Windows: correct cm_buf use of Head/Tail queues

The buffer free list least recently used queue has both
head and tail points.  Use the proper versions of the queue
mgmt functions and do not handle edge cases as special cases.

Reviewed-on: http://gerrit.openafs.org/5354
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
(cherry picked from commit 537592f6bbda0c659c25ae7068f50504e2a5e116)

Change-Id: I0d5afaf59895f34ced739f4626a351fe41186008
Reviewed-on: http://gerrit.openafs.org/6030
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>

diff --git a/src/WINNT/afsd/cm_buf.c b/src/WINNT/afsd/cm_buf.c
index 0dc0f4b3bdc29b623e0394c94f2e7c815970d166..42f24722e8587cac52e38969135a269565c2e1a1 100644 (file)
--- a/src/WINNT/afsd/cm_buf.c
+++ b/src/WINNT/afsd/cm_buf.c
@@ -161,11 +161,9 @@ void buf_ReleaseLocked(cm_buf_t *bp, afs_uint32 writeLocked)
 
         if (bp->refCount == 0 &&
             !(bp->qFlags & CM_BUF_QINLRU)) {
-            osi_QAdd((osi_queue_t **) &cm_data.buf_freeListp, &bp->q);
-
-            /* watch for transition from empty to one element */
-            if (!cm_data.buf_freeListEndp)
-                cm_data.buf_freeListEndp = cm_data.buf_freeListp;
+            osi_QAddH( (osi_queue_t **) &cm_data.buf_freeListp,
+                       (osi_queue_t **) &cm_data.buf_freeListEndp,
+                       &bp->q);
             _InterlockedOr(&bp->qFlags, CM_BUF_QINLRU);
         }
 
@@ -201,11 +199,9 @@ void buf_Release(cm_buf_t *bp)
         lock_ObtainWrite(&buf_globalLock);
         if (bp->refCount == 0 &&
             !(bp->qFlags & CM_BUF_QINLRU)) {
-            osi_QAdd((osi_queue_t **) &cm_data.buf_freeListp, &bp->q);
-
-            /* watch for transition from empty to one element */
-            if (!cm_data.buf_freeListEndp)
-                cm_data.buf_freeListEndp = cm_data.buf_freeListp;
+            osi_QAddH( (osi_queue_t **) &cm_data.buf_freeListp,
+                       (osi_queue_t **) &cm_data.buf_freeListEndp,
+                       &bp->q);
             _InterlockedOr(&bp->qFlags, CM_BUF_QINLRU);
         }
         lock_ReleaseWrite(&buf_globalLock);
@@ -480,17 +476,15 @@ long buf_Init(int newFile, cm_buf_ops_t *opsp, afs_uint64 nbuffers)
                 bp->allp = cm_data.buf_allp;
                 cm_data.buf_allp = bp;
 
-                osi_QAdd((osi_queue_t **)&cm_data.buf_freeListp, &bp->q);
+                osi_QAddH( (osi_queue_t **) &cm_data.buf_freeListp,
+                           (osi_queue_t **) &cm_data.buf_freeListEndp,
+                           &bp->q);
                 _InterlockedOr(&bp->qFlags, CM_BUF_QINLRU);
                 lock_InitializeMutex(&bp->mx, "Buffer mutex", LOCK_HIERARCHY_BUFFER);
 
                 /* grab appropriate number of bytes from aligned zone */
                 bp->datap = data;
 
-                /* setup last buffer pointer */
-                if (i == 0)
-                    cm_data.buf_freeListEndp = bp;
-
                 /* next */
                 bp++;
                 data += cm_data.buf_blockSize;
@@ -1086,17 +1080,15 @@ long buf_GetNewLocked(struct cm_scache *scp, osi_hyper_t *offsetp, cm_req_t *req
                 cm_data.buf_fileHashTablepp[i] = bp;
             }
 
-            /* we should move it from the lru queue.  It better still be there,
+            /* we should remove it from the lru queue.  It better still be there,
              * since we've held the global (big) lock since we found it there.
              */
             osi_assertx(bp->qFlags & CM_BUF_QINLRU,
                          "buf_GetNewLocked: LRU screwup");
 
-            if (cm_data.buf_freeListEndp == bp) {
-                /* we're the last guy in this queue, so maintain it */
-                cm_data.buf_freeListEndp = (cm_buf_t *) osi_QPrev(&bp->q);
-            }
-            osi_QRemove((osi_queue_t **) &cm_data.buf_freeListp, &bp->q);
+            osi_QRemoveHT( (osi_queue_t **) &cm_data.buf_freeListp,
+                           (osi_queue_t **) &cm_data.buf_freeListEndp,
+                           &bp->q);
             _InterlockedAnd(&bp->qFlags, ~CM_BUF_QINLRU);
 
             /* prepare to return it.  Give it a refcount */
@@ -1270,9 +1262,9 @@ long buf_Get(struct cm_scache *scp, osi_hyper_t *offsetp, cm_req_t *reqp, cm_buf
      */
     lock_ObtainWrite(&buf_globalLock);
     if (bp->qFlags & CM_BUF_QINLRU) {
-        if (cm_data.buf_freeListEndp == bp)
-            cm_data.buf_freeListEndp = (cm_buf_t *) osi_QPrev(&bp->q);
-        osi_QRemove((osi_queue_t **) &cm_data.buf_freeListp, &bp->q);
+        osi_QRemoveHT( (osi_queue_t **) &cm_data.buf_freeListp,
+                       (osi_queue_t **) &cm_data.buf_freeListEndp,
+                       &bp->q);
         _InterlockedAnd(&bp->qFlags, ~CM_BUF_QINLRU);
     }
     lock_ReleaseWrite(&buf_globalLock);