Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759164Ab1FQOkN (ORCPT ); Fri, 17 Jun 2011 10:40:13 -0400 Received: from s15228384.onlinehome-server.info ([87.106.30.177]:51898 "EHLO mail.x86-64.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754589Ab1FQOkK (ORCPT ); Fri, 17 Jun 2011 10:40:10 -0400 Date: Fri, 17 Jun 2011 16:39:48 +0200 From: Borislav Petkov To: Hidetoshi Seto Cc: "linux-kernel@vger.kernel.org" , "x86@kernel.org" , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , "Luck, Tony" Subject: Re: [PATCH 2/8] x86, mce: remove redundant mce_available() checks Message-ID: <20110617143947.GH18054@aftab> References: <4DFB1242.90404@jp.fujitsu.com> <4DFB1359.9000204@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DFB1359.9000204@jp.fujitsu.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6279 Lines: 202 On Fri, Jun 17, 2011 at 04:42:01AM -0400, Hidetoshi Seto wrote: > I noticed that there is no need to check mce_available() on runtime. > In fact we don't support asymmetric configuration such as mixture of > varied processors which some are MCE capable while others are not. simplify the above sentence please. > > Finally only 2 checks in init code path are enough for now. > > When !mce_available(): > - in mcheck_cpu_init(): > - mce timer is not initialized ... in __mcheck_cpu_init_timer() > - cmci is not enabled > - and later in mce_init_device(): > - sysfs files are not created > - hotplug notifier is not registered > So we don't need checks at all in these functions which is never s/which is/because they are/ > called when !mce_available(). > > For safety I also add a warning which is given when bad unsupported > asymmetric configuration is detected. > > Signed-off-by: Hidetoshi Seto > --- > arch/x86/include/asm/mce.h | 2 - > arch/x86/kernel/cpu/mcheck/mce.c | 34 ++++++++++--------------------- > arch/x86/kernel/cpu/mcheck/mce_intel.c | 2 +- > 3 files changed, 12 insertions(+), 26 deletions(-) > > diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h > index 716b48a..77825dd 100644 > --- a/arch/x86/include/asm/mce.h > +++ b/arch/x86/include/asm/mce.h > @@ -180,8 +180,6 @@ void mce_amd_feature_init(struct cpuinfo_x86 *c); > static inline void mce_amd_feature_init(struct cpuinfo_x86 *c) { } > #endif > > -int mce_available(struct cpuinfo_x86 *c); > - > DECLARE_PER_CPU(unsigned, mce_exception_count); > DECLARE_PER_CPU(unsigned, mce_poll_count); > > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c > index 42fc8d2..205b334 100644 > --- a/arch/x86/kernel/cpu/mcheck/mce.c > +++ b/arch/x86/kernel/cpu/mcheck/mce.c > @@ -449,7 +449,7 @@ static int mce_ring_add(unsigned long pfn) > return 0; > } > > -int mce_available(struct cpuinfo_x86 *c) > +static int mce_available(struct cpuinfo_x86 *c) > { > if (mce_disabled) > return 0; > @@ -1121,10 +1121,7 @@ static void mce_start_timer(unsigned long data) > > WARN_ON(smp_processor_id() != data); > > - if (mce_available(__this_cpu_ptr(&cpu_info))) { > - machine_check_poll(MCP_TIMESTAMP, > - &__get_cpu_var(mce_poll_banks)); > - } > + machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_poll_banks)); > > /* > * Alert userspace if needed. If we logged an MCE, reduce the > @@ -1146,8 +1143,7 @@ static void mce_timer_delete_all(void) > int cpu; > > for_each_online_cpu(cpu) { > - if (mce_available(&per_cpu(cpu_info, cpu))) > - del_timer_sync(&per_cpu(mce_timer, cpu)); > + del_timer_sync(&per_cpu(mce_timer, cpu)); > } no need for the parentheses but this should be part of the first patch anyway. > } > > @@ -1418,8 +1414,15 @@ void __cpuinit mcheck_cpu_init(struct cpuinfo_x86 *c) > if (__mcheck_cpu_ancient_init(c)) > return; > > - if (!mce_available(c)) > + if (!mce_available(c)) { > + /* > + * Asymmetric configurations are not supported today. > + * If mce_banks is allocated there must be a cpu passed here. > + */ > + WARN_ON(!mce_disabled && mce_banks); > + mce_disabled = 1; > return; > + } I don't think this will ever happen so why complicate the code needlessly? This can only be executed if at least one of the cores on the system has CPUID(1)_EDX, bits 7 and 14 cleared and that's just silly. Besides, mcheck_init_device() already confirms we don't support MCE-asymmetric configs: if (!mce_available(&boot_cpu_data)) return -EIO; > if (__mcheck_cpu_cap_init() < 0 || __mcheck_cpu_apply_quirks(c) < 0) { > mce_disabled = 1; > @@ -1761,8 +1764,6 @@ static struct syscore_ops mce_syscore_ops = { > > static void mce_cpu_restart(void *data) > { > - if (!mce_available(__this_cpu_ptr(&cpu_info))) > - return; > __mcheck_cpu_init_generic(); > __mcheck_cpu_init_timer(); > } > @@ -1777,15 +1778,11 @@ static void mce_restart(void) > /* Toggle features for corrected errors */ > static void mce_disable_cmci(void *data) > { > - if (!mce_available(__this_cpu_ptr(&cpu_info))) > - return; > cmci_clear(); > } > > static void mce_enable_ce(void *all) > { > - if (!mce_available(__this_cpu_ptr(&cpu_info))) > - return; > cmci_reenable(); > cmci_recheck(); > if (all) > @@ -1946,9 +1943,6 @@ static __cpuinit int mce_sysdev_create(unsigned int cpu) > int err; > int i, j; > > - if (!mce_available(&boot_cpu_data)) > - return -EIO; > - > memset(&sysdev->kobj, 0, sizeof(struct kobject)); > sysdev->id = cpu; > sysdev->cls = &mce_sysdev_class; > @@ -2006,9 +2000,6 @@ static void __cpuinit mce_disable_cpu(void *h) > unsigned long action = *(unsigned long *)h; > int i; > > - if (!mce_available(__this_cpu_ptr(&cpu_info))) > - return; > - > if (!(action & CPU_TASKS_FROZEN)) > cmci_clear(); > for (i = 0; i < banks; i++) { > @@ -2024,9 +2015,6 @@ static void __cpuinit mce_reenable_cpu(void *h) > unsigned long action = *(unsigned long *)h; > int i; > > - if (!mce_available(__this_cpu_ptr(&cpu_info))) > - return; > - > if (!(action & CPU_TASKS_FROZEN)) > cmci_reenable(); > for (i = 0; i < banks; i++) { > diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c > index 8694ef5..393516c 100644 > --- a/arch/x86/kernel/cpu/mcheck/mce_intel.c > +++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c > @@ -130,7 +130,7 @@ void cmci_recheck(void) > unsigned long flags; > int banks; > > - if (!mce_available(__this_cpu_ptr(&cpu_info)) || !cmci_supported(&banks)) > + if (!cmci_supported(&banks)) > return; > local_irq_save(flags); > machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned)); > -- > 1.7.1 > > > -- Regards/Gruss, Boris. Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach GM: Alberto Bozzo Reg: Dornach, Landkreis Muenchen HRB Nr. 43632 WEEE Registernr: 129 19551 -- 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/