Avoid gpu watchdog crash on timeout if X is un-responsive.

content/gpu/gpu_watchdog_thread.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.
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "content/gpu/gpu_watchdog_thread.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_util.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/process/process.h"
 #include "build/build_config.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/result_codes.h"
 
 namespace content {
 namespace {
 const int64 kCheckPeriodMs = 2000;
 #if defined(OS_CHROMEOS)
 const base::FilePath::CharType
     kTtyFilePath[] = FILE_PATH_LITERAL("/sys/class/tty/tty0/active");
 #endif
+#if defined(USE_X11)
+const unsigned char text[20] = "check";
+#endif
 }  // namespace
 
 GpuWatchdogThread::GpuWatchdogThread(int timeout)
     : base::Thread("Watchdog"),
       watched_message_loop_(base::MessageLoop::current()),
       timeout_(base::TimeDelta::FromMilliseconds(timeout)),
       armed_(false),
 #if defined(OS_WIN)
       watched_thread_handle_(0),
       arm_cpu_time_(),
 #endif
       task_observer_(this),
       suspended_(false),
+#if defined(USE_X11)
+      display_(NULL),
+      window_(0),
+      atom_(None),
+#endif
       weak_factory_(this) {
   DCHECK(timeout >= 0);
 
 #if defined(OS_WIN)
   // GetCurrentThread returns a pseudo-handle that cannot be used by one thread
   // to identify another. DuplicateHandle creates a "real" handle that can be
   // used for this purpose.
   BOOL result = DuplicateHandle(GetCurrentProcess(),
                                 GetCurrentThread(),
                                 GetCurrentProcess(),
                                 &watched_thread_handle_,
                                 THREAD_QUERY_INFORMATION,
                                 FALSE,
                                 0);
   DCHECK(result);
 #endif
 
 #if defined(OS_CHROMEOS)
   tty_file_ = base::OpenFile(base::FilePath(kTtyFilePath), "r");
 #endif
+#if defined(USE_X11)
+  SetupXServer();
+#endif
   watched_message_loop_->AddTaskObserver(&task_observer_);
 }
 
 void GpuWatchdogThread::PostAcknowledge() {
   // Called on the monitored thread. Responds with OnAcknowledge. Cannot use
   // the method factory. Rely on reference counting instead.
   message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&GpuWatchdogThread::OnAcknowledge, this));
 }
@@ skipping 44 matching lines @@
 
   base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
   if (power_monitor)
     power_monitor->RemoveObserver(this);
 
 #if defined(OS_CHROMEOS)
   if (tty_file_)
     fclose(tty_file_);
 #endif
 
+#if defined(USE_X11)
+  XDestroyWindow(display_, window_);
+  XCloseDisplay(display_);
+#endif
+
   watched_message_loop_->RemoveTaskObserver(&task_observer_);
 }
 
 void GpuWatchdogThread::OnAcknowledge() {
   CHECK(base::PlatformThread::CurrentId() == thread_id());
 
   // The check has already been acknowledged and another has already been
   // scheduled by a previous call to OnAcknowledge. It is normal for a
   // watched thread to see armed_ being true multiple times before
   // the OnAcknowledge task is run on the watchdog thread.
@@ skipping 45 matching lines @@
   // TaskObserver. Any other tasks that are pending on the watched thread will
   // also wake up the observer. This simply ensures there is at least one.
   watched_message_loop_->PostTask(
       FROM_HERE,
       base::Bind(&base::DoNothing));
 
   // Post a task to the watchdog thread to exit if the monitored thread does
   // not respond in time.
   message_loop()->PostDelayedTask(
       FROM_HERE,
-      base::Bind(
-          &GpuWatchdogThread::DeliberatelyTerminateToRecoverFromHang,
-          weak_factory_.GetWeakPtr()),
+      base::Bind(&GpuWatchdogThread::DeliberatelyTerminateToRecoverFromHang,
+                 weak_factory_.GetWeakPtr()),
       timeout);
 }
 
 // Use the --disable-gpu-watchdog command line switch to disable this.
 void GpuWatchdogThread::DeliberatelyTerminateToRecoverFromHang() {
   // Should not get here while the system is suspended.
   DCHECK(!suspended_);
 
