Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758041AbbEVRH3 (ORCPT ); Fri, 22 May 2015 13:07:29 -0400 Received: from mga02.intel.com ([134.134.136.20]:39625 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756607AbbEVRHZ (ORCPT ); Fri, 22 May 2015 13:07:25 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,476,1427785200"; d="scan'208";a="714346511" Date: Fri, 22 May 2015 17:07:22 +0000 (UTC) From: Keith Busch X-X-Sender: vmware@localhost.lm.intel.com To: Parav Pandit cc: Keith Busch , linux-nvme@lists.infradead.org, Matthew Wilcox , Jens Axboe , linux-kernel@vger.kernel.org Subject: Re: [PATCH] NVMe: Avoid interrupt disable during queue init. In-Reply-To: Message-ID: References: <1432253553-17045-1-git-send-email-parav.pandit@avagotech.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) 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: 895 Lines: 17 On Fri, 22 May 2015, Parav Pandit wrote: > On Fri, May 22, 2015 at 9:53 PM, Keith Busch wrote: >> A memory barrier before incrementing the dev->queue_count (and assigning >> the pointer in the array before that) should address this concern. > > Sure. mb() will solve the publisher side problem. RCU is wrapper around mb(). > However mb() doesn't solve the issue of q_lock variable getting > fetched before if (!nvmeq) condition being executed, by value > compilation optimizations in nvme_kthread(). Eh? The value of dev->queue_count prevents the thread's for-loop from iterating that nvmeq before the q_lock is initialized. -- 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/