[zion] Move synchronization to the message queue

zion/object/ipc_object.cpp

@@ -5,31 +5,11 @@
 glcr::ErrorCode IpcObject::Send(uint64_t num_bytes, const void* bytes,
                                 uint64_t num_caps, const z_cap_t* caps) {
   auto& message_queue = GetSendMessageQueue();
-  MutexHolder lock(mutex_);
-  RET_ERR(message_queue.PushBack(num_bytes, bytes, num_caps, caps));
-
-  if (blocked_threads_.size() > 0) {
-    auto thread = blocked_threads_.PopFront();
-    thread->SetState(Thread::RUNNABLE);
-    gScheduler->Enqueue(thread);
-  }
-  return glcr::OK;
+  return message_queue.PushBack(num_bytes, bytes, num_caps, caps);
 }
 
 glcr::ErrorCode IpcObject::Recv(uint64_t* num_bytes, void* bytes,
                                 uint64_t* num_caps, z_cap_t* caps) {
   auto& message_queue = GetRecvMessageQueue();
-  mutex_.Lock();
-  while (message_queue.empty()) {
-    auto thread = gScheduler->CurrentThread();
-    thread->SetState(Thread::BLOCKED);
-    blocked_threads_.PushBack(thread);
-    mutex_.Unlock();
-    gScheduler->Yield();
-    mutex_.Lock();
-  }
-  mutex_.Unlock();
-
-  MutexHolder lock(mutex_);
   return message_queue.PopFront(num_bytes, bytes, num_caps, caps);
 }

zion/object/ipc_object.h

@@ -1,11 +1,9 @@
 #pragma once
 
-#include <glacier/container/intrusive_list.h>
 #include <glacier/status/error.h>
 
 #include "include/ztypes.h"
 #include "lib/message_queue.h"
-#include "lib/mutex.h"
 #include "object/kernel_object.h"
 
 class IpcObject : public KernelObject {
@@ -18,16 +16,8 @@ class IpcObject : public KernelObject {
   virtual glcr::ErrorCode Recv(uint64_t* num_bytes, void* bytes,
                                uint64_t* num_caps, z_cap_t* caps) final;
 
-  bool HasMessages() {
-    MutexHolder h(mutex_);
-    return !GetRecvMessageQueue().empty();
-  }
+  bool HasMessages() { return !GetRecvMessageQueue().empty(); }
 
   virtual MessageQueue& GetSendMessageQueue() = 0;
   virtual MessageQueue& GetRecvMessageQueue() = 0;
-
- protected:
-  // FIXME: move locking and blocked threads to the message queue itself.
-  Mutex mutex_{"ipc"};
-  glcr::IntrusiveList<Thread> blocked_threads_;
 };

zion/object/port.cpp

@@ -3,6 +3,5 @@
 #include "scheduler/scheduler.h"
 
 void Port::WriteKernel(uint64_t init, glcr::RefPtr<Capability> cap) {
-  MutexHolder h(mutex_);
   message_queue_.WriteKernel(init, cap);
 }