5fd24c673e
The following situation occured if we were stopping a process (due to breakpoint, watchpoint, ... hit) while a new thread was being created. - process has two threads: A and B. - thread A hits a breakpoint: we send a STOP signal to thread B and register a callback with ThreadStateCoordinator to send a stop notification after the thread stops. - thread B stops, but not due to the SIGSTOP, but on a thread creation event (of a new thread C). We are unaware of our desire to stop, so we queue ThreadStopped and RequestResume operations with TSC, so the thread can continue running. - TSC receives the ThreadStopped event, sees that all threads are stopped and fires the delayed stop notification. - immediately after that TSC gets the RequestResume operation, so it resumes the thread. At this point the state is inconsistent because LLDB thinks the process is stopped and will start issuing commands to it, but one of the threads is in fact running. Things eventually break. I address this problem by omitting the two TSC events altogether and Resuming the thread B directly. This way the short stop is invisible to the TSC and the delayed notification will not fire. We will fire the notification when we actually process the SIGSTOP on thread B. When we get the initial SIGSTOP for thread C, we also resume the thread and send a ThreadWasCreated message (is_stopped = false) to the TSC. This way, the TSC can stop the thread on its own and handle the stop event later. This way the state of the new thread is correctly handled as well (thanks Chaoren for the idea). This patch also removes the synchronisation between the thread creation notifications on threads B and C. The need for this synchronisation is unclear (the comments seem to hint that the new thread is "fully created" only after we process both events, but I have noticed no regressions in treating it as "created" even after just processing the initial C event), but it is a source for many kinds of obscure races, since it introduces a new thread state "Launching" and the rest of the code does not handle this state at all (what happens if we get a resume request from LLDB while this thread is launching? what happens if we get a stop request? etc.). This fixes the "spurious $O packet" problem in TestPrintStackTraces.py. However, the test remains disabled on i386 due to the VDSO issue. Test Plan: TestPrintStackTraces works on x86_64. No regressions in the rest of the test suite. Reviewers: vharron, chaoren Subscribers: lldb-commits Differential Revision: http://reviews.llvm.org/D9145 llvm-svn: 235579
119 lines
3.3 KiB
C++
119 lines
3.3 KiB
C++
//===-- NativeThreadLinux.h ----------------------------------- -*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef liblldb_NativeThreadLinux_H_
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#define liblldb_NativeThreadLinux_H_
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#include "lldb/lldb-private-forward.h"
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#include "lldb/Host/common/NativeThreadProtocol.h"
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#include <map>
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#include <string>
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namespace lldb_private {
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namespace process_linux {
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class NativeProcessLinux;
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class NativeThreadLinux : public NativeThreadProtocol
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{
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friend class NativeProcessLinux;
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public:
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NativeThreadLinux (NativeProcessLinux *process, lldb::tid_t tid);
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// ---------------------------------------------------------------------
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// NativeThreadProtocol Interface
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// ---------------------------------------------------------------------
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std::string
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GetName() override;
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lldb::StateType
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GetState () override;
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bool
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GetStopReason (ThreadStopInfo &stop_info, std::string& description) override;
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NativeRegisterContextSP
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GetRegisterContext () override;
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Error
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SetWatchpoint (lldb::addr_t addr, size_t size, uint32_t watch_flags, bool hardware) override;
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Error
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RemoveWatchpoint (lldb::addr_t addr) override;
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private:
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// ---------------------------------------------------------------------
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// Interface for friend classes
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// ---------------------------------------------------------------------
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void
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SetRunning ();
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void
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SetStepping ();
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void
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SetStoppedBySignal (uint32_t signo);
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/// Return true if the thread is stopped.
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/// If stopped by a signal, indicate the signo in the signo argument.
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/// Otherwise, return LLDB_INVALID_SIGNAL_NUMBER.
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bool
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IsStopped (int *signo);
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void
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SetStoppedByExec ();
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void
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SetStoppedByBreakpoint ();
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void
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SetStoppedByWatchpoint (uint32_t wp_index);
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bool
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IsStoppedAtBreakpoint ();
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bool
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IsStoppedAtWatchpoint ();
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void
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SetStoppedByTrace ();
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void
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SetCrashedWithException (const siginfo_t& info);
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void
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SetSuspended ();
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void
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SetExited ();
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// ---------------------------------------------------------------------
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// Private interface
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// ---------------------------------------------------------------------
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void
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MaybeLogStateChange (lldb::StateType new_state);
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// ---------------------------------------------------------------------
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// Member Variables
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// ---------------------------------------------------------------------
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lldb::StateType m_state;
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ThreadStopInfo m_stop_info;
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NativeRegisterContextSP m_reg_context_sp;
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std::string m_stop_description;
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using WatchpointIndexMap = std::map<lldb::addr_t, uint32_t>;
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WatchpointIndexMap m_watchpoint_index_map;
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};
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} // namespace process_linux
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} // namespace lldb_private
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#endif // #ifndef liblldb_NativeThreadLinux_H_
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