Remove more obsolete comments about semaphores.
Commit stopped using semaphores as the sleep/wake mechanism for
heavyweight locks, but some obsolete references to that scheme remained
in comments.  As with similar commit back-patch all the way.
Discussion:
@@ -1222,14 +1222,10 @@ LWLockAcquire(LWLock *lock, LWLockMode mode)
/*
* Wait until awakened.
*
- * Since we share the process wait semaphore with the regular lock
- * manager and ProcWaitForSignal, and we may need to acquire an LWLock
- * while one of those is pending, it is possible that we get awakened
- * for a reason other than being signaled by LWLockRelease. If so,
- * loop back and wait again. Once we've gotten the LWLock,
- * re-increment the sema by the number of additional signals received,
- * so that the lock manager or signal manager will see the received
- * signal when it next waits.
+ * It is possible that we get awakened for a reason other than being
+ * signaled by LWLockRelease. If so, loop back and wait again. Once
+ * we've gotten the LWLock, re-increment the sema by the number of
+ * additional signals received.
*/
LOG_LWDEBUG("LWLockAcquire", lock, "waiting");
@@ -1389,8 +1385,7 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode)
{
/*
* Wait until awakened. Like in LWLockAcquire, be prepared for
- * bogus wakeups, because we share the semaphore with
- * ProcWaitForSignal.
+ * bogus wakeups.
*/
LOG_LWDEBUG("LWLockAcquireOrWait", lock, "waiting");
@@ -1599,14 +1594,10 @@ LWLockWaitForVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
/*
* Wait until awakened.
*
- * Since we share the process wait semaphore with the regular lock
- * manager and ProcWaitForSignal, and we may need to acquire an LWLock
- * while one of those is pending, it is possible that we get awakened
- * for a reason other than being signaled by LWLockRelease. If so,
- * loop back and wait again. Once we've gotten the LWLock,
- * re-increment the sema by the number of additional signals received,
- * so that the lock manager or signal manager will see the received
- * signal when it next waits.
+ * It is possible that we get awakened for a reason other than being
+ * signaled by LWLockRelease. If so, loop back and wait again. Once
+ * we've gotten the LWLock, re-increment the sema by the number of
+ * additional signals received.
*/
LOG_LWDEBUG("LWLockWaitForVar", lock, "waiting");
