root/lib/smp_processor_id.c

DEFINITIONS

1. debug_smp_processor_id

/*
 * lib/smp_processor_id.c
 *
 * DEBUG_PREEMPT variant of smp_processor_id().
 */
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/sched.h>

notrace unsigned int debug_smp_processor_id(void)
{
        unsigned long preempt_count = preempt_count();
        int this_cpu = raw_smp_processor_id();

        if (likely(preempt_count))
                goto out;

        if (irqs_disabled())
                goto out;

        /*
         * Kernel threads bound to a single CPU can safely use
         * smp_processor_id():
         */
        if (cpus_equal(current->cpus_allowed, cpumask_of_cpu(this_cpu)))
                goto out;

        /*
         * It is valid to assume CPU-locality during early bootup:
         */
        if (system_state != SYSTEM_RUNNING)
                goto out;

        /*
         * Avoid recursion:
         */
        preempt_disable_notrace();

        if (!printk_ratelimit())
                goto out_enable;

        printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] "
                        "code: %s/%d\n",
                        preempt_count() - 1, current->comm, current->pid);
        print_symbol("caller is %s\n", (long)__builtin_return_address(0));
        dump_stack();

out_enable:
        preempt_enable_no_resched_notrace();
out:
        return this_cpu;
}

EXPORT_SYMBOL(debug_smp_processor_id);