From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH v3 04/11] xen: sched: close potential races when switching scheduler to CPUs Date: Fri, 8 Apr 2016 14:00:05 +0100 Message-ID: <5707AB55.1070005@citrix.com> References: <20160408011204.10762.14241.stgit@Solace.fritz.box> <20160408012345.10762.40393.stgit@Solace.fritz.box> <5707A9A0.7090608@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1aoW1t-0000Rg-6i for xen-devel@lists.xenproject.org; Fri, 08 Apr 2016 13:00:53 +0000 In-Reply-To: <5707A9A0.7090608@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Dario Faggioli , xen-devel@lists.xenproject.org Cc: George Dunlap , Tianyang Chen , Ian Jackson , Robert VanVossen , Josh 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