From d04f41e35343f1d788551fd3f753f51794f4afcf Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 7 Mar 2007 18:12:31 +0100 Subject: [PATCH] [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 Signed-off-by: Ingo Molnar Signed-off-by: Linus Torvalds --- arch/i386/kernel/smpboot.c | 16 ++++++++++------ arch/x86_64/kernel/smpboot.c | 5 ++++- 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c index 9b0dd2744c82..4ff55e675576 100644 --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include @@ -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) diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c index 35443729aad8..cd4643a37022 100644 --- a/arch/x86_64/kernel/smpboot.c +++ b/arch/x86_64/kernel/smpboot.c @@ -923,8 +923,9 @@ void __init smp_prepare_boot_cpu(void) */ int __cpuinit __cpu_up(unsigned int cpu) { - int err; int apicid = cpu_present_to_apicid(cpu); + unsigned long flags; + int err; WARN_ON(irqs_disabled()); @@ -958,7 +959,9 @@ int __cpuinit __cpu_up(unsigned int cpu) /* * Make sure and check TSC sync: */ + local_irq_save(flags); check_tsc_sync_source(cpu); + local_irq_restore(flags); while (!cpu_isset(cpu, cpu_online_map)) cpu_relax(); -- 2.20.1