arch/alpha/lib/dec_and_lock.c

   1 /*
   2  * arch/alpha/lib/dec_and_lock.c
   3  *
   4  * ll/sc version of atomic_dec_and_lock()
   5  *
   6  */
   7
   8 #include <linux/spinlock.h>
   9 #include <linux/atomic.h>
  10 #include <linux/export.h>
  11
  12   asm (".text                                   \n\
  13         .global _atomic_dec_and_lock            \n\
  14         .ent _atomic_dec_and_lock               \n\
  15         .align  4                               \n\
  16 _atomic_dec_and_lock:                           \n\
  17         .prologue 0                             \n\
  18 1:      ldl_l   $1, 0($16)                      \n\
  19         subl    $1, 1, $1                       \n\
  20         beq     $1, 2f                          \n\
  21         stl_c   $1, 0($16)                      \n\
  22         beq     $1, 4f                          \n\
  23         mb                                      \n\
  24         clr     $0                              \n\
  25         ret                                     \n\
  26 2:      br      $29, 3f                         \n\
  27 3:      ldgp    $29, 0($29)                     \n\
  28         br      $atomic_dec_and_lock_1..ng      \n\
  29         .subsection 2                           \n\
  30 4:      br      1b                              \n\
  31         .previous                               \n\
  32         .end _atomic_dec_and_lock");
  33
  34 static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
  35 {
  36         /* Slow path */
  37         spin_lock(lock);
  38         if (atomic_dec_and_test(atomic))
  39                 return 1;
  40         spin_unlock(lock);
  41         return 0;
  42 }
  43 EXPORT_SYMBOL(_atomic_dec_and_lock);