Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934640Ab3DOSXD (ORCPT ); Mon, 15 Apr 2013 14:23:03 -0400 Received: from relay1.sgi.com ([192.48.179.29]:38760 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753635Ab3DOSXB (ORCPT ); Mon, 15 Apr 2013 14:23:01 -0400 Date: Mon, 15 Apr 2013 13:22:59 -0500 From: Robin Holt To: "H. Peter Anvin" Cc: Robin Holt , Ingo Molnar , Russ Anderson , Shawn Guo , Oleg Nesterov , Andrew Morton , Lai Jiangshan , Linus Torvalds , Linux Kernel Mailing List , Michel Lespinasse , "Paul E. McKenney" , Paul Mackerras , Peter Zijlstra , "rusty@rustcorp.com.au" , Tejun Heo , the arch/x86 maintainers , Thomas Gleixner Subject: Re: [Patch -v3 4/4] Make reboot_cpuid a kernel parameter. Message-ID: <20130415182258.GE3658@sgi.com> References: <20130415171225.GC3658@sgi.com> <20130415171635.GI3672@sgi.com> <71f0c948-cdea-4e8e-86a3-088d306388b9@email.android.com> <20130415173324.GD3658@sgi.com> <0d5a866d-3d40-4592-bb9d-d938fb3312e2@email.android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0d5a866d-3d40-4592-bb9d-d938fb3312e2@email.android.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: 6009 Lines: 170 On Mon, Apr 15, 2013 at 10:47:49AM -0700, H. Peter Anvin wrote: > We usually don't break working user setups as a matter if policy. Only if it can't be avoided. > > Robin Holt wrote: > > >On Mon, Apr 15, 2013 at 10:18:31AM -0700, H. Peter Anvin wrote: > >> Um... doesn't this break anyone who currently depends on this? > > > >Yes. That is also why I kept this separate and not tagged for > >stable. They would need to start using the more general kernel > >parameter > >to get the same functionality. Should I have done it differently? How about: Author: Robin Holt Date: Mon Apr 15 11:39:33 2013 -0500 Make reboot_cpuid a kernel parameter. Moving the reboot=s<##> parameter for x86 to a kernel parameter proper. I did not find any other arch that was specifying the reboot cpu. I left a compatibility mode in there. The new parameter always takes precedence. I also fixed up the current code to support up to cpuid's up to the current max of 4096. Signed-off-by: Robin Holt To: Ingo Molnar To: Russ Anderson Cc: Shawn Guo Cc: Oleg Nesterov Cc: Andrew Morton Cc: "H. Peter Anvin" Cc: Lai Jiangshan Cc: Linus Torvalds Cc: Linux Kernel Mailing List Cc: Michel Lespinasse Cc: Oleg Nesterov Cc: "Paul E. McKenney" Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Robin Holt Cc: "rusty@rustcorp.com.au" Cc: Tejun Heo Cc: the arch/x86 maintainers Cc: Thomas Gleixner diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4609e81..11ebb48 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2597,6 +2597,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: [,[,...]] See arch/*/kernel/reboot.c or arch/*/kernel/process.c + reboot_cpuid= [KNL] cpuid to use for reboot/halt, etc operations. + relax_domain_level= [KNL, SMP] Set scheduler's default relax_domain_level. See Documentation/cgroups/cpusets.txt. diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 76fa1e9..cdcf28f 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -49,10 +49,6 @@ int reboot_force; */ static int reboot_default = 1; -#ifdef CONFIG_SMP -static int reboot_cpu = -1; -#endif - /* * This is set if we need to go through the 'emergency' path. * When machine_emergency_restart() is called, we may be on @@ -63,6 +59,8 @@ static int reboot_emergency; /* This is set by the PCI code if either type 1 or type 2 PCI is detected */ bool port_cf9_safe = false; +extern int reboot_cpuid; + /* * reboot=b[ios] | s[mp] | t[riple] | k[bd] | e[fi] [, [w]arm | [c]old] | p[ci] * warm Don't set the cold reboot flag @@ -97,10 +95,14 @@ static int __init reboot_setup(char *str) #ifdef CONFIG_SMP case 's': - if (isdigit(*(str+1))) { - reboot_cpu = (int) (*(str+1) - '0'); - if (isdigit(*(str+2))) - reboot_cpu = reboot_cpu*10 + (int)(*(str+2) - '0'); + if (reboot_cpuid < 0) { + int coffset; + + reboot_cpuid = 0; + for (coffset = 1; isdigit(*(str + coffset)); coffset++) { + reboot_cpuid *= 10; + reboot_cpuid += (int)(*(str+2) - '0'); + } } /* * We will leave sorting out the final value @@ -615,25 +617,10 @@ void native_machine_shutdown(void) /* Stop the cpus and apics */ #ifdef CONFIG_SMP - /* The boot cpu is always logical cpu 0 */ - int reboot_cpu_id = 0; - - /* See if there has been given a command line override */ - if ((reboot_cpu != -1) && (reboot_cpu < nr_cpu_ids) && - cpu_online(reboot_cpu)) - reboot_cpu_id = reboot_cpu; - - /* Make certain the cpu I'm about to reboot on is online */ - if (!cpu_online(reboot_cpu_id)) - reboot_cpu_id = smp_processor_id(); - - /* Make certain I only run on the appropriate processor */ - set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id)); - /* - * O.K Now that I'm on the appropriate processor, stop all of the - * others. Also disable the local irq to not receive the per-cpu - * timer interrupt which may trigger scheduler's load balance. + * Stop all of the others. Also disable the local irq to + * not receive the per-cpu timer interrupt which may trigger + * scheduler's load balance. */ local_irq_disable(); stop_other_cpus(); diff --git a/kernel/reboot.c b/kernel/reboot.c index 187a0d8..8d7b7d4 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -66,13 +67,18 @@ int unregister_reboot_notifier(struct notifier_block *nb) } EXPORT_SYMBOL(unregister_reboot_notifier); +int reboot_cpuid = -1; +core_param(reboot_cpuid, reboot_cpuid, int, 0644); + void migrate_to_reboot_cpu(void) { /* The boot cpu is always logical cpu 0 */ - int reboot_cpu_id = 0; + int reboot_cpu_id = reboot_cpuid; /* Make certain the cpu I'm about to reboot on is online */ if (!cpu_online(reboot_cpu_id)) + reboot_cpu_id = 0; + if (!cpu_online(reboot_cpu_id)) reboot_cpu_id = smp_processor_id(); /* Prevent races with other tasks migrating this task. */ -- 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/