GNU Linux-libre 4.4.284-gnu1
[releases.git] / lib / smp_processor_id.c
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 static unsigned int check_preemption_disabled(const char *what1,
11                                                         const char *what2)
12 {
13         int this_cpu = raw_smp_processor_id();
14
15         if (likely(preempt_count()))
16                 goto out;
17
18         if (irqs_disabled())
19                 goto out;
20
21         /*
22          * Kernel threads bound to a single CPU can safely use
23          * smp_processor_id():
24          */
25         if (cpumask_equal(tsk_cpus_allowed(current), cpumask_of(this_cpu)))
26                 goto out;
27
28         /*
29          * It is valid to assume CPU-locality during early bootup:
30          */
31         if (system_state != SYSTEM_RUNNING)
32                 goto out;
33
34         /*
35          * Avoid recursion:
36          */
37         preempt_disable_notrace();
38
39         if (!printk_ratelimit())
40                 goto out_enable;
41
42         printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
43                 what1, what2, preempt_count() - 1, current->comm, current->pid);
44
45         print_symbol("caller is %s\n", (long)__builtin_return_address(0));
46         dump_stack();
47
48 out_enable:
49         preempt_enable_no_resched_notrace();
50 out:
51         return this_cpu;
52 }
53
54 notrace unsigned int debug_smp_processor_id(void)
55 {
56         return check_preemption_disabled("smp_processor_id", "");
57 }
58 EXPORT_SYMBOL(debug_smp_processor_id);
59
60 notrace void __this_cpu_preempt_check(const char *op)
61 {
62         check_preemption_disabled("__this_cpu_", op);
63 }
64 EXPORT_SYMBOL(__this_cpu_preempt_check);