Windows: add osi_TWaitExt(), fix osi_TWait()

osi_TWait() was adding new locks to the turnstile at the tail
which is the end of the queue locks are removed from.  This
implemented LIFO instead of FIFO when FIFO is the "fair" order
to service lock requests.

osi_TWaitExt() is added to permit the Reader to Writer upgrade
request to use LIFO when more than one reader is present.

Change-Id: Ib6435a3edc2cb8519939cfad93e0db4b0604da2d
Reviewed-on: http://gerrit.openafs.org/6435
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>

diff --git a/src/WINNT/client_osi/osibasel.c b/src/WINNT/client_osi/osibasel.c
index 20444f815c3f6063fce2bbba447e4a597f75f0c2..192a22c4be86dbe0eeee4fcfe3b5e7230e20cf06 100644 (file)
--- a/src/WINNT/client_osi/osibasel.c
+++ b/src/WINNT/client_osi/osibasel.c
@@ -445,7 +445,7 @@ void lock_ConvertRToW(osi_rwlock_t *lockp)
         osi_assertx(lockp->readers > 0, "read lock underflow");
 
         lockp->waiters++;
-        osi_TWait(&lockp->d.turn, OSI_SLEEPINFO_W4WRITE, &lockp->flags, lockp->tid, csp);
+        osi_TWaitExt(&lockp->d.turn, OSI_SLEEPINFO_W4WRITE, &lockp->flags, lockp->tid, csp, FALSE);
         lockp->waiters--;
         osi_assertx(lockp->waiters >= 0, "waiters underflow");
         osi_assert(lockp->readers == 0 && (lockp->flags & OSI_LOCKFLAG_EXCL));

diff --git a/src/WINNT/client_osi/osisleep.c b/src/WINNT/client_osi/osisleep.c
index a8109363b1e32639810b19c815a664f0732a178b..5b2e0d4ffb95c08a88d4ec81ca21963a63e47947 100644 (file)
--- a/src/WINNT/client_osi/osisleep.c
+++ b/src/WINNT/client_osi/osisleep.c
@@ -259,6 +259,11 @@ void osi_Init(void)
 }
 
 void osi_TWait(osi_turnstile_t *turnp, int waitFor, void *patchp, DWORD *tidp, CRITICAL_SECTION *releasep)
+{
+    osi_TWaitExt(turnp, waitFor, patchp, tidp, releasep, TRUE);
+}
+
+void osi_TWaitExt(osi_turnstile_t *turnp, int waitFor, void *patchp, DWORD *tidp, CRITICAL_SECTION *releasep, int prepend)
 {
     osi_sleepInfo_t *sp;
     unsigned int code;
@@ -275,9 +280,10 @@ void osi_TWait(osi_turnstile_t *turnp, int waitFor, void *patchp, DWORD *tidp, C
     sp->waitFor = waitFor;
     sp->value = (LONG_PTR) patchp;
     sp->tidp   = tidp;
-    osi_QAddT((osi_queue_t **) &turnp->firstp, (osi_queue_t **) &turnp->lastp, &sp->q);
-    if (!turnp->lastp)
-       turnp->lastp = sp;
+    if (prepend)
+        osi_QAddH((osi_queue_t **) &turnp->firstp, (osi_queue_t **) &turnp->lastp, &sp->q);
+    else
+        osi_QAddT((osi_queue_t **) &turnp->firstp, (osi_queue_t **) &turnp->lastp, &sp->q);
     LeaveCriticalSection(releasep);
 
     /* now wait for the signal */

diff --git a/src/WINNT/client_osi/osisleep.h b/src/WINNT/client_osi/osisleep.h
index 0c3fe46798f456d623e26f204d4c7b31f10aa843..b833d26dab9b52925c44061f6ffeebffe6b29865 100644 (file)
--- a/src/WINNT/client_osi/osisleep.h
+++ b/src/WINNT/client_osi/osisleep.h
@@ -149,6 +149,10 @@ extern void osi_TWait(osi_turnstile_t *turnp, int waitFor,
                       void *patchp, DWORD *tidp,
                       Crit_Sec *releasep);
 
+extern void osi_TWaitExt(osi_turnstile_t *turnp, int waitFor,
+                         void *patchp, DWORD *tidp,
+                         Crit_Sec *releasep, int prepend);
+
 extern void osi_TSignal(osi_turnstile_t *turnp);
 
 extern void osi_TBroadcast(osi_turnstile_t *turnp);