From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754448Ab1ACMEK (ORCPT ); Mon, 3 Jan 2011 07:04:10 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:56846 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753995Ab1ACMEI (ORCPT ); Mon, 3 Jan 2011 07:04:08 -0500 Date: Mon, 3 Jan 2011 13:03:10 +0100 From: Ingo Molnar To: Robert Richter Cc: "linux-kernel@vger.kernel.org" , "oprofile-list@lists.sourceforge.net" , Peter Zijlstra , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , atswartz@gmail.com, "Rafael J. Wysocki" , Dan Carpenter , Andrew Morton , stable@kernel.org Subject: Re: [PATCH] arch/x86/oprofile/op_model_amd.c: perform initialisation on a single CPU Message-ID: <20110103120310.GA23927@elte.hu> References: <20101230173847.GA2734@elte.hu> <20110103111514.GM4739@erda.amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110103111514.GM4739@erda.amd.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Robert Richter wrote: > static void init_ibs(void) > { > ibs_caps = get_ibs_caps(); this get_ibs_caps() call is percpu too - still it now runs with preempt off. > + printk(KERN_INFO "oprofile: AMD IBS detected (0x%08x)\n", > + (unsigned)ibs_caps); that cast looks ugly and unnecessary. I fixed both in the commit below. (not tested yet) Thanks, Ingo ---------------> >>From c7c25802b39c443b3745cfa973dc49a97a3491f8 Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Mon, 3 Jan 2011 12:15:14 +0100 Subject: [PATCH] arch/x86/oprofile/op_model_amd.c: Perform initialisation on a single CPU Disable preemption in init_ibs(). The function only checks the ibs capabilities and sets up pci devices (if necessary). It runs only on one cpu but operates with the local APIC and some MSRs, thus it is better to disable preemption. [ 7.034377] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/483 [ 7.034385] caller is setup_APIC_eilvt+0x155/0x180 [ 7.034389] Pid: 483, comm: modprobe Not tainted 2.6.37-rc1-20101110+ #1 [ 7.034392] Call Trace: [ 7.034400] [] debug_smp_processor_id+0xd2/0xf0 [ 7.034404] [] setup_APIC_eilvt+0x155/0x180 [ ... ] Addresses https://bugzilla.kernel.org/show_bug.cgi?id=22812 Reported-by: Signed-off-by: Robert Richter Cc: oprofile-list@lists.sourceforge.net Cc: Peter Zijlstra Cc: Frederic Weisbecker Cc: Rafael J. Wysocki Cc: Dan Carpenter Cc: Andrew Morton Cc: [2.6.37.x] LKML-Reference: <20110103111514.GM4739@erda.amd.com> [ small cleanups ] Signed-off-by: Ingo Molnar --- arch/x86/oprofile/op_model_amd.c | 24 ++++++++++++++++-------- 1 files changed, 16 insertions(+), 8 deletions(-) diff --git a/arch/x86/oprofile/op_model_amd.c b/arch/x86/oprofile/op_model_amd.c index a011bcc..7d90d47 100644 --- a/arch/x86/oprofile/op_model_amd.c +++ b/arch/x86/oprofile/op_model_amd.c @@ -630,21 +630,29 @@ static int __init_ibs_nmi(void) return 0; } -/* initialize the APIC for the IBS interrupts if available */ +/* + * check and reserve APIC extended interrupt LVT offset for IBS if + * available + * + * init_ibs() preforms implicitly cpu-local operations, so pin this + * thread to its current CPU + */ + static void init_ibs(void) { - ibs_caps = get_ibs_caps(); + preempt_disable(); + ibs_caps = get_ibs_caps(); if (!ibs_caps) - return; + goto out; - if (__init_ibs_nmi()) { + if (__init_ibs_nmi() < 0) ibs_caps = 0; - return; - } + else + printk(KERN_INFO "oprofile: AMD IBS detected (0x%08x)\n", ibs_caps); - printk(KERN_INFO "oprofile: AMD IBS detected (0x%08x)\n", - (unsigned)ibs_caps); +out: + preempt_enable(); } static int (*create_arch_files)(struct super_block *sb, struct dentry *root);