mb__after_atomic();
> >         wake_up_bit();
> >

> Now I'm confused because clear_and_wake_up_bit() in mainline does use
> clear_bit_unlock(), so it's the exact opposite of what you just said.

Argh; clearly I couldn't read. And then yes, you're right.

WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] [RFC][PATCH] wake_up_var() memory ordering
Date: Tue, 25 Jun 2019 15:27:36 +0200	[thread overview]
Message-ID: <20190625132736.GZ3419@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHc6FU6zUCdQZ1AfN2KYcPYVKc5bwvc0bD7=-KZpFXws+F9QZQ@mail.gmail.com>

On Tue, Jun 25, 2019 at 02:12:22PM +0200, Andreas Gruenbacher wrote:

> > Only if we do as David suggested and make clean_and_wake_up_bit()
> > provide the RELEASE barrier.
> 
> (It's clear_and_wake_up_bit, not clean_and_wake_up_bit.)

Yes, typing hard.

> > That is, currently clear_and_wake_up_bit() is
> >
> >         clear_bit()
> >         smp_mb__after_atomic();
> >         wake_up_bit();
> >

> Now I'm confused because clear_and_wake_up_bit() in mainline does use
> clear_bit_unlock(), so it's the exact opposite of what you just said.

Argh; clearly I couldn't read. And then yes, you're right.



  parent reply	other threads:[~2019-06-25 13:27 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-24 16:50 [RFC][PATCH] wake_up_var() memory ordering Peter Zijlstra
2019-06-24 16:50 ` [Cluster-devel] " Peter Zijlstra
2019-06-25  7:51 ` David Howells
2019-06-25  7:51   ` [Cluster-devel] " David Howells
     [not found]   ` <32379.1561449061-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2019-06-25  8:11     ` Peter Zijlstra
2019-06-25  8:11       ` [Cluster-devel] " Peter Zijlstra
2019-06-25  9:19 ` Andreas Gruenbacher
2019-06-25  9:19   ` [Cluster-devel] " Andreas Gruenbacher
     [not found]   ` <CAHc6FU7j5iW7WQoxN_OSfvK4zxv_MxTWJpiNsqFW8TEDMX1rjw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-25 10:34     ` Peter Zijlstra
2019-06-25 10:34       ` [Cluster-devel] " Peter Zijlstra
2019-06-25 12:12       ` Andreas Gruenbacher
2019-06-25 12:12         ` [Cluster-devel] " Andreas Gruenbacher
     [not found]         ` <CAHc6FU6zUCdQZ1AfN2KYcPYVKc5bwvc0bD7=-KZpFXws+F9QZQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-25 13:27           ` Peter Zijlstra [this message]
2019-06-25 13:27             ` Peter Zijlstra

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