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/sched/debug.h>
  10 #include <linux/smp.h>
  11 #include <linux/atomic.h>
  12
  13 static void __dump_stack(void)
  14 {
  15         dump_stack_print_info(KERN_DEFAULT);
  16         show_stack(NULL, NULL);
  17 }
  18
  19 /**
  20  * dump_stack - dump the current task information and its stack trace
  21  *
  22  * Architectures can override this implementation by implementing its own.
  23  */
  24 #ifdef CONFIG_SMP
  25 static atomic_t dump_lock = ATOMIC_INIT(-1);
  26
  27 asmlinkage __visible void dump_stack(void)
  28 {
  29         unsigned long flags;
  30         int was_locked;
  31         int old;
  32         int cpu;
  33
  34         /*
  35          * Permit this cpu to perform nested stack dumps while serialising
  36          * against other CPUs
  37          */
  38 retry:
  39         local_irq_save(flags);
  40         cpu = smp_processor_id();
  41         old = atomic_cmpxchg(&dump_lock, -1, cpu);
  42         if (old == -1) {
  43                 was_locked = 0;
  44         } else if (old == cpu) {
  45                 was_locked = 1;
  46         } else {
  47                 local_irq_restore(flags);
  48                 cpu_relax();
  49                 goto retry;
  50         }
  51
  52         __dump_stack();
  53
  54         if (!was_locked)
  55                 atomic_set(&dump_lock, -1);
  56
  57         local_irq_restore(flags);
  58 }
  59 #else
  60 asmlinkage __visible void dump_stack(void)
  61 {
  62         __dump_stack();
  63 }
  64 #endif
  65 EXPORT_SYMBOL(dump_stack);