From patchwork Mon Feb 6 11:38:52 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 93411 Delivered-To: patch@linaro.org Received: by 10.140.20.99 with SMTP id 90csp1666206qgi; Mon, 6 Feb 2017 03:40:07 -0800 (PST) X-Received: by 10.99.103.133 with SMTP id b127mr12665589pgc.168.1486381207651; Mon, 06 Feb 2017 03:40:07 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id r5si433800pgn.172.2017.02.06.03.40.07; Mon, 06 Feb 2017 03:40:07 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751814AbdBFLkG (ORCPT + 25 others); Mon, 6 Feb 2017 06:40:06 -0500 Received: from foss.arm.com ([217.140.101.70]:55826 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751221AbdBFLkE (ORCPT ); Mon, 6 Feb 2017 06:40:04 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D3F96707; Mon, 6 Feb 2017 03:40:03 -0800 (PST) Received: from leverpostej.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CAD6C3F3D6; Mon, 6 Feb 2017 03:40:02 -0800 (PST) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: Mark Rutland , Thomas Gleixner , Andrew Morton , Peter Zijlstra , Rusty Russell Subject: [PATCH] cpumask: add cpumask_any_and_but() Date: Mon, 6 Feb 2017 11:38:52 +0000 Message-Id: <1486381132-5610-1-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In some cases, it's useful to be able to select a random cpu from the intersection of two masks, excluding a particular CPU. For example, in some systems an uncore PMU is shared by a subset of CPUs, and management of this PMU is assigned to some arbitrary CPU in this set. Whenever the management CPU is hotplugged out, we wish to migrate responsibility to another arbitrary CPU which is both in this set and online. Today we can use cpumask_any_and() to select an arbitrary CPU in the intersection of two masks. We can also use cpumask_any_but() to select any arbitrary cpu in a mask excluding, a particular CPU. To do both, we either need to use a temporary cpumask, which is wasteful, or use some lower-level cpumask helpers, which can be unclear. This patch adds a new cpumask_any_and_but() to cater for these cases. Signed-off-by: Mark Rutland Cc: Thomas Gleixner Cc: Andrew Morton Cc: Peter Zijlstra Cc: Rusty Russell Cc: linux-kernel@vger.kernel.org --- include/linux/cpumask.h | 3 +++ lib/cpumask.c | 23 +++++++++++++++++++++++ 2 files changed, 26 insertions(+) This patch would help in cases like the Qualcomm L2 cache PMU driver [1]. If people are happy with this patch, I'd like to take it along with that patch (modified to use the new helper). I'm also happy to leave this as a subsequent cleanup. Thanks, Mark. [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-February/485762.html -- 1.9.1 Acked-by: Rusty Russell diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index c717f5e..99dc550 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -210,6 +210,9 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp) int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *); int cpumask_any_but(const struct cpumask *mask, unsigned int cpu); +int cpumask_any_and_but(const struct cpumask *mask1, + const struct cpumask *mask2, + unsigned int cpu); unsigned int cpumask_local_spread(unsigned int i, int node); /** diff --git a/lib/cpumask.c b/lib/cpumask.c index 81dedaa..641b526 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -43,6 +43,29 @@ int cpumask_any_but(const struct cpumask *mask, unsigned int cpu) } EXPORT_SYMBOL(cpumask_any_but); +/** + * cpumask_any_and_but - pick a "random" cpu from *mask1 & *mask2, but not this one. + * @mask1: the first input cpumask + * @mask2: the second input cpumask + * @cpu: the cpu to ignore + * + * Returns >= nr_cpu_ids if no cpus set. + */ +int cpumask_any_and_but(const struct cpumask *mask1, + const struct cpumask *mask2, + unsigned int cpu) +{ + unsigned int i; + + cpumask_check(cpu); + i = cpumask_first_and(mask1, mask2); + if (i != cpu) + return i; + + return cpumask_next_and(cpu, mask1, mask2); +} +EXPORT_SYMBOL(cpumask_any_and_but); + /* These are not inline because of header tangles. */ #ifdef CONFIG_CPUMASK_OFFSTACK /**