Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756597Ab3DPMG3 (ORCPT ); Tue, 16 Apr 2013 08:06:29 -0400 Received: from terminus.zytor.com ([198.137.202.10]:40628 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752195Ab3DPMG2 (ORCPT ); Tue, 16 Apr 2013 08:06:28 -0400 User-Agent: K-9 Mail for Android In-Reply-To: <20130416100439.GM3672@sgi.com> References: <20130416095641.GL3658@sgi.com> <20130416100439.GM3672@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [Patch -v4 4/4] Make reboot_cpuid a kernel parameter. other cpus. From: "H. Peter Anvin" Date: Tue, 16 Apr 2013 05:05:45 -0700 To: Robin Holt , Ingo Molnar , Russ Anderson CC: Shawn Guo , Oleg Nesterov , Andrew Morton , Joe Perches , 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 Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5833 Lines: 174 Why not just support the existing syntax everywhere? Robin Holt wrote: >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 > >--- > >Changes since -v3 >- Added a reboot=s#### compatibility mode for x86. > > Documentation/kernel-parameters.txt | 2 ++ >arch/x86/kernel/reboot.c | 39 >+++++++++++++------------------------ > kernel/reboot.c | 8 +++++++- > 3 files changed, 22 insertions(+), 27 deletions(-) > >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 8cfef20..b2ef798 100644 >--- a/kernel/reboot.c >+++ b/kernel/reboot.c >@@ -10,6 +10,7 @@ > #include > #include > #include >+#include > #include > #include > #include >@@ -69,13 +70,18 @@ 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. */ -- Sent from my mobile phone. 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