[Lldb-commits] [PATCH] D12968: Fix for lldb-mi crash in Listener code if -exec-abort MI command was invoked without getting process stopped

Tue Sep 29 11:05:49 PDT 2015

KLapshin updated this revision to Diff 36005.
KLapshin added a comment.

I realized what m_events.empty check in Listener::FindNextEventInternal() method returned event collection is NOT empty - probably because list.empty() just compare begin != end pointers, but pointers may be absolutely invalid.

So, as another workaround - switch to m_events.size() == 0 check.

I know - this looks funny because list.size() has O(N) complexity - i.e. - linear and time consuming, but works in this case because it do real empty list check.

I consider latest diff at moment just as some hint.

Actually two threads may modify events collection - one associated with Process and another one with GDBProcess module.

Full log (process and events) below corresponding to m_events.empty replaced with m_events collection size checking:

  0x7f9f3d535110 Listener::WaitForEventsInternal (timeout = { 0x0 }) for lldb.process.internal_state_listener
  -exec-abort
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::HijackBroadcaster (listener("lldb.process.halt_listener")=0x7fff5ac24580)
  Process::SetPrivateState (stopped)
  0x7fff5ac24580 Listener::WaitForEventsInternal (timeout = { 0x7fff5ac244e0 }) for lldb.process.halt_listener
  Process::SetPrivateState (stopped) stop_id = 16
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::BroadcastEvent (event_sp = {0x7f9f39f16ff0 Event: broadcaster = 0x7f9f3d534fa0 (lldb.process.internal_state_broadcaster), type = 0x00000001, data = { process = 0x7f9f3d534e00 (pid = 258), state = stopped}}, unique =0) hijack = 0x7fff5ac24580
  0x7fff5ac24580 Listener('lldb.process.halt_listener')::AddEvent (event_sp = {0x7f9f39f16ff0})
  0x7f9f3d536660 Listener::WaitForEventsInternal (timeout = { 0x0 }) for lldb.process.gdb-remote.async-listener
  0x7fff5ac24580 'lldb.process.halt_listener' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f39f16ff0
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::RestoreBroadcaster (about to pop listener("lldb.process.halt_listener")=0x7fff5ac24580)
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::BroadcastEvent (event_sp = {0x7f9f39f16ff0 Event: broadcaster = 0x7f9f3d534fa0 (lldb.process.internal_state_broadcaster), type = 0x00000001, data = { process = 0x7f9f3d534e00 (pid = 258), state = stopped}}, unique =0) hijack = 0x0
  0x7f9f3d535110 Listener('lldb.process.internal_state_listener')::AddEvent (event_sp = {0x7f9f39f16ff0})
  0x7f9f3d535110 'lldb.process.internal_state_listener' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f39f16ff0
  Process::StopForDestroyOrDetach() About to stop.
  0x700000428840 Listener::StartListeningForEvents (broadcaster = 0x7f9f3d5356a0, mask = 0x00000020) acquired_mask = 0x00000020 for Communication::SyncronizeWithReadThread
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::BroadcastEvent (event_sp = {0x7f9f39e16fa0 Event: broadcaster = 0x7f9f3d534fa0 (lldb.process.internal_state_broadcaster), type = 0x00000002, data = <NULL>}, unique =0) hijack = 0x0
  0x7f9f3d535110 Listener('lldb.process.internal_state_listener')::AddEvent (event_sp = {0x7f9f39e16fa0})
  Process::WaitForProcessToStop (timeout = 0x7fff5ac25b40)
  Process::WaitForStateChangedEvents (timeout = 0x7fff5ac25b40, event_sp)...
  0x7f9f3b0ed920 Listener::WaitForEventsInternal (timeout = { 0x7fff5ac25b40 }) for
  0x7f9f3b0ed920 Listener::WaitForEventsInternal() unknown error for
  Process::WaitForStateChangedEvents (timeout = 0x7fff5ac25b40, event_sp) => invalid
  Process::StopForDestroyOrDetach() failed to stop, state is: invalid
  0x7f9f3d535db8 Broadcaster("gdb-remote.client")::HijackBroadcaster (listener("lldb.NotifyHijacker")=0x109d0bfa8)
  Process::ShouldBroadcastEvent (0x7f9f39f16ff0) stopped due to an interrupt, state: stopped