 #if defined(OS_WIN)
   // Defer termination until a certain amount of CPU time has elapsed on the
@@ skipping 13 matching lines @@
   // If the watchdog woke up significantly behind schedule, disarm and reset
   // the watchdog check. This is to prevent the watchdog thread from terminating
   // when a machine wakes up from sleep or hibernation, which would otherwise
   // appear to be a hang.
   if (base::Time::Now() > suspension_timeout_) {
     armed_ = false;
     OnCheck(true);
     return;
   }
 
+#if defined(USE_X11)
+  XWindowAttributes attributes;
+  XGetWindowAttributes(display_, window_, &attributes);
+
+  XSelectInput(display_, window_, PropertyChangeMask);
+  SetupXChangeProp();
+
+  XFlush(display_);
+
+  // We wait for the property change event with a timeout. If it arrives we know
+  // that X is responsive and is not the cause of the watchdog trigger, so we
+  // should
+  // terminate. If it times out, it may be due to X taking a long time, but
+  // terminating won't help, so ignore the watchdog trigger.
+  XEvent event_return;
+  base::TimeTicks deadline = base::TimeTicks::Now() + timeout_;
+  while (true) {
+    base::TimeDelta delta = deadline - base::TimeTicks::Now();
+    if (delta < base::TimeDelta()) {
+      return;
+    } else {
+      while (XCheckWindowEvent(display_, window_, PropertyChangeMask,
+                               &event_return)) {
+        if (MatchXEventAtom(&event_return))
+          break;
+      }
+      struct pollfd fds[1];
+      fds[0].fd = XConnectionNumber(display_);
+      fds[0].events = POLLIN;
+      int status = poll(fds, 1, delta.InMilliseconds());
+      if (status == -1) {
+        if (errno == EINTR) {
+          continue;
+        } else {
+          LOG(FATAL) << "Lost X connection, aborting.";
+          break;
+        }
+      } else if (status == 0) {
+        return;
+      } else {
+        continue;
+      }
+    }
+  }
+#endif
+
   // For minimal developer annoyance, don't keep terminating. You need to skip
   // the call to base::Process::Terminate below in a debugger for this to be
   // useful.
   static bool terminated = false;
   if (terminated)
     return;
 
 #if defined(OS_WIN)
   if (IsDebuggerPresent())
     return;
@@ skipping 15 matching lines @@
 
   LOG(ERROR) << "The GPU process hung. Terminating after "
              << timeout_.InMilliseconds() << " ms.";
 
   // Deliberately crash the process to create a crash dump.
   *((volatile int*)0) = 0x1337;
 
   terminated = true;
 }
 
+#if defined(USE_X11)
+void GpuWatchdogThread::SetupXServer() {
+  display_ = XOpenDisplay(NULL);
+  window_ = XCreateWindow(display_, DefaultRootWindow(display_), 0, 0, 1, 1, 0,
+                          CopyFromParent, InputOutput, CopyFromParent, 0, NULL);
+  atom_ = XInternAtom(display_, "CHECK", False);
+}
+
+void GpuWatchdogThread::SetupXChangeProp() {
+  XChangeProperty(display_, window_, atom_, XA_STRING, 8, PropModeReplace, text,
+                  (arraysize(text) - 1));
+}
+
+bool GpuWatchdogThread::MatchXEventAtom(XEvent* event) {
+  if (event->xproperty.window == window_ && event->type == PropertyNotify &&
+      event->xproperty.atom == atom_)
+    return true;
+
+  return false;
+}
+
+#endif
 void GpuWatchdogThread::AddPowerObserver() {
   message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&GpuWatchdogThread::OnAddPowerObserver, this));
 }
 
 void GpuWatchdogThread::OnAddPowerObserver() {
   base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
   DCHECK(power_monitor);
   power_monitor->AddObserver(this);
@@ skipping 42 matching lines @@
   // not increasing. The other is where either the kernel hangs and never
   // returns to user level or where user level code
   // calls into kernel level repeatedly, giving up its quanta before it is
   // tracked, for example a loop that repeatedly Sleeps.
   return base::TimeDelta::FromMilliseconds(static_cast<int64>(
       (user_time64.QuadPart + kernel_time64.QuadPart) / 10000));
 }
 #endif
 
 }  // namespace content