Added some locking to ports to prevent the case where two threads simultaneously wake up a task blocked on a certain port.

src/rt/rust_chan.cpp

@@ -31,6 +31,7 @@ rust_chan::~rust_chan() {
 void rust_chan::associate(maybe_proxy<rust_port> *port) {
     this->port = port;
     if (port->is_proxy() == false) {
+        scoped_lock sync(port->referent()->lock);
         LOG(task, task,
             "associating chan: 0x%" PRIxPTR " with port: 0x%" PRIxPTR,
             this, port);
@@ -49,6 +50,7 @@ void rust_chan::disassociate() {
     A(task->dom, is_associated(), "Channel must be associated with a port.");
 
     if (port->is_proxy() == false) {
+        scoped_lock sync(port->referent()->lock);
         LOG(task, task,
             "disassociating chan: 0x%" PRIxPTR " from port: 0x%" PRIxPTR,
             this, port->referent());
@@ -81,6 +83,7 @@ void rust_chan::send(void *sptr) {
         buffer.dequeue(NULL);
     } else {
         rust_port *target_port = port->referent();
+        scoped_lock sync(target_port->lock);
         if (target_port->task->blocked_on(target_port)) {
             DLOG(dom, comm, "dequeued in rendezvous_ptr");
             buffer.dequeue(target_port->task->rendezvous_ptr);

src/rt/rust_port.h

@@ -13,6 +13,8 @@ public:
     // Data sent to this port from remote tasks is buffered in this channel.
     rust_chan *remote_channel;
 
+    lock_and_signal lock;
+
     rust_port(rust_task *task, size_t unit_sz);
     ~rust_port();
     void log_state();

src/rt/rust_task.cpp

@@ -170,10 +170,7 @@ rust_task::start(uintptr_t spawnee_fn,
     ctx.call((void *)task_start_wrapper, a, sp);
 
     yield_timer.reset(0);
-    {
+    transition(&dom->newborn_tasks, &dom->running_tasks);
-        scoped_lock sync(dom->scheduler_lock);
-        transition(&dom->newborn_tasks, &dom->running_tasks);
-    }
 }
 
 void
@@ -408,6 +405,7 @@ rust_task::free(void *p, bool is_gc)
 
 void
 rust_task::transition(rust_task_list *src, rust_task_list *dst) {
+    scoped_lock sync(dom->scheduler_lock);
     DLOG(dom, task,
          "task %s " PTR " state change '%s' -> '%s' while in '%s'",
          name, (uintptr_t)this, src->name, dst->name, state->name);
@@ -424,10 +422,7 @@ rust_task::block(rust_cond *on, const char* name) {
     A(dom, cond == NULL, "Cannot block an already blocked task.");
     A(dom, on != NULL, "Cannot block on a NULL object.");
 
-    {
+    transition(&dom->running_tasks, &dom->blocked_tasks);
-        scoped_lock sync(dom->scheduler_lock);
-        transition(&dom->running_tasks, &dom->blocked_tasks);
-    }
     cond = on;
     cond_name = name;
 }
@@ -439,10 +434,7 @@ rust_task::wakeup(rust_cond *from) {
                         (uintptr_t) cond, (uintptr_t) from);
     A(dom, cond == from, "Cannot wake up blocked task on wrong condition.");
 
-    {
+    transition(&dom->blocked_tasks, &dom->running_tasks);
-        scoped_lock sync(dom->scheduler_lock);
-        transition(&dom->blocked_tasks, &dom->running_tasks);
-    }
     I(dom, cond == from);
     cond = NULL;
     cond_name = "none";
@@ -450,7 +442,6 @@ rust_task::wakeup(rust_cond *from) {
 
 void
 rust_task::die() {
-    scoped_lock sync(dom->scheduler_lock);
     transition(&dom->running_tasks, &dom->dead_tasks);
 }