| 1 | /* |
| 2 | * lib/smp_processor_id.c |
| 3 | * |
| 4 | * DEBUG_PREEMPT variant of smp_processor_id(). |
| 5 | */ |
| 6 | #include <linux/export.h> |
| 7 | #include <linux/kallsyms.h> |
| 8 | #include <linux/sched.h> |
| 9 | |
| 10 | notrace unsigned int debug_smp_processor_id(void) |
| 11 | { |
| 12 | int this_cpu = raw_smp_processor_id(); |
| 13 | |
| 14 | if (likely(preempt_count())) |
| 15 | goto out; |
| 16 | |
| 17 | if (irqs_disabled()) |
| 18 | goto out; |
| 19 | |
| 20 | /* |
| 21 | * Kernel threads bound to a single CPU can safely use |
| 22 | * smp_processor_id(): |
| 23 | */ |
| 24 | if (cpumask_equal(tsk_cpus_allowed(current), cpumask_of(this_cpu))) |
| 25 | goto out; |
| 26 | |
| 27 | /* |
| 28 | * It is valid to assume CPU-locality during early bootup: |
| 29 | */ |
| 30 | if (system_state != SYSTEM_RUNNING) |
| 31 | goto out; |
| 32 | |
| 33 | /* |
| 34 | * Avoid recursion: |
| 35 | */ |
| 36 | preempt_disable_notrace(); |
| 37 | |
| 38 | if (!printk_ratelimit()) |
| 39 | goto out_enable; |
| 40 | |
| 41 | printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] " |
| 42 | "code: %s/%d\n", |
| 43 | preempt_count() - 1, current->comm, current->pid); |
| 44 | print_symbol("caller is %s\n", (long)__builtin_return_address(0)); |
| 45 | dump_stack(); |
| 46 | |
| 47 | out_enable: |
| 48 | preempt_enable_no_resched_notrace(); |
| 49 | out: |
| 50 | return this_cpu; |
| 51 | } |
| 52 | |
| 53 | EXPORT_SYMBOL(debug_smp_processor_id); |
| 54 | |