diff options
| author | Ingo Molnar <mingo@elte.hu> | 2007-03-07 18:12:31 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-03-07 10:07:24 -0800 |
| commit | d04f41e35343f1d788551fd3f753f51794f4afcf (patch) | |
| tree | 50f22b1deab312476254868e8ec8c0c592c3d3e0 /arch/i386/kernel | |
| parent | 08e15e81a40e3241ce93b4a43886f3abda184aa6 (diff) | |
[PATCH] CPU hotplug: call check_tsc_sync_source() with irqs off
check_tsc_sync_source() depends on being called with irqs disabled (it
checks whether the TSC is coherent across two specific CPUs). This is
incidentally true during bootup, but not during cpu hotplug __cpu_up().
This got found via smp_processor_id() debugging.
disable irqs explicitly and remove the unconditional enabling of
interrupts. Add touch_nmi_watchdog() to the cpu_online_map busy loop.
this bug is present both on i386 and on x86_64.
Reported-by: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/i386/kernel')
| -rw-r--r-- | arch/i386/kernel/smpboot.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c index 9b0dd2744c8..4ff55e67557 100644 --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -45,6 +45,7 @@ #include <linux/notifier.h> #include <linux/cpu.h> #include <linux/percpu.h> +#include <linux/nmi.h> #include <linux/delay.h> #include <linux/mc146818rtc.h> @@ -1278,8 +1279,9 @@ void __cpu_die(unsigned int cpu) int __cpuinit __cpu_up(unsigned int cpu) { + unsigned long flags; #ifdef CONFIG_HOTPLUG_CPU - int ret=0; + int ret = 0; /* * We do warm boot only on cpus that had booted earlier @@ -1297,23 +1299,25 @@ int __cpuinit __cpu_up(unsigned int cpu) /* In case one didn't come up */ if (!cpu_isset(cpu, cpu_callin_map)) { printk(KERN_DEBUG "skipping cpu%d, didn't come online\n", cpu); - local_irq_enable(); return -EIO; } - local_irq_enable(); - per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; /* Unleash the CPU! */ cpu_set(cpu, smp_commenced_mask); /* - * Check TSC synchronization with the AP: + * Check TSC synchronization with the AP (keep irqs disabled + * while doing so): */ + local_irq_save(flags); check_tsc_sync_source(cpu); + local_irq_restore(flags); - while (!cpu_isset(cpu, cpu_online_map)) + while (!cpu_isset(cpu, cpu_online_map)) { cpu_relax(); + touch_nmi_watchdog(); + } #ifdef CONFIG_X86_GENERICARCH if (num_online_cpus() > 8 && genapic == &apic_default) |