From 4d2c1d532bb44320afcf4debfee9ded403647e1e Mon Sep 17 00:00:00 2001
From: Jeffrey Altman <jaltman@secure-endpoints.com>
Date: Fri, 28 Dec 2007 15:46:05 +0000
Subject: [PATCH] windows-syncop-20071228

LICENSE MIT

avoid a race condition between cm_SyncOpCheckContinue and cm_SyncOpDone
that can leave a request on an scp stuck in the waiting state even though
there are no other requests to wake it up.
---
 src/WINNT/afsd/cm_scache.c | 13 +++++--------
 src/WINNT/afsd/cm_scache.h |  8 ++++----
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/src/WINNT/afsd/cm_scache.c b/src/WINNT/afsd/cm_scache.c
index 849bb10..36d41a5 100644
--- a/src/WINNT/afsd/cm_scache.c
+++ b/src/WINNT/afsd/cm_scache.c
@@ -1276,22 +1276,19 @@ long cm_SyncOp(cm_scache_t *scp, cm_buf_t *bufp, cm_user_t *userp, cm_req_t *req
             scp->waitCount = scp->waitRequests = 1;
         }
 
-        if (bufLocked) 
-            lock_ReleaseMutex(&bufp->mx);
-
         cm_SyncOpAddToWaitQueue(scp, flags, bufp);
         wakeupCycle = 0;
         do {
-            if (wakeupCycle++ != 0)
-                lock_ObtainMutex(&scp->mx);
+            if (bufLocked) 
+                lock_ReleaseMutex(&bufp->mx);
             osi_SleepM((LONG_PTR) &scp->flags, &scp->mx);
+            if (bufLocked) 
+                lock_ObtainMutex(&bufp->mx);
+            lock_ObtainMutex(&scp->mx);
         } while (!cm_SyncOpCheckContinue(scp, flags, bufp));
 
 	smb_UpdateServerPriority();
 
-        if (bufLocked) 
-            lock_ObtainMutex(&bufp->mx);
-        lock_ObtainMutex(&scp->mx);
         scp->waitCount--;
         osi_Log3(afsd_logp, "CM SyncOp woke! scp 0x%p; still waiting %d threads of %d requests", 
                  scp, scp->waitCount, scp->waitRequests);
diff --git a/src/WINNT/afsd/cm_scache.h b/src/WINNT/afsd/cm_scache.h
index 1c23479..f353b5d 100644
--- a/src/WINNT/afsd/cm_scache.h
+++ b/src/WINNT/afsd/cm_scache.h
@@ -315,18 +315,18 @@ typedef struct cm_scache {
 				    (fidp)->unique))	\
 					% cm_data.scacheHashTableSize)
 
+#include "cm_conn.h"
+#include "cm_buf.h"
+
 typedef struct cm_scache_waiter {
     osi_queue_t q;
     afs_int32   threadId;
 
     cm_scache_t *scp;
     afs_int32   flags;
-    void        *bufp;
+    cm_buf_t    *bufp;
 } cm_scache_waiter_t;
 
-#include "cm_conn.h"
-#include "cm_buf.h"
-
 extern void cm_InitSCache(int, long);
 
 #ifdef DEBUG_REFCOUNT
-- 
1.9.4