Adding packet forward test cases involving multiple VMs
[kvmfornfv.git] / kernel / 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
12 static 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
24 static atomic_t dump_lock = ATOMIC_INIT(-1);
25
26 asmlinkage __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          */
37 retry:
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
59 asmlinkage __visible void dump_stack(void)
60 {
61         __dump_stack();
62 }
63 #endif
64 EXPORT_SYMBOL(dump_stack);