smp_processor_id.c 1.1 KB

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  1. /*
  2. * lib/smp_processor_id.c
  3. *
  4. * DEBUG_PREEMPT variant of smp_processor_id().
  5. */
  6. #include <linux/module.h>
  7. #include <linux/kallsyms.h>
  8. #include <linux/sched.h>
  9. unsigned int debug_smp_processor_id(void)
  10. {
  11. unsigned long preempt_count = preempt_count();
  12. int this_cpu = raw_smp_processor_id();
  13. cpumask_t this_mask;
  14. if (likely(preempt_count))
  15. goto out;
  16. if (irqs_disabled())
  17. goto out;
  18. /*
  19. * Kernel threads bound to a single CPU can safely use
  20. * smp_processor_id():
  21. */
  22. this_mask = cpumask_of_cpu(this_cpu);
  23. if (cpus_equal(current->cpus_allowed, this_mask))
  24. goto out;
  25. /*
  26. * It is valid to assume CPU-locality during early bootup:
  27. */
  28. if (system_state != SYSTEM_RUNNING)
  29. goto out;
  30. /*
  31. * Avoid recursion:
  32. */
  33. preempt_disable();
  34. if (!printk_ratelimit())
  35. goto out_enable;
  36. printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] code: %s/%d\n", preempt_count(), current->comm, current->pid);
  37. print_symbol("caller is %s\n", (long)__builtin_return_address(0));
  38. dump_stack();
  39. out_enable:
  40. preempt_enable_no_resched();
  41. out:
  42. return this_cpu;
  43. }
  44. EXPORT_SYMBOL(debug_smp_processor_id);