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);