Messages in this thread Patch in this message | | | Date | Wed, 15 Feb 2012 22:14:41 -0500 | From | Don Zickus <> | Subject | Re: [PATCH 2/2] x86, reschedule: check to see if system is shutting down |
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On Wed, Feb 15, 2012 at 06:59:47PM +0100, Peter Zijlstra wrote: > > > The only way is to unplug all cpus except the one. Problem with that is > > > that we cannot (as of yet) unplug the boot cpu. > > > > Yeah, well we can migrate to the boot cpu. I think powerpc does that for > > kdump. > > Right, there's that.
Well we are in luck, migrating to cpu0 is already done in the shutdown path.
arch/x86/kernel/reboot.c::native_machine_shutdown:662 set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id));
Now most of the time it seems to be cpu0, but I guess corner cases can put it elsewhere. I replaced 'stop_other_cpus' with 'for_each_online_cpu(cpu) { cpu_down(cpu) }. And things seemed to work. Output below, patch below that:
===================== Please stand by while rebooting the system... [ 101.470240] md: stopping all md devices. [ 101.474346] kvm: exiting hardware virtualization [ 101.480071] sd 3:0:0:0: [sdb] Synchronizing SCSI cache [ 101.535977] sd 0:0:0:0: [sda] Synchronizing SCSI cache [ 101.643479] Restarting system. [ 101.646624] machine restart [ 101.649501] DONDON: on cpu2 [ 101.652502] DONDON: on new cpu0 [ 101.658397] Broke affinity for irq 42 [ 101.662168] Broke affinity for irq 47 [ 101.669281] bnx2fc: CPU 1 offline: Remove Rx thread [ 101.674381] CPU 1 offline: Remove Rx thread [ 101.680595] Broke affinity for irq 22 [ 101.686510] bnx2fc: CPU 2 offline: Remove Rx thread [ 101.691569] CPU 2 offline: Remove Rx thread [ 101.697260] Broke affinity for irq 16 [ 101.702057] lockdep: fixing up alternatives. [ 101.706476] SMP alternatives: switching to UP code [ 101.720162] bnx2fc: CPU 3 offline: Remove Rx thread [ 101.725206] CPU 3 offline: Remove Rx thread ====================
Does that work for you?
Cheers, Don
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index d840e69..c3569ac 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -644,6 +644,7 @@ void native_machine_shutdown(void) /* The boot cpu is always logical cpu 0 */ int reboot_cpu_id = 0; + int cpu; #ifdef CONFIG_X86_32 /* See if there has been given a command line override */ @@ -652,17 +653,24 @@ void native_machine_shutdown(void) reboot_cpu_id = reboot_cpu; #endif + printk("DONDON: on cpu%d\n", smp_processor_id()); /* 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)); + printk("DONDON: on new cpu%d\n", smp_processor_id()); /* O.K Now that I'm on the appropriate processor, * stop all of the others. */ - stop_other_cpus(); + //stop_other_cpus(); + for_each_online_cpu(cpu) { + if (cpu == 0) + continue; + cpu_down(cpu); + } #endif lapic_shutdown();
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