Remove more obsolete comments about semaphores.

Commit 6753333f 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 25b93a29, back-patch all the way.

Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CA%2BhUKGLafjB1uzXcy%3D%3D2L3cy7rjHkqOVn7qRYGBjk%3D%3DtMJE7Yg%40mail.gmail.com

diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 6b5960dd20e5c928f5aa2a2093809d4efbe04fad..112f4131b7d6e722294cae688fb4ab9b03020009 100644 (file)
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -1264,14 +1264,10 @@ 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");
 
@@ -1431,8 +1427,7 @@ 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");
 
@@ -1642,14 +1637,10 @@ 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");