blob: 0f8fc22ed1030a200f1fd3c203ca6789c5646ac8 [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
Arnaldo Carvalho de Melo6e766412008-05-12 21:20:41 +020010notrace unsigned int debug_smp_processor_id(void)
Ingo Molnar39c715b2005-06-21 17:14:34 -070011{
12 unsigned long preempt_count = preempt_count();
13 int this_cpu = raw_smp_processor_id();
Ingo Molnar39c715b2005-06-21 17:14:34 -070014
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 */
Mike Travis0bc3cc02008-07-24 18:21:31 -070025 if (cpus_equal(current->cpus_allowed, cpumask_of_cpu(this_cpu)))
Ingo Molnar39c715b2005-06-21 17:14:34 -070026 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 */
Steven Rostedt5568b132008-05-12 21:20:44 +020037 preempt_disable_notrace();
Ingo Molnar39c715b2005-06-21 17:14:34 -070038
39 if (!printk_ratelimit())
40 goto out_enable;
41
Andrew Mortonb41ecbe2008-02-06 01:37:57 -080042 printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] "
43 "code: %s/%d\n",
44 preempt_count() - 1, current->comm, current->pid);
Ingo Molnar39c715b2005-06-21 17:14:34 -070045 print_symbol("caller is %s\n", (long)__builtin_return_address(0));
46 dump_stack();
47
48out_enable:
Steven Rostedt5568b132008-05-12 21:20:44 +020049 preempt_enable_no_resched_notrace();
Ingo Molnar39c715b2005-06-21 17:14:34 -070050out:
51 return this_cpu;
52}
53
54EXPORT_SYMBOL(debug_smp_processor_id);
55