X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FSchedule.c;h=375520d011327b8d7cb885b353394db5273d06be;hb=8cc74db64356bd332a11c73788c4108e2e3c5acd;hp=5ebb685a027d750690dacbabb435efb0cc3c5411;hpb=45202530612593a0ba7a6c559a38dc1ff26670a4;p=ghc-hetmet.git

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 5ebb685..375520d 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -2137,16 +2137,34 @@ forkProcess(HsStablePtr *entry
     // ToDo: for SMP, we should probably acquire *all* the capabilities
     cap = rts_lock();
     
+    // no funny business: hold locks while we fork, otherwise if some
+    // other thread is holding a lock when the fork happens, the data
+    // structure protected by the lock will forever be in an
+    // inconsistent state in the child.  See also #1391.
+    ACQUIRE_LOCK(&sched_mutex);
+    ACQUIRE_LOCK(&cap->lock);
+    ACQUIRE_LOCK(&cap->running_task->lock);
+
     pid = fork();
     
     if (pid) { // parent
 	
+        RELEASE_LOCK(&sched_mutex);
+        RELEASE_LOCK(&cap->lock);
+        RELEASE_LOCK(&cap->running_task->lock);
+
 	// just return the pid
 	rts_unlock(cap);
 	return pid;
 	
     } else { // child
 	
+#if defined(THREADED_RTS)
+        initMutex(&sched_mutex);
+        initMutex(&cap->lock);
+        initMutex(&cap->running_task->lock);
+#endif
+
 	// Now, all OS threads except the thread that forked are
 	// stopped.  We need to stop all Haskell threads, including
 	// those involved in foreign calls.  Also we need to delete
@@ -2184,6 +2202,9 @@ forkProcess(HsStablePtr *entry
 	ACQUIRE_LOCK(&sched_mutex);
 	for (task = all_tasks; task != NULL; task=task->all_link) {
 	    if (task != cap->running_task) {
+#if defined(THREADED_RTS)
+                initMutex(&task->lock); // see #1391
+#endif
 		discardTask(task);
 	    }
 	}