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-rw-r--r--lib/smp_processor_id.c55
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
new file mode 100644
index 000000000000..42c08ef828c5
--- /dev/null
+++ b/lib/smp_processor_id.c
@@ -0,0 +1,55 @@
1/*
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>
8
9unsigned int debug_smp_processor_id(void)
10{
11 unsigned long preempt_count = preempt_count();
12 int this_cpu = raw_smp_processor_id();
13 cpumask_t this_mask;
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 this_mask = cpumask_of_cpu(this_cpu);
26
27 if (cpus_equal(current->cpus_allowed, this_mask))
28 goto out;
29
30 /*
31 * It is valid to assume CPU-locality during early bootup:
32 */
33 if (system_state != SYSTEM_RUNNING)
34 goto out;
35
36 /*
37 * Avoid recursion:
38 */
39 preempt_disable();
40
41 if (!printk_ratelimit())
42 goto out_enable;
43
44 printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] code: %s/%d\n", preempt_count(), current->comm, current->pid);
45 print_symbol("caller is %s\n", (long)__builtin_return_address(0));
46 dump_stack();
47
48out_enable:
49 preempt_enable_no_resched();
50out:
51 return this_cpu;
52}
53
54EXPORT_SYMBOL(debug_smp_processor_id);
55