Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754982Ab1FUJIp (ORCPT ); Tue, 21 Jun 2011 05:08:45 -0400 Received: from na3sys009aog101.obsmtp.com ([74.125.149.67]:49441 "EHLO na3sys009aog101.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752727Ab1FUJIn (ORCPT ); Tue, 21 Jun 2011 05:08:43 -0400 Message-ID: <4E005F92.8030208@ti.com> Date: Tue, 21 Jun 2011 14:38:34 +0530 From: Santosh Shilimkar User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 MIME-Version: 1.0 To: Russell King - ARM Linux CC: Peter Zijlstra , Thomas Gleixner , linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH] ARM: smp: Fix the CPU hotplug race with scheduler. References: <1308561839-18407-1-git-send-email-santosh.shilimkar@ti.com> <20110620095053.GA2082@n2100.arm.linux.org.uk> <20110620101438.GD2082@n2100.arm.linux.org.uk> <4DFF20B3.7010209@ti.com> <20110620104415.GF2082@n2100.arm.linux.org.uk> <4DFF255E.5030308@ti.com> <20110620111336.GG2082@n2100.arm.linux.org.uk> <4DFF2E37.8030602@ti.com> <20110620114019.GH2082@n2100.arm.linux.org.uk> <20110620142338.GL2082@n2100.arm.linux.org.uk> <4DFF5F29.2000904@ti.com> In-Reply-To: <4DFF5F29.2000904@ti.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1549 Lines: 42 Russell, On 6/20/2011 8:24 PM, Santosh Shilimkar wrote: > On 6/20/2011 7:53 PM, Russell King - ARM Linux wrote: >> On Mon, Jun 20, 2011 at 12:40:19PM +0100, Russell King - ARM Linux wrote: [....] >> So, as loops_per_jiffy is not local to this function, the compiler has >> to write out that zero value, before calling calibrate_delay_converge(), >> and loops_per_jiffy only becomes non-zero _after_ >> calibrate_delay_converge() >> has returned. This opens the window and allows the spinlock debugging >> code to explode. >> >> This patch closes the window completely, by only writing to >> loops_per_jiffy >> only when we have a real value for it. >> >> This allows me to boot 3.0.0-rc3 on Versatile Express (4 CPU) whereas >> without this it fails with spinlock lockup and rcu problems. >> >> init/calibrate.c | 14 ++++++++------ >> 1 files changed, 8 insertions(+), 6 deletions(-) >> > I am away from my board now. Will test this change. Have tested your change and it seems to fix the crash I was observing. Are you planning to send this fix for rc5? > btw, the online-active race is still open even with this patch close > and should be fixed. > The only problem remains is waiting for active mask before marking CPU online. Shall I refresh my patch with only this change then ? Regards Santosh -- 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/