From: Alan Stern <stern@rowland.harvard.edu>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: linux-kernel@vger.kernel.org,
Andrea Parri <parri.andrea@gmail.com>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Nicholas Piggin <npiggin@gmail.com>,
David Howells <dhowells@redhat.com>,
Jade Alglave <j.alglave@ucl.ac.uk>,
Luc Maranget <luc.maranget@inria.fr>,
"Paul E. McKenney" <paulmck@kernel.org>,
Akira Yokosawa <akiyks@gmail.com>,
Daniel Lustig <dlustig@nvidia.com>,
Jonathan Corbet <corbet@lwn.net>, <linux-arch@vger.kernel.org>,
<linux-doc@vger.kernel.org>
Subject: Re: [RFC 2/3] tools/memory-model: Add a litmus test for atomic_set()
Date: Fri, 14 Feb 2020 10:47:48 -0500 (EST) [thread overview]
Message-ID: <Pine.LNX.4.44L0.2002141028280.1579-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <20200214040132.91934-3-boqun.feng@gmail.com>
On Fri, 14 Feb 2020, 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 the litmus-tests
> directory to make it easily accessible for anyone who cares about the
> semantics of our atomic APIs.
>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> ---
> .../Atomic-set-observable-to-RMW.litmus | 24 +++++++++++++++++++
> tools/memory-model/litmus-tests/README | 3 +++
> 2 files changed, 27 insertions(+)
> create mode 100644 tools/memory-model/litmus-tests/Atomic-set-observable-to-RMW.litmus
I don't like that name, or the corresponding sentence in atomic_t.txt:
A subtle detail of atomic_set{}() is that it should be
observable to the RMW ops.
"Observable" doesn't get the point across -- the point being that the
atomic RMW ops have to be _atomic_ with respect to all atomic store
operations, including atomic_set.
Suggestion: Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus, with
corresponding changes to the comment in the litmus test and the entry
in README.
Alan
> diff --git a/tools/memory-model/litmus-tests/Atomic-set-observable-to-RMW.litmus b/tools/memory-model/litmus-tests/Atomic-set-observable-to-RMW.litmus
> new file mode 100644
> index 000000000000..4326f56f2c1a
> --- /dev/null
> +++ b/tools/memory-model/litmus-tests/Atomic-set-observable-to-RMW.litmus
> @@ -0,0 +1,24 @@
> +C Atomic-set-observable-to-RMW
> +
> +(*
> + * Result: Never
> + *
> + * Test of the result of atomic_set() must be observable to atomic RMWs.
> + *)
> +
> +{
> + atomic_t v = ATOMIC_INIT(1);
> +}
> +
> +P0(atomic_t *v)
> +{
> + (void)atomic_add_unless(v,1,0);
> +}
> +
> +P1(atomic_t *v)
> +{
> + atomic_set(v, 0);
> +}
> +
> +exists
> +(v=2)
> diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
> index 681f9067fa9e..81eeacebd160 100644
> --- a/tools/memory-model/litmus-tests/README
> +++ b/tools/memory-model/litmus-tests/README
> @@ -2,6 +2,9 @@
> LITMUS TESTS
> ============
>
> +Atomic-set-observable-to-RMW.litmus
> + Test of the result of atomic_set() must be observable to atomic RMWs.
> +
> CoRR+poonceonce+Once.litmus
> Test of read-read coherence, that is, whether or not two
> successive reads from the same variable are ordered.
>
next prev parent reply other threads:[~2020-02-14 15:47 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 4:01 [RFC 0/3] tools/memory-model: Add litmus tests for atomic APIs Boqun Feng
2020-02-14 4:01 ` [RFC 1/3] Documentation/locking/atomic: Fix atomic-set litmus test Boqun Feng
2020-02-14 4:01 ` [RFC 2/3] tools/memory-model: Add a litmus test for atomic_set() Boqun Feng
2020-02-14 8:12 ` Andrea Parri
2020-02-14 10:40 ` Boqun Feng
2020-02-25 7:34 ` Boqun Feng
2020-02-25 13:01 ` Luc Maranget
2020-02-26 2:51 ` Boqun Feng
2020-02-14 15:47 ` Alan Stern [this message]
2020-02-14 23:52 ` Boqun Feng
2020-02-17 11:02 ` Peter Zijlstra
2020-02-14 4:01 ` [RFC 3/3] tools/memory-model: Add litmus test for RMW + smp_mb__after_atomic() Boqun Feng
2020-02-14 6:15 ` Boqun Feng
2020-02-14 8:18 ` Andrea Parri
2020-02-14 8:20 ` Boqun Feng
2020-02-14 15:58 ` Alan Stern
2020-02-15 0:09 ` Boqun Feng
2020-02-14 9:55 ` [RFC 0/3] tools/memory-model: Add litmus tests for atomic APIs Peter Zijlstra
2020-02-14 10:20 ` Paul E. McKenney
2020-02-14 15:27 ` Alan Stern
2020-02-14 23:39 ` Boqun Feng
2020-02-15 15:25 ` Paul E. McKenney
2020-02-16 5:43 ` Boqun Feng
2020-02-16 12:06 ` Paul E. McKenney
2020-02-16 16:16 ` Alan Stern
2020-02-17 1:27 ` Boqun Feng
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Pine.LNX.4.44L0.2002141028280.1579-100000@iolanthe.rowland.org \
--to=stern@rowland.harvard.edu \
--cc=akiyks@gmail.com \
--cc=boqun.feng@gmail.com \
--cc=corbet@lwn.net \
--cc=dhowells@redhat.com \
--cc=dlustig@nvidia.com \
--cc=j.alglave@ucl.ac.uk \
--cc=linux-arch@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luc.maranget@inria.fr \
--cc=npiggin@gmail.com \
--cc=parri.andrea@gmail.com \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).