arch/alpha/lib/dec_and_lock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * arch/alpha/lib/dec_and_lock.c
   4  *
   5  * ll/sc version of atomic_dec_and_lock()
   6  *
   7  */
   8
   9 #include <linux/spinlock.h>
  10 #include <linux/atomic.h>
  11 #include <linux/export.h>
  12
  13   asm (".text                                   \n\
  14         .global _atomic_dec_and_lock            \n\
  15         .ent _atomic_dec_and_lock               \n\
  16         .align  4                               \n\
  17 _atomic_dec_and_lock:                           \n\
  18         .prologue 0                             \n\
  19 1:      ldl_l   $1, 0($16)                      \n\
  20         subl    $1, 1, $1                       \n\
  21         beq     $1, 2f                          \n\
  22         stl_c   $1, 0($16)                      \n\
  23         beq     $1, 4f                          \n\
  24         mb                                      \n\
  25         clr     $0                              \n\
  26         ret                                     \n\
  27 2:      br      $29, 3f                         \n\
  28 3:      ldgp    $29, 0($29)                     \n\
  29         br      $atomic_dec_and_lock_1..ng      \n\
  30         .subsection 2                           \n\
  31 4:      br      1b                              \n\
  32         .previous                               \n\
  33         .end _atomic_dec_and_lock");
  34
  35 static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
  36 {
  37         /* Slow path */
  38         spin_lock(lock);
  39         if (atomic_dec_and_test(atomic))
  40                 return 1;
  41         spin_unlock(lock);
  42         return 0;
  43 }
  44 EXPORT_SYMBOL(_atomic_dec_and_lock);