[Windows, Process] Fix an issue in windows thread handling that was causing LLDB to hang
Summary: The function ResumeThread on Windows returns a DWORD which is an unsigned int. In TargetThreadWindows::DoResume, there's code that determines how many times to call ResumeThread based on whether the return value is greater than 0. Since the function returns -1 (as an unsigned int) on failure, this was getting stuck in an infinite loop if ResumeThread failed for any reason. The correct thing to do is check whether the return value is -1 and then return the appropriate error instead of ignoring the return value.
Reviewers: asmith, zturner, labath
Reviewed By: zturner
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D47020
llvm-svn: 332670
diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index ea919d5..13b8a49 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -349,13 +349,23 @@
LLDB_LOG(log, "resuming {0} threads.", m_thread_list.GetSize());
+ bool failed = false;
for (uint32_t i = 0; i < m_thread_list.GetSize(); ++i) {
auto thread = std::static_pointer_cast<TargetThreadWindows>(
m_thread_list.GetThreadAtIndex(i));
- thread->DoResume();
+ Status result = thread->DoResume();
+ if (result.Fail()) {
+ failed = true;
+ LLDB_LOG(log, "Trying to resume thread at index {0}, but failed with error {1}.", i, result);
+ }
}
- SetPrivateState(eStateRunning);
+ if (failed) {
+ error.SetErrorString("ProcessWindows::DoResume failed");
+ return error;
+ } else {
+ SetPrivateState(eStateRunning);
+ }
} else {
LLDB_LOG(log, "error: process %I64u is in state %u. Returning...",
m_session_data->m_debugger->GetProcess().GetProcessId(),
diff --git a/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp b/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp
index a4d6030..3341451 100644
--- a/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp
@@ -98,11 +98,11 @@
return m_unwinder_ap.get();
}
-bool TargetThreadWindows::DoResume() {
+Status TargetThreadWindows::DoResume() {
StateType resume_state = GetTemporaryResumeState();
StateType current_state = GetState();
if (resume_state == current_state)
- return true;
+ return Status();
if (resume_state == eStateStepping) {
uint32_t flags_index =
@@ -118,8 +118,16 @@
DWORD previous_suspend_count = 0;
HANDLE thread_handle = m_host_thread.GetNativeThread().GetSystemHandle();
do {
+ // ResumeThread returns -1 on error, or the thread's *previous* suspend count on success.
+ // This means that the return value is 1 when the thread was restarted.
+ // Note that DWORD is an unsigned int, so we need to explicitly compare with -1.
previous_suspend_count = ::ResumeThread(thread_handle);
- } while (previous_suspend_count > 0);
+
+ if (previous_suspend_count == (DWORD)-1)
+ return Status(::GetLastError(), eErrorTypeWin32);
+
+ } while (previous_suspend_count > 1);
}
- return true;
+
+ return Status();
}
diff --git a/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.h b/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.h
index 8b4e3df..7b93952 100644
--- a/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.h
+++ b/lldb/source/Plugins/Process/Windows/Common/TargetThreadWindows.h
@@ -37,7 +37,7 @@
bool CalculateStopInfo() override;
Unwind *GetUnwinder() override;
- bool DoResume();
+ Status DoResume();
HostThread GetHostThread() const { return m_host_thread; }