blob: 6c90fb90e19c2ec25571947b7b98f88262e23ba4 [file] [log] [blame]
Ingo Molnar39c715b2005-06-21 17:14:34 -07001/*
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>
Tim Schmielau4e57b682005-10-30 15:03:48 -08008#include <linux/sched.h>
Ingo Molnar39c715b2005-06-21 17:14:34 -07009
10unsigned int debug_smp_processor_id(void)
11{
12 unsigned long preempt_count = preempt_count();
13 int this_cpu = raw_smp_processor_id();
14 cpumask_t this_mask;
15
16 if (likely(preempt_count))
17 goto out;
18
19 if (irqs_disabled())
20 goto out;
21
22 /*
23 * Kernel threads bound to a single CPU can safely use
24 * smp_processor_id():
25 */
26 this_mask = cpumask_of_cpu(this_cpu);
27
28 if (cpus_equal(current->cpus_allowed, this_mask))
29 goto out;
30
31 /*
32 * It is valid to assume CPU-locality during early bootup:
33 */
34 if (system_state != SYSTEM_RUNNING)
35 goto out;
36
37 /*
38 * Avoid recursion:
39 */
40 preempt_disable();
41
42 if (!printk_ratelimit())
43 goto out_enable;
44
Andrew Mortonb41ecbe2008-02-06 01:37:57 -080045 printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] "
46 "code: %s/%d\n",
47 preempt_count() - 1, current->comm, current->pid);
Ingo Molnar39c715b2005-06-21 17:14:34 -070048 print_symbol("caller is %s\n", (long)__builtin_return_address(0));
49 dump_stack();
50
51out_enable:
52 preempt_enable_no_resched();
53out:
54 return this_cpu;
55}
56
57EXPORT_SYMBOL(debug_smp_processor_id);
58