From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Parri Subject: Re: [PATCH v3 4/5] Documentation/locking/atomic: Add a litmus test for atomic_set() Date: Thu, 27 Feb 2020 18:43:04 +0100 Message-ID: <20200227174304.GA11666@andrea> References: <20200227004049.6853-1-boqun.feng@gmail.com> <20200227004049.6853-5-boqun.feng@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-wr1-f66.google.com ([209.85.221.66]:33920 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729548AbgB0RnO (ORCPT ); Thu, 27 Feb 2020 12:43:14 -0500 Content-Disposition: inline In-Reply-To: <20200227004049.6853-5-boqun.feng@gmail.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Boqun Feng Cc: linux-kernel@vger.kernel.org, Alan Stern , Will Deacon , Peter Zijlstra , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , "Paul E. McKenney" , Akira Yokosawa , Daniel Lustig , Jonathan Corbet , Mauro Carvalho Chehab , "David S. Miller" , Rob Herring , Greg Kroah-Hartman , Jonathan Cameron , linux-arch@vger.kernel.org, linux-doc@vger.kernel.org On Thu, Feb 27, 2020 at 08:40:48AM +0800, Boqun Feng wrote: > We already use a litmus test in atomic_t.txt to describe the behavior of > an atomic_set() with the an atomic RMW, so add it into atomic-tests > directory to make it easily accessible for anyone who cares about the > semantics of our atomic APIs. > > Additionally, change the sentences describing the test in atomic_t.txt > with better wording. > > Signed-off-by: Boqun Feng > --- > ...c-RMW-ops-are-atomic-WRT-atomic_set.litmus | 24 +++++++++++++++++++ > Documentation/atomic-tests/README | 7 ++++++ > Documentation/atomic_t.txt | 6 ++--- > 3 files changed, 34 insertions(+), 3 deletions(-) > create mode 100644 Documentation/atomic-tests/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus > > diff --git a/Documentation/atomic-tests/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus b/Documentation/atomic-tests/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus > new file mode 100644 > index 000000000000..5dd7f04e504a > --- /dev/null > +++ b/Documentation/atomic-tests/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus > @@ -0,0 +1,24 @@ > +C Atomic-set-observable-to-RMW Nit: s/Atomic-set-observable-to-RMW/Atomic-RMW-ops-are-atomic-WRT-atomic_set > + > +(* > + * Result: Never > + * > + * Test that atomic_set() cannot break the atomicity of atomic RMWs. > + *) > + > +{ > + atomic_t v = ATOMIC_INIT(1); > +} > + > +P0(atomic_t *v) > +{ > + (void)atomic_add_unless(v,1,0); Nit: spaces after commas > +} > + > +P1(atomic_t *v) > +{ > + atomic_set(v, 0); > +} > + > +exists > +(v=2) > diff --git a/Documentation/atomic-tests/README b/Documentation/atomic-tests/README > index ae61201a4271..a1b72410b539 100644 > --- a/Documentation/atomic-tests/README > +++ b/Documentation/atomic-tests/README > @@ -2,3 +2,10 @@ This directory contains litmus tests that are typical to describe the semantics > of our atomic APIs. For more information about how to "run" a litmus test or > how to generate a kernel test module based on a litmus test, please see > tools/memory-model/README. > + > +============ > +LITMUS TESTS > +============ > + > +Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus > + Test that atomic_set() cannot break the atomicity of atomic RMWs. > diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt > index ceb85ada378e..67d1d99f8589 100644 > --- a/Documentation/atomic_t.txt > +++ b/Documentation/atomic_t.txt > @@ -85,10 +85,10 @@ smp_store_release() respectively. Therefore, if you find yourself only using > the Non-RMW operations of atomic_t, you do not in fact need atomic_t at all > and are doing it wrong. > > -A subtle detail of atomic_set{}() is that it should be observable to the RMW > -ops. That is: > +A note for the implementation of atomic_set{}() is that it must not break the > +atomicity of the RMW ops. That is: > > - C atomic-set > + C Atomic-RMW-ops-are-atomic-WRT-atomic_set > > { > atomic_t v = ATOMIC_INIT(1); > -- > 2.25.0 >