On 04/12/2013 03:01 PM, Robin Holt wrote:
> kernel/sys.c | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 0da73cf..4d1047d 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -357,6 +357,19 @@ int unregister_reboot_notifier(struct notifier_block *nb)
> }
> EXPORT_SYMBOL(unregister_reboot_notifier);
>
> +void migrate_to_boot_cpu(void)
> +{
> + /* The boot cpu is always logical cpu 0 */
> + int reboot_cpu_id = 0;
> +
> + /* Make certain the cpu I'm about to reboot on is online */
> + if (!cpu_online(reboot_cpu_id))
> + reboot_cpu_id = smp_processor_id();
> +
If CPU 0 is offline, there is no point in binding, right?
[Fenghua (in CC) added the support to offline CPU0 on x86 Intel platforms.
So its possible that CPU0 is offline when you try a reboot.]
> + /* Make certain I only run on the appropriate processor */
> + set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id));
> +}
> +
> /**
> * kernel_restart - reboot the system
> * @cmd: pointer to buffer containing command to execute for restart
> @@ -368,7 +381,7 @@ EXPORT_SYMBOL(unregister_reboot_notifier);
> void kernel_restart(char *cmd)
> {
> kernel_restart_prepare(cmd);
> - disable_nonboot_cpus();
> + migrate_to_boot_cpu();
> syscore_shutdown();
> if (!cmd)
> printk(KERN_EMERG "Restarting system.\n");
> @@ -414,7 +427,7 @@ 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_boot_cpu();
Okay, so you are touching poweroff also. Restart was only recently altered
by Shawn, so we can assume that his fix was necessary only to his platform.
However, for poweroff, I see the commit below in the git log, which added
the disable_nonboot_cpus() call.
commit 4047727e5ae33f9b8d2b7766d1994ea6e5ec2991
Author: Mark Lord <l...@rtr.ca>
Date: Mon Oct 1 01:20:10 2007 -0700
Fix SMP poweroff hangs
Its an old commit, so perhaps the issue no longer holds good, but I thought
I should bring this to notice, just in case.
> syscore_shutdown();
> printk(KERN_EMERG "Power down.\n");
> kmsg_dump(KMSG_DUMP_POWEROFF);
>
Regards,
Srivatsa S. Bhat
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