git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/two_state_shared_lock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "two_state_shared_lock.h"
   4
   5 void bch2_two_state_unlock(two_state_lock_t *lock, int s)
   6 {
   7         long i = s ? 1 : -1;
   8
   9         BUG_ON(atomic_long_read(&lock->v) == 0);
  10
  11         if (atomic_long_sub_return_release(i, &lock->v) == 0)
  12                 wake_up_all(&lock->wait);
  13 }
  14
  15 bool bch2_two_state_trylock(two_state_lock_t *lock, int s)
  16 {
  17         long i = s ? 1 : -1;
  18         long v = atomic_long_read(&lock->v), old;
  19
  20         do {
  21                 old = v;
  22
  23                 if (i > 0 ? v < 0 : v > 0)
  24                         return false;
  25         } while ((v = atomic_long_cmpxchg_acquire(&lock->v,
  26                                         old, old + i)) != old);
  27         return true;
  28 }
  29
  30 void bch2_two_state_lock(two_state_lock_t *lock, int s)
  31 {
  32         wait_event(lock->wait, bch2_two_state_trylock(lock, s));
  33 }