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path: root/lib/dump_stack.c (plain)
blob: c30d07e99dba4cc32be6aeb4d353d79058509b4b
1/*
2 * Provide a default dump_stack() function for architectures
3 * which don't implement their own.
4 */
5
6#include <linux/kernel.h>
7#include <linux/export.h>
8#include <linux/sched.h>
9#include <linux/smp.h>
10#include <linux/atomic.h>
11
12static void __dump_stack(void)
13{
14 dump_stack_print_info(KERN_DEFAULT);
15 show_stack(NULL, NULL);
16}
17
18/**
19 * dump_stack - dump the current task information and its stack trace
20 *
21 * Architectures can override this implementation by implementing its own.
22 */
23#ifdef CONFIG_SMP
24static atomic_t dump_lock = ATOMIC_INIT(-1);
25
26asmlinkage __visible void dump_stack(void)
27{
28 unsigned long flags;
29 int was_locked;
30 int old;
31 int cpu;
32
33 /*
34 * Permit this cpu to perform nested stack dumps while serialising
35 * against other CPUs
36 */
37retry:
38 local_irq_save(flags);
39 cpu = smp_processor_id();
40 old = atomic_cmpxchg(&dump_lock, -1, cpu);
41 if (old == -1) {
42 was_locked = 0;
43 } else if (old == cpu) {
44 was_locked = 1;
45 } else {
46 local_irq_restore(flags);
47 cpu_relax();
48 goto retry;
49 }
50
51 __dump_stack();
52
53 if (!was_locked)
54 atomic_set(&dump_lock, -1);
55
56 local_irq_restore(flags);
57}
58#else
59asmlinkage __visible void dump_stack(void)
60{
61 __dump_stack();
62}
63#endif
64EXPORT_SYMBOL(dump_stack);
65