kernel/locking/mutex.h

   1 /*
   2  * Mutexes: blocking mutual exclusion locks
   3  *
   4  * started by Ingo Molnar:
   5  *
   6  *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   7  *
   8  * This file contains mutex debugging related internal prototypes, for the
   9  * !CONFIG_DEBUG_MUTEXES case. Most of them are NOPs:
  10  */
  11
  12 #define spin_lock_mutex(lock, flags) \
  13                 do { spin_lock(lock); (void)(flags); } while (0)
  14 #define spin_unlock_mutex(lock, flags) \
  15                 do { spin_unlock(lock); (void)(flags); } while (0)
  16 #define mutex_remove_waiter(lock, waiter, task) \
  17                 __list_del((waiter)->list.prev, (waiter)->list.next)
  18
  19 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
  20 /*
  21  * The mutex owner can get read and written to locklessly.
  22  * We should use WRITE_ONCE when writing the owner value to
  23  * avoid store tearing, otherwise, a thread could potentially
  24  * read a partially written and incomplete owner value.
  25  */
  26 static inline void mutex_set_owner(struct mutex *lock)
  27 {
  28         WRITE_ONCE(lock->owner, current);
  29 }
  30
  31 static inline void mutex_clear_owner(struct mutex *lock)
  32 {
  33         WRITE_ONCE(lock->owner, NULL);
  34 }
  35 #else
  36 static inline void mutex_set_owner(struct mutex *lock)
  37 {
  38 }
  39
  40 static inline void mutex_clear_owner(struct mutex *lock)
  41 {
  42 }
  43 #endif
  44
  45 #define debug_mutex_wake_waiter(lock, waiter)           do { } while (0)
  46 #define debug_mutex_free_waiter(waiter)                 do { } while (0)
  47 #define debug_mutex_add_waiter(lock, waiter, ti)        do { } while (0)
  48 #define debug_mutex_unlock(lock)                        do { } while (0)
  49 #define debug_mutex_init(lock, name, key)               do { } while (0)
  50
  51 static inline void
  52 debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
  53 {
  54 }