Added two experimental release_sem_etc() flags (both should stay, but they

may be renamed):
- B_RELEASE_ALL: the semaphore count is set to 0, all waiting threads are released
  (the "count" argument of release_etc_sem() is ignored then)
- B_RELEASE_IF_WAITING_ONLY: the semaphore count is only decreased if there
  are any waiting threads; ie. the semaphore is signaled
Together, they will make the pthread_cond_*() functions easy to implement, and
they come in handy at other places, too.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@9329 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/kernel/OS.h

@@ -145,8 +145,12 @@ typedef struct sem_info {
 /* semaphore flags */
 enum {
 	B_CAN_INTERRUPT		= 1,	/* acquisition of the semaphore can be interrupted (system use only) */
-	B_DO_NOT_RESCHEDULE	= 2,	/* thread is not rescheduled after release_sem_etc() */
 	B_CHECK_PERMISSION	= 4,	/* ownership will be checked (system use only) */
+
+	/* release_sem_etc() only flags */
+	B_DO_NOT_RESCHEDULE	= 2,	/* thread is not rescheduled */
+	B_RELEASE_ALL		= 8,	/* all waiting threads will be woken up, count will be zeroed */
+	B_RELEASE_IF_WAITING_ONLY = 16,	/* release count only if there are any threads waiting */
 };
 
 extern sem_id	create_sem(int32 count, const char *name);