Root/lib/dump_stack.c

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 void dump_stack(void)
27{
28    int was_locked;
29    int old;
30    int cpu;
31
32    /*
33     * Permit this cpu to perform nested stack dumps while serialising
34     * against other CPUs
35     */
36    preempt_disable();
37
38retry:
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        cpu_relax();
47        goto retry;
48    }
49
50    __dump_stack();
51
52    if (!was_locked)
53        atomic_set(&dump_lock, -1);
54
55    preempt_enable();
56}
57#else
58asmlinkage void dump_stack(void)
59{
60    __dump_stack();
61}
62#endif
63EXPORT_SYMBOL(dump_stack);
64

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