  Process::ShouldBroadcastEvent (0x7f9f39f16ff0) => new state: stopped, last broadcast state: stopped - YES
  Process::HandlePrivateEvent (pid = 258) broadcasting new state stopped (old state running) to public
  0x7f9f3d534e38 Broadcaster("lldb.process")::BroadcastEvent (event_sp = {0x7f9f39f16ff0 Event: broadcaster = 0x7f9f3d534e38 (lldb.process), type = 0x00000001 (state-changed), data = { process = 0x7f9f3d534e00 (pid = 258), state = stopped}}, unique =0) hijack = 0x0
  0x7f9f3a058278 Listener('lldb.Debugger')::AddEvent (event_sp = {0x7f9f39f16ff0})
  Process::WaitForEventsPrivate (timeout = 0x0, event_sp)...
  0x7f9f3d535110 Listener::WaitForEventsInternal (timeout = { 0x0 }) for lldb.process.internal_state_listener
  0x7f9f3d535110 'lldb.process.internal_state_listener' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f39e16fa0
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::HijackBroadcaster (listener("lldb.process.halt_listener")=0x700000428aa0)
  0x700000428aa0 Listener::WaitForEventsInternal (timeout = { 0x700000428a00 }) for lldb.process.halt_listener
  0x7f9f3a058278 'lldb.Debugger' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f39f16ff0
  Process::SetPublicState (state = stopped, restarted = 0)
  Process::SetPublicState (stopped) -- unlocking run lock
  0x7f9f3d535db8 Broadcaster("gdb-remote.client")::RestoreBroadcaster (about to pop listener("lldb.NotifyHijacker")=0x109d0bfa8)
  Process::SetExitStatus (status=9 (0x00000009), description="")
  Process::SetPrivateState (exited)
  Process::SetPrivateState (exited) stop_id = 17
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::BroadcastEvent (event_sp = {0x7f9f39f0e470 Event: broadcaster = 0x7f9f3d534fa0 (lldb.process.internal_state_broadcaster), type = 0x00000001, data = { process = 0x7f9f3d534e00 (pid = 258), state = exited}}, unique =0) hijack = 0x700000428aa0
  0x700000428aa0 Listener('lldb.process.halt_listener')::AddEvent (event_sp = {0x7f9f39f0e470})
  0x700000428aa0 'lldb.process.halt_listener' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f39f0e470
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::RestoreBroadcaster (about to pop listener("lldb.process.halt_listener")=0x700000428aa0)
  0x7f9f3d534fa0 Broadcaster("lldb.process.internal_state_broadcaster")::BroadcastEvent (event_sp = {0x7f9f39f0e470 Event: broadcaster = 0x7f9f3d534fa0 (lldb.process.internal_state_broadcaster), type = 0x00000001, data = { process = 0x7f9f3d534e00 (pid = 258), state = exited}}, unique =0) hijack = 0x0
  0x7f9f3d535110 Listener('lldb.process.internal_state_listener')::AddEvent (event_sp = {0x7f9f39f0e470})
  0x7f9f3d5365a8 Broadcaster("lldb.process.gdb-remote.async-broadcaster")::BroadcastEvent (event_sp = {0x7f9f3b026b80 Event: broadcaster = 0x7f9f3d5365a8 (lldb.process.gdb-remote.async-broadcaster), type = 0x00000002 (async thread should exit), data = <NULL>}, unique =0) hijack = 0x0
  Process::WaitForEventsPrivate (timeout = 0x0, event_sp)...
  0x7f9f3d535110 Listener::WaitForEventsInternal (timeout = { 0x0 }) for lldb.process.internal_state_listener
  0x7f9f3d535110 'lldb.process.internal_state_listener' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f39f0e470
  0x700000428840 Listener::StartListeningForEvents (broadcaster = 0x7f9f3d5356a0, mask = 0x00000020) acquired_mask = 0x00000020 for Communication::SyncronizeWithReadThread
  Process::ShouldBroadcastEvent (0x7f9f39f0e470) => new state: exited, last broadcast state: exited - YES
  Process::HandlePrivateEvent (pid = 258) broadcasting new state exited (old state stopped) to public
  0x7f9f3d536660 Listener('lldb.process.gdb-remote.async-listener')::AddEvent (event_sp = {0x7f9f3b026b80})
  0x7f9f3d534e38 Broadcaster("lldb.process")::BroadcastEvent (event_sp = {0x7f9f39f0e470 Event: broadcaster = 0x7f9f3d534e38 (lldb.process), type = 0x00000001 (state-changed), data = { process = 0