Disallow UI/IO thread blocking on any other thread.

net/base/network_change_notifier_linux.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This implementation of NetworkChangeNotifier's offline state detection
 // depends on D-Bus and NetworkManager, and is known to work on at least
 // GNOME version 2.30.  If D-Bus or NetworkManager are unavailable, this
 // implementation will always behave as if it is online.
 
 #include "net/base/network_change_notifier_linux.h"
 
 #include <errno.h>
 #include <sys/socket.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/eintr_wrapper.h"
 #include "base/file_util.h"
 #include "base/files/file_path_watcher.h"
 #include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread.h"
+#include "base/threading/thread_restrictions.h"
 #include "dbus/bus.h"
 #include "dbus/message.h"
 #include "dbus/object_proxy.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_change_notifier_netlink_linux.h"
 
 using ::base::files::FilePathWatcher;
 
 namespace net {
 
@@ skipping 19 matching lines @@
   NM_STATE_UNKNOWN = 0,
   NM_STATE_ASLEEP = 10,
   NM_STATE_DISCONNECTED = 20,
   NM_STATE_DISCONNECTING = 30,
   NM_STATE_CONNECTING = 40,
   NM_STATE_CONNECTED_LOCAL = 50,
   NM_STATE_CONNECTED_SITE = 60,
   NM_STATE_CONNECTED_GLOBAL = 70
 };
 
+class DNSWatchDelegate : public FilePathWatcher::Delegate {
+ public:
+  explicit DNSWatchDelegate(const base::Closure& callback)
+      : callback_(callback) {}
+  virtual ~DNSWatchDelegate() {}
+  // FilePathWatcher::Delegate interface
+  virtual void OnFilePathChanged(const FilePath& path) OVERRIDE;
+  virtual void OnFilePathError(const FilePath& path) OVERRIDE;
+ private:
+  base::Closure callback_;
+  DISALLOW_COPY_AND_ASSIGN(DNSWatchDelegate);
+};
+
+void DNSWatchDelegate::OnFilePathChanged(const FilePath& path) {
+  // Calls NetworkChangeNotifier::NotifyObserversOfDNSChange().
+  callback_.Run();
+}
+
+void DNSWatchDelegate::OnFilePathError(const FilePath& path) {
+  LOG(ERROR) << "DNSWatchDelegate::OnFilePathError for " << path.value();
+}
+
+}  // namespace
+
 // A wrapper around NetworkManager's D-Bus API.
 class NetworkManagerApi {
  public:
   NetworkManagerApi(const base::Closure& notification_callback, dbus::Bus* bus)
       : is_offline_(false),
         offline_state_initialized_(true /*manual_reset*/, false),
         notification_callback_(notification_callback),
         helper_thread_id_(base::kInvalidThreadId),
         ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)),
         system_bus_(bus) { }
@@ skipping 149 matching lines @@
     case NM_STATE_ASLEEP:
       // Networking disabled or no devices on system
       return true;
     default:
       // Unknown status
       return false;
   }
 }
 
 bool NetworkManagerApi::IsCurrentlyOffline() {
+  // http://crbug.com/125097
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
   offline_state_initialized_.Wait();
   base::AutoLock lock(is_offline_lock_);
   return is_offline_;
 }
 
-class DNSWatchDelegate : public FilePathWatcher::Delegate {
- public:
-  explicit DNSWatchDelegate(const base::Closure& callback)
-      : callback_(callback) {}
-  virtual ~DNSWatchDelegate() {}
-  // FilePathWatcher::Delegate interface
-  virtual void OnFilePathChanged(const FilePath& path) OVERRIDE;
-  virtual void OnFilePathError(const FilePath& path) OVERRIDE;
- private:
-  base::Closure callback_;
-  DISALLOW_COPY_AND_ASSIGN(DNSWatchDelegate);
-};
-
-void DNSWatchDelegate::OnFilePathChanged(const FilePath& path) {
-  // Calls NetworkChangeNotifier::NotifyObserversOfDNSChange().
-  callback_.Run();
-}
-
-void DNSWatchDelegate::OnFilePathError(const FilePath& path) {
-  LOG(ERROR) << "DNSWatchDelegate::OnFilePathError for " << path.value();
-}
-
-}  // namespace
-
 class NetworkChangeNotifierLinux::Thread
     : public base::Thread, public MessageLoopForIO::Watcher {
  public:
   explicit Thread(dbus::Bus* bus);
   virtual ~Thread();
 
   // MessageLoopForIO::Watcher:
   virtual void OnFileCanReadWithoutBlocking(int fd);
   virtual void OnFileCanWriteWithoutBlocking(int /* fd */);
 
@@ skipping 163 matching lines @@
   // Stopping from here allows us to sanity- check that the notifier
   // thread shut down properly.
   notifier_thread_->Stop();
 }
 
 bool NetworkChangeNotifierLinux::IsCurrentlyOffline() const {
   return notifier_thread_->IsCurrentlyOffline();
 }
 
 }  // namespace net