Fix JDWP race at runtime shutdown
When the runtime shuts down, it closes the JDWP connection with the
debugger. However, if a JDWP command is still being processed by the
JDWP handler thread when we close the connection, we won't be able to
send its reply.
Bug: 19628620
Change-Id: I20301325a347d66f3b9ef95ebe8f156abafb1f76
diff --git a/runtime/base/mutex.h b/runtime/base/mutex.h
index 6e7b04f..af00834 100644
--- a/runtime/base/mutex.h
+++ b/runtime/base/mutex.h
@@ -97,6 +97,7 @@
kAllocTrackerLock,
kDeoptimizationLock,
kProfilerLock,
+ kJdwpShutdownLock,
kJdwpEventListLock,
kJdwpAttachLock,
kJdwpStartLock,
diff --git a/runtime/debugger.cc b/runtime/debugger.cc
index a767cf0..c7e3c11 100644
--- a/runtime/debugger.cc
+++ b/runtime/debugger.cc
@@ -307,7 +307,6 @@
// Runtime JDWP state.
static JDWP::JdwpState* gJdwpState = nullptr;
static bool gDebuggerConnected; // debugger or DDMS is connected.
-static bool gDisposed; // debugger called VirtualMachine.Dispose, so we should drop the connection.
static bool gDdmThreadNotification = false;
@@ -319,6 +318,7 @@
static Dbg::HpsgWhat gDdmNhsgWhat;
bool Dbg::gDebuggerActive = false;
+bool Dbg::gDisposed = false;
ObjectRegistry* Dbg::gRegistry = nullptr;
// Recent allocation tracking.
@@ -553,7 +553,7 @@
gJdwpState->PostVMDeath();
}
// Prevent the JDWP thread from processing JDWP incoming packets after we close the connection.
- Disposed();
+ Dispose();
delete gJdwpState;
gJdwpState = nullptr;
delete gRegistry;
@@ -601,14 +601,6 @@
gDisposed = false;
}
-void Dbg::Disposed() {
- gDisposed = true;
-}
-
-bool Dbg::IsDisposed() {
- return gDisposed;
-}
-
bool Dbg::RequiresDeoptimization() {
// We don't need deoptimization if everything runs with interpreter after
// enabling -Xint mode.
diff --git a/runtime/debugger.h b/runtime/debugger.h
index 4f4a781..d1ba6f3 100644
--- a/runtime/debugger.h
+++ b/runtime/debugger.h
@@ -239,7 +239,9 @@
static void GoActive()
LOCKS_EXCLUDED(Locks::breakpoint_lock_, Locks::deoptimization_lock_, Locks::mutator_lock_);
static void Disconnected() LOCKS_EXCLUDED(Locks::deoptimization_lock_, Locks::mutator_lock_);
- static void Disposed();
+ static void Dispose() {
+ gDisposed = true;
+ }
// Returns true if we're actually debugging with a real debugger, false if it's
// just DDMS (or nothing at all).
@@ -255,9 +257,12 @@
// Returns true if a method has any breakpoints.
static bool MethodHasAnyBreakpoints(mirror::ArtMethod* method)
- SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) LOCKS_EXCLUDED(Locks::breakpoint_lock_);
+ SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
+ LOCKS_EXCLUDED(Locks::breakpoint_lock_);
- static bool IsDisposed();
+ static bool IsDisposed() {
+ return gDisposed;
+ }
/*
* Time, in milliseconds, since the last debugger activity. Does not
@@ -756,6 +761,10 @@
// Indicates whether the debugger is making requests.
static bool gDebuggerActive;
+ // Indicates whether we should drop the JDWP connection because the runtime stops or the
+ // debugger called VirtualMachine.Dispose.
+ static bool gDisposed;
+
// The registry mapping objects to JDWP ids.
static ObjectRegistry* gRegistry;
diff --git a/runtime/jdwp/jdwp.h b/runtime/jdwp/jdwp.h
index e16221c..31c9a0b 100644
--- a/runtime/jdwp/jdwp.h
+++ b/runtime/jdwp/jdwp.h
@@ -403,6 +403,14 @@
// Used for VirtualMachine.Exit command handling.
bool should_exit_;
int exit_status_;
+
+ // Used to synchronize runtime shutdown with JDWP command handler thread.
