x86: Fix irq0 / local apic timer accounting

The clock events merge introduced a change to the nmi watchdog code to
handle the not longer increasing local apic timer count in the
broadcast mode. This is fine for UP, but on SMP it pampers over a
stuck CPU which is not handling the broadcast interrupt due to the
unconditional sum up of local apic timer count and irq0 count.

To cover all cases we need to keep track on which CPU irq0 is
handled. In theory this is CPU#0 due to the explicit disabling of irq
balancing for irq0, but there are systems which ignore this on the
hardware level. The per cpu irq0 accounting allows us to remove the
irq0 to CPU0 binding as well.

Add a per cpu counter for irq0 and evaluate this instead of the global
irq0 count in the nmi watchdog code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

diff --git a/arch/x86/kernel/nmi_64.c b/arch/x86/kernel/nmi_64.c
index 0ec6d2ddb931f48a2cbeef6daf09503907328638..e60ac0da528393751dc466eb1fbbe623713d6f97 100644 (file)
--- a/arch/x86/kernel/nmi_64.c
+++ b/arch/x86/kernel/nmi_64.c
@@ -329,7 +329,7 @@ int __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
                touched = 1;
        }
 
-       sum = read_pda(apic_timer_irqs);
+       sum = read_pda(apic_timer_irqs) + read_pda(irq0_irqs);
        if (__get_cpu_var(nmi_touch)) {
                __get_cpu_var(nmi_touch) = 0;
                touched = 1;

diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c
index 7781df1d50e3db2067198b994c95a02126d9bb64..16f58886e8dc4010dbe84624a0434c0d36f428e2 100644 (file)
--- a/arch/x86/kernel/time_64.c
+++ b/arch/x86/kernel/time_64.c
@@ -194,6 +194,8 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id)
 
 static irqreturn_t timer_event_interrupt(int irq, void *dev_id)
 {
+       add_pda(irq0_irqs, 1);
+
        global_clock_event->event_handler(global_clock_event);
 
        return IRQ_HANDLED;

diff --git a/include/asm-x86/pda.h b/include/asm-x86/pda.h
index 5642634843c472921ec08802fda4f36ca6a0ce1b..fb49f80eb94f9f03929392f058e4669ca5eb6968 100644 (file)
--- a/include/asm-x86/pda.h
+++ b/include/asm-x86/pda.h
@@ -29,6 +29,7 @@ struct x8664_pda {
        short isidle;
        struct mm_struct *active_mm;
        unsigned apic_timer_irqs;
+       unsigned irq0_irqs;
 } ____cacheline_aligned_in_smp;
 
 extern struct x8664_pda *_cpu_pda[];