Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750980AbbFXVOg (ORCPT ); Wed, 24 Jun 2015 17:14:36 -0400 Received: from mga03.intel.com ([134.134.136.65]:10955 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750780AbbFXVO2 (ORCPT ); Wed, 24 Jun 2015 17:14:28 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,673,1427785200"; d="scan'208";a="734021479" Date: Wed, 24 Jun 2015 14:11:48 -0700 (PDT) From: Vikas Shivappa X-X-Sender: vikas@vshiva-Udesk To: Thomas Gleixner cc: Vikas Shivappa , linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, mingo@kernel.org, tj@kernel.org, peterz@infradead.org, matt.fleming@intel.com, will.auld@intel.com, glenn.p.williamson@intel.com, kanaka.d.juvva@intel.com, priya.v.autee@intel.com Subject: Re: [PATCH 01/10] cpumask: Introduce cpumask_any_online_but In-Reply-To: Message-ID: References: <1435100183-21720-1-git-send-email-vikas.shivappa@linux.intel.com> <1435100183-21720-2-git-send-email-vikas.shivappa@linux.intel.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1970 Lines: 64 On Wed, 24 Jun 2015, Thomas Gleixner wrote: > On Tue, 23 Jun 2015, 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..ea63b65 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) >> +{ >> + static cpumask_t tmp; > > How is that supposed to work? > > You cannot expect, that all potential users of this function are > magically serialized. I am trying do something wierd with this API. trying to do cpumask_and_any_but. But anything with 'and' operation, usually the caller supplies the dst. Guess I can remove this API altogether and 'and' the online and package cpu masks during hot cpu notifications. Thanks, Vikas > >> + >> + cpumask_and(&tmp, cpu_online_mask, mask); >> + cpumask_clear_cpu(cpu, &tmp); >> + return cpumask_any(&tmp); > > Thanks, > > tglx > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/