From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boqun Feng Subject: [PATCH v3 4/5] Documentation/locking/atomic: Add a litmus test for atomic_set() Date: Thu, 27 Feb 2020 08:40:48 +0800 Message-ID: <20200227004049.6853-5-boqun.feng@gmail.com> References: <20200227004049.6853-1-boqun.feng@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200227004049.6853-1-boqun.feng@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Alan Stern , Andrea Parri , Will Deacon , Peter Zijlstra , Boqun Feng , 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 List-Id: linux-arch.vger.kernel.org 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 + +(* + * 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); +} + +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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f195.google.com ([209.85.222.195]:47095 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727987AbgB0AlK (ORCPT ); Wed, 26 Feb 2020 19:41:10 -0500 From: Boqun Feng Subject: [PATCH v3 4/5] Documentation/locking/atomic: Add a litmus test for atomic_set() Date: Thu, 27 Feb 2020 08:40:48 +0800 Message-ID: <20200227004049.6853-5-boqun.feng@gmail.com> In-Reply-To: <20200227004049.6853-1-boqun.feng@gmail.com> References: <20200227004049.6853-1-boqun.feng@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: Alan Stern , Andrea Parri , Will Deacon , Peter Zijlstra , Boqun Feng , 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 Message-ID: <20200227004048.q0o7HyMWGl1Lkkk4xNhrQyfLhOayIShoexH_Vik3K_A@z> 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 + +(* + * 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); +} + +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