[merged] migrate-shutdown-reboot-to-boot-cpu.patch removed from -mm tree

[merged] migrate-shutdown-reboot-to-boot-cpu.patch removed from -mm tree

[akpm]

Subject: [merged] migrate-shutdown-reboot-to-boot-cpu.patch removed from -mm tree
To: holt@sgi.com,gxt@mprc.pku.edu.cn,hpa@zytor.com,linux@arm.linux.org.uk,mingo@elte.hu,rja@sgi.com,shawn.guo@linaro.org,srivatsa.bhat@linux.vnet.ibm.com,stable@vger.kernel.org,tglx@linutronix.de,mm-commits@vger.kernel.org
From: akpm@linux-foundation.org
Date: Thu, 13 Jun 2013 11:57:25 -0700


The patch titled
     Subject: reboot: rigrate shutdown/reboot to boot cpu
has been removed from the -mm tree.  Its filename was
     migrate-shutdown-reboot-to-boot-cpu.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Robin Holt <holt@sgi.com>
Subject: reboot: rigrate shutdown/reboot to boot cpu

We recently noticed that reboot of a 1024 cpu machine takes approx 16
minutes of just stopping the cpus.  The slowdown was tracked to commit
f96972f ("kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()").

The current implementation does all the work of hot removing the cpus
before halting the system.  We are switching to just migrating to the
boot cpu and then continuing with shutdown/reboot.

This also has the effect of not breaking x86's command line parameter for
specifying the reboot cpu.  Note, this code was shamelessly copied from
arch/x86/kernel/reboot.c with bits removed pertaining to the reboot_cpu
command line parameter.

Signed-off-by: Robin Holt <holt@sgi.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/sys.c |   29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff -puN kernel/sys.c~migrate-shutdown-reboot-to-boot-cpu kernel/sys.c
--- a/kernel/sys.c~migrate-shutdown-reboot-to-boot-cpu
+++ a/kernel/sys.c
@@ -362,6 +362,29 @@ int unregister_reboot_notifier(struct no
 }
 EXPORT_SYMBOL(unregister_reboot_notifier);
 
+/* Add backwards compatibility for stable trees. */
+#ifndef PF_NO_SETAFFINITY
+#define PF_NO_SETAFFINITY		PF_THREAD_BOUND
+#endif
+
+static void migrate_to_reboot_cpu(void)
+{
+	/* The boot cpu is always logical cpu 0 */
+	int cpu = 0;
+
+	cpu_hotplug_disable();
+
+	/* Make certain the cpu I'm about to reboot on is online */
+	if (!cpu_online(cpu))
+		cpu = cpumask_first(cpu_online_mask);
+
+	/* Prevent races with other tasks migrating this task */
+	current->flags |= PF_NO_SETAFFINITY;
+
+	/* Make certain I only run on the appropriate processor */
+	set_cpus_allowed_ptr(current, cpumask_of(cpu));
+}
+
 /**
  *	kernel_restart - reboot the system
  *	@cmd: pointer to buffer containing command to execute for restart
@@ -373,7 +396,7 @@ EXPORT_SYMBOL(unregister_reboot_notifier
 void kernel_restart(char *cmd)
 {
 	kernel_restart_prepare(cmd);
-	disable_nonboot_cpus();
+	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	if (!cmd)
 		printk(KERN_EMERG "Restarting system.\n");
@@ -400,7 +423,7 @@ static void kernel_shutdown_prepare(enum
 void kernel_halt(void)
 {
 	kernel_shutdown_prepare(SYSTEM_HALT);
-	disable_nonboot_cpus();
+	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	printk(KERN_EMERG "System halted.\n");
 	kmsg_dump(KMSG_DUMP_HALT);
@@ -419,7 +442,7 @@ void kernel_power_off(void)
 	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
 	if (pm_power_off_prepare)
 		pm_power_off_prepare();
-	disable_nonboot_cpus();
+	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	printk(KERN_EMERG "Power down.\n");
 	kmsg_dump(KMSG_DUMP_POWEROFF);
_

Patches currently in -mm which might be from holt@sgi.com are

origin.patch
dump_stack-serialize-the-output-from-dump_stack.patch
dump_stack-serialize-the-output-from-dump_stack-fix.patch
panic-add-cpu-pid-to-warn_slowpath_common-in-warning-printks.patch
drivers-misc-sgi-gru-grufaultc-fix-a-sanity-test-in-gru_set_context_option.patch
reboot-remove-stable-friendly-pf_thread_bound-define.patch
reboot-move-shutdown-reboot-related-functions-to-kernel-rebootc.patch
reboot-checkpatchpl-the-new-kernel-rebootc-file.patch
reboot-x86-prepare-reboot_mode-for-moving-to-generic-kernel-code.patch
reboot-unicore32-prepare-reboot_mode-for-moving-to-generic-kernel-code.patch
reboot-arm-remove-unused-restart_mode-fields-from-some-arm-subarchs.patch
reboot-arm-prepare-reboot_mode-for-moving-to-generic-kernel-code.patch
reboot-arm-change-reboot_mode-to-use-enum-reboot_mode.patch
reboot-arm-change-reboot_mode-to-use-enum-reboot_mode-fix.patch
reboot-move-arch-x86-reboot=-handling-to-generic-kernel.patch