From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754240AbbFOMg2 (ORCPT ); Mon, 15 Jun 2015 08:36:28 -0400 Received: from casper.infradead.org ([85.118.1.10]:39797 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754077AbbFOMgU (ORCPT ); Mon, 15 Jun 2015 08:36:20 -0400 Date: Mon, 15 Jun 2015 14:36:14 +0200 From: Peter Zijlstra To: Vikas Shivappa Cc: linux-kernel@vger.kernel.org, vikas.shivappa@intel.com, x86@kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@kernel.org, matt.fleming@intel.com, will.auld@intel.com, linux-rdt@eclists.intel.com Subject: Re: [PATCH 01/10] cpumask: Introduce cpumask_any_online_but Message-ID: <20150615123614.GA3644@twins.programming.kicks-ass.net> References: <1434133037-25189-1-git-send-email-vikas.shivappa@linux.intel.com> <1434133037-25189-2-git-send-email-vikas.shivappa@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1434133037-25189-2-git-send-email-vikas.shivappa@linux.intel.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 12, 2015 at 11:17:08AM -0700, Vikas Shivappa wrote: > There is currently no cpumask helper function to pick a "random" cpu > from a mask which is also online. > > cpumask_any_online_but() does that which is similar to cpumask_any_but() > but also returns a cpu that is online. > > Signed-off-by: Vikas Shivappa > --- > include/linux/cpumask.h | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h > index 27e285b..f2d7e8a 100644 > --- a/include/linux/cpumask.h > +++ b/include/linux/cpumask.h > @@ -548,6 +548,24 @@ static inline void cpumask_copy(struct cpumask *dstp, > #define cpumask_of(cpu) (get_cpu_mask(cpu)) > > /** > + * cpumask_any_online_but - return a "random" and online cpu in a cpumask, > + * but not this one > + * @mask: the input mask to search > + * @cpu: the cpu to ignore > + * > + * Returns >= nr_cpu_ids if no cpus set. > +*/ > +static inline unsigned int cpumask_any_online_but(const struct cpumask *mask, > + unsigned int cpu) > +{ > + cpumask_t tmp; No, you cannot put a cpumask_t on stack like that. Those things can be massive. > + > + cpumask_and(&tmp, cpu_online_mask, mask); > + cpumask_clear_cpu(cpu, &tmp); > + return cpumask_any(&tmp); > +} You had a good example in cpumask_any_but() copy that.