Merge "Fix JDWP Virtualmachine.Resume command"

4 files changed, 62 insertions, 3 deletions

diff --git a/runtime/debugger.cc b/runtime/debugger.cc
index c56c0e94a6..d9061c8e68 100644
--- a/runtime/debugger.cc
+++ b/runtime/debugger.cc
@@ -2391,7 +2391,7 @@ void Dbg::SuspendVM() {
 }
 
 void Dbg::ResumeVM() {
-  Runtime::Current()->GetThreadList()->UndoDebuggerSuspensions();
+  Runtime::Current()->GetThreadList()->ResumeAllForDebugger();
 }
 
 JDWP::JdwpError Dbg::SuspendThread(JDWP::ObjectId thread_id, bool request_suspension) {
diff --git a/runtime/debugger.h b/runtime/debugger.h
index cb7adae47a..48e457fc6f 100644
--- a/runtime/debugger.h
+++ b/runtime/debugger.h
@@ -246,7 +246,9 @@ class Dbg {
    */
   static int64_t LastDebuggerActivity();
 
-  static void UndoDebuggerSuspensions();
+  static void UndoDebuggerSuspensions()
+    LOCKS_EXCLUDED(Locks::thread_list_lock_,
+                   Locks::thread_suspend_count_lock_);
 
   /*
    * Class, Object, Array
@@ -459,7 +461,9 @@ class Dbg {
   static void SuspendVM()
       LOCKS_EXCLUDED(Locks::thread_list_lock_,
                      Locks::thread_suspend_count_lock_);
-  static void ResumeVM();
+  static void ResumeVM()
+      LOCKS_EXCLUDED(Locks::thread_list_lock_,
+                     Locks::thread_suspend_count_lock_);
   static JDWP::JdwpError SuspendThread(JDWP::ObjectId thread_id, bool request_suspension = true)
       LOCKS_EXCLUDED(Locks::mutator_lock_,
                      Locks::thread_list_lock_,
diff --git a/runtime/thread_list.cc b/runtime/thread_list.cc
index 6e189047fe..f8c8fdbfee 100644
--- a/runtime/thread_list.cc
+++ b/runtime/thread_list.cc
@@ -666,6 +666,7 @@ void ThreadList::SuspendAllForDebugger() {
     {
       MutexLock mu(self, *Locks::thread_suspend_count_lock_);
       // Update global suspend all state for attaching threads.
+      DCHECK_GE(suspend_all_count_, debug_suspend_all_count_);
       ++suspend_all_count_;
       ++debug_suspend_all_count_;
       // Increment everybody's suspend count (except our own).
@@ -757,6 +758,55 @@ void ThreadList::SuspendSelfForDebugger() {
   VLOG(threads) << *self << " self-reviving (debugger)";
 }
 
+void ThreadList::ResumeAllForDebugger() {
+  Thread* self = Thread::Current();
+  Thread* debug_thread = Dbg::GetDebugThread();
+  bool needs_resume = false;
+
+  VLOG(threads) << *self << " ResumeAllForDebugger starting...";
+
+  // Threads can't resume if we exclusively hold the mutator lock.
+  Locks::mutator_lock_->AssertNotExclusiveHeld(self);
+
+  {
+    MutexLock mu(self, *Locks::thread_list_lock_);
+    {
+      MutexLock mu(self, *Locks::thread_suspend_count_lock_);
+      // Update global suspend all state for attaching threads.
+      DCHECK_GE(suspend_all_count_, debug_suspend_all_count_);
+      needs_resume = (debug_suspend_all_count_ > 0);
+      if (needs_resume) {
+        --suspend_all_count_;
+        --debug_suspend_all_count_;
+        // Decrement everybody's suspend count (except our own).
+        for (const auto& thread : list_) {
+          if (thread == self || thread == debug_thread) {
+            continue;
+          }
+          if (thread->GetDebugSuspendCount() == 0) {
+            // This thread may have been individually resumed with ThreadReference.Resume.
+            continue;
+          }
+          VLOG(threads) << "requesting thread resume: " << *thread;
+          thread->ModifySuspendCount(self, -1, true);
+        }
+      } else {
+        // We've been asked to resume all threads without being asked to
+        // suspend them all before. Let's print a warning.
+        LOG(WARNING) << "Debugger attempted to resume all threads without "
+                     << "having suspended them all before.";
+      }
+    }
+  }
+
+  if (needs_resume) {
+    MutexLock mu(self, *Locks::thread_suspend_count_lock_);
+    Thread::resume_cond_->Broadcast(self);
+  }
+
+  VLOG(threads) << *self << " ResumeAllForDebugger complete";
+}
+
 void ThreadList::UndoDebuggerSuspensions() {
   Thread* self = Thread::Current();
 
diff --git a/runtime/thread_list.h b/runtime/thread_list.h
index 9f47f9f9ef..a7f2c539af 100644
--- a/runtime/thread_list.h
+++ b/runtime/thread_list.h
@@ -105,6 +105,11 @@ class ThreadList {
   void SuspendSelfForDebugger()
       LOCKS_EXCLUDED(Locks::thread_suspend_count_lock_);
 
+  // Resume all threads
+  void ResumeAllForDebugger()
+      LOCKS_EXCLUDED(Locks::thread_list_lock_,
+                     Locks::thread_suspend_count_lock_);
+
   void UndoDebuggerSuspensions()
       LOCKS_EXCLUDED(Locks::thread_list_lock_,
                      Locks::thread_suspend_count_lock_);