Commit | Line | Data |
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39c715b7 IM |
1 | /* |
2 | * lib/smp_processor_id.c | |
3 | * | |
4 | * DEBUG_PREEMPT variant of smp_processor_id(). | |
5 | */ | |
8bc3bcc9 | 6 | #include <linux/export.h> |
39c715b7 | 7 | #include <linux/kallsyms.h> |
4e57b681 | 8 | #include <linux/sched.h> |
39c715b7 | 9 | |
6e766410 | 10 | notrace unsigned int debug_smp_processor_id(void) |
39c715b7 | 11 | { |
39c715b7 | 12 | int this_cpu = raw_smp_processor_id(); |
39c715b7 | 13 | |
4a2b4b22 | 14 | if (likely(preempt_count())) |
39c715b7 IM |
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 | */ | |
fa17b507 | 24 | if (cpumask_equal(tsk_cpus_allowed(current), cpumask_of(this_cpu))) |
39c715b7 IM |
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 | */ | |
5568b139 | 36 | preempt_disable_notrace(); |
39c715b7 IM |
37 | |
38 | if (!printk_ratelimit()) | |
39 | goto out_enable; | |
40 | ||
b41ecbeb AM |
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); | |
39c715b7 IM |
44 | print_symbol("caller is %s\n", (long)__builtin_return_address(0)); |
45 | dump_stack(); | |
46 | ||
47 | out_enable: | |
5568b139 | 48 | preempt_enable_no_resched_notrace(); |
39c715b7 IM |
49 | out: |
50 | return this_cpu; | |
51 | } | |
52 | ||
53 | EXPORT_SYMBOL(debug_smp_processor_id); | |
54 |