nmi_lock must be a spinning spinlock in -rt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
 
        /* We can be called before check_nmi_watchdog, hence NULL check. */
        if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
-               static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
+               static DEFINE_RAW_SPINLOCK(lock); /* Serialise the printks */
 
-               spin_lock(&lock);
+               raw_spin_lock(&lock);
                printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
                show_regs(regs);
                dump_stack();
-               spin_unlock(&lock);
+               raw_spin_unlock(&lock);
                cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
 
                rc = 1;