+ // When the runtime shuts down, it needs to stop JDWP command handler thread by closing the
+ // JDWP connection. However, if the JDWP thread is processing a command, it needs to wait
+ // for the command to finish so we can send its reply before closing the connection.
+ Mutex shutdown_lock_ ACQUIRED_AFTER(event_list_lock_);
+ ConditionVariable shutdown_cond_ GUARDED_BY(shutdown_lock_);
+ bool processing_request_ GUARDED_BY(shutdown_lock_);
};
std::string DescribeField(const FieldId& field_id) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
diff --git a/runtime/jdwp/jdwp_handler.cc b/runtime/jdwp/jdwp_handler.cc
index add1394..c711391 100644
--- a/runtime/jdwp/jdwp_handler.cc
+++ b/runtime/jdwp/jdwp_handler.cc
@@ -271,7 +271,7 @@
static JdwpError VM_Dispose(JdwpState*, Request*, ExpandBuf*)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
- Dbg::Disposed();
+ Dbg::Dispose();
return ERR_NONE;
}
diff --git a/runtime/jdwp/jdwp_main.cc b/runtime/jdwp/jdwp_main.cc
index e2b88a5..5b30f0c 100644
--- a/runtime/jdwp/jdwp_main.cc
+++ b/runtime/jdwp/jdwp_main.cc
@@ -126,6 +126,7 @@
*/
ssize_t JdwpNetStateBase::WritePacket(ExpandBuf* pReply, size_t length) {
MutexLock mu(Thread::Current(), socket_lock_);
+ DCHECK(IsConnected()) << "Connection with debugger is closed";
DCHECK_LE(length, expandBufGetLength(pReply));
return TEMP_FAILURE_RETRY(write(clientSock, expandBufGetBuffer(pReply), length));
}
@@ -140,6 +141,7 @@
ssize_t JdwpNetStateBase::WriteBufferedPacketLocked(const std::vector<iovec>& iov) {
socket_lock_.AssertHeld(Thread::Current());
+ DCHECK(IsConnected()) << "Connection with debugger is closed";
return TEMP_FAILURE_RETRY(writev(clientSock, &iov[0], iov.size()));
}
@@ -225,7 +227,10 @@
jdwp_token_owner_thread_id_(0),
ddm_is_active_(false),
should_exit_(false),
- exit_status_(0) {
+ exit_status_(0),
+ shutdown_lock_("JDWP shutdown lock", kJdwpShutdownLock),
+ shutdown_cond_("JDWP shutdown condition variable", shutdown_lock_),
+ processing_request_(false) {
}
/*
@@ -338,10 +343,20 @@
JdwpState::~JdwpState() {
if (netState != nullptr) {
/*
- * Close down the network to inspire the thread to halt.
+ * Close down the network to inspire the thread to halt. If a request is being processed,
+ * we need to wait for it to finish first.
*/
- VLOG(jdwp) << "JDWP shutting down net...";
- netState->Shutdown();
+ {
+ Thread* self = Thread::Current();
+ MutexLock mu(self, shutdown_lock_);
+ while (processing_request_) {
+ VLOG(jdwp) << "JDWP command in progress: wait for it to finish ...";
+ shutdown_cond_.Wait(self);
+ }
+
+ VLOG(jdwp) << "JDWP shutting down net...";
+ netState->Shutdown();
+ }
if (debug_thread_started_) {
run = false;
@@ -369,7 +384,13 @@
// Returns "false" if we encounter a connection-fatal error.
bool JdwpState::HandlePacket() {
- JdwpNetStateBase* netStateBase = reinterpret_cast<JdwpNetStateBase*>(netState);
+ Thread* const self = Thread::Current();
+ {
+ MutexLock mu(self, shutdown_lock_);
+ processing_request_ = true;
+ }
+ JdwpNetStateBase* netStateBase = netState;
+ CHECK(netStateBase != nullptr) << "Connection has been closed";
JDWP::Request request(netStateBase->input_buffer_, netStateBase->input_count_);
ExpandBuf* pReply = expandBufAlloc();
@@ -388,6 +409,11 @@
}
expandBufFree(pReply);
netStateBase->ConsumeBytes(request.GetLength());
+ {
+ MutexLock mu(self, shutdown_lock_);
+ processing_request_ = false;
+ shutdown_cond_.Broadcast(self);
+ }
return true;
}
