1981. [bug] win32: condition.c:wait() could fail to reattain

                        the mutex lock.

diff --git a/CHANGES b/CHANGES
index 58f01a9f3dcedef1fdedee4386e8d80cafbfeaf0..9594f51a8859ed26579e6af1e54b145baec7af3b 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+1981.  [bug]           win32: condition.c:wait() could fail to reattain
+                       the mutex lock.
+
 1980.  [func]          dnssec-signzone: output the SOA record as the
                        first record in the signed zone. [RT #15758]
 

diff --git a/lib/isc/win32/condition.c b/lib/isc/win32/condition.c
index a2a630665120115a386a8772662be07d557d0193..5eb28c11a0ae256f1c01de91be60f76b18d0388d 100644 (file)
--- a/lib/isc/win32/condition.c
+++ b/lib/isc/win32/condition.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: condition.c,v 1.18 2004/03/05 05:11:56 marka Exp $ */
+/* $Id: condition.c,v 1.19 2006/02/13 03:35:47 marka Exp $ */
 
 #include <config.h>
 
@@ -91,6 +91,7 @@ isc_result_t
 isc_condition_destroy(isc_condition_t *cond) {
 
        REQUIRE(cond != NULL);
+       REQUIRE(cond->waiters == 0);
 
        (void)CloseHandle(cond->events[LSIGNAL]);
        (void)CloseHandle(cond->events[LBROADCAST]);
@@ -98,6 +99,15 @@ isc_condition_destroy(isc_condition_t *cond) {
        return (ISC_R_SUCCESS);
 }
 
+/*
+ * This is always called when the mutex (lock) is held, but because
+ * we are waiting we need to release it and reacquire it as soon as the wait
+ * is over. This allows other threads to make use of the object guarded
+ * by the mutex but it should never try to delete it as long as the
+ * number of waiters > 0. Always reacquire the mutex regardless of the
+ * result of the wait. Note that EnterCriticalSection will wait to acquire
+ * the mutex.
+ */
 static isc_result_t
 wait(isc_condition_t *cond, isc_mutex_t *mutex, DWORD milliseconds) {
        DWORD result;
@@ -105,16 +115,15 @@ wait(isc_condition_t *cond, isc_mutex_t *mutex, DWORD milliseconds) {
        cond->waiters++;
        LeaveCriticalSection(mutex);
        result = WaitForMultipleObjects(2, cond->events, FALSE, milliseconds);
+       EnterCriticalSection(mutex);
+       cond->waiters--;
        if (result == WAIT_FAILED) {
                /* XXX */
                return (ISC_R_UNEXPECTED);
        }
-       EnterCriticalSection(mutex);
-       cond->waiters--;
        if (cond->waiters == 0 &&
            !ResetEvent(cond->events[LBROADCAST])) {
                /* XXX */
-               LeaveCriticalSection(mutex);
                return (ISC_R_UNEXPECTED);
        }