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 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
  38 retry:
  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
  58 asmlinkage void dump_stack(void)
  59 {
  60         __dump_stack();
  61 }
  62 #endif
  63 EXPORT_SYMBOL(dump_stack);