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/*

 * lib/smp_processor_id.c

 *

 * DEBUG_PREEMPT variant of smp_processor_id().

 */

#include <linux/module.h>

#include <linux/kallsyms.h>

#include <linux/sched.h>

unsigned int debug_smp_processor_id(void)

{

        unsigned long preempt_count = preempt_count();

        int this_cpu = raw_smp_processor_id();

        cpumask_t this_mask;

        if (likely(preempt_count))

                goto out;

        if (irqs_disabled())

                goto out;

        /*

         * Kernel threads bound to a single CPU can safely use

         * smp_processor_id():

         */

        this_mask = cpumask_of_cpu(this_cpu);

        if (cpus_equal(current->cpus_allowed, this_mask))

                goto out;

        /*

         * It is valid to assume CPU-locality during early bootup:

         */

        if (system_state != SYSTEM_RUNNING)

                goto out;

        /*

         * Avoid recursion:

         */

        preempt_disable();

        if (!printk_ratelimit())

                goto out_enable;

        printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] code: %s/%d\n", preempt_count(), current->comm, current->pid);

        print_symbol("caller is %s\n", (long)__builtin_return_address(0));

        dump_stack();

out_enable:

        preempt_enable_no_resched();

out:

        return this_cpu;

}

EXPORT_SYMBOL(debug_smp_processor_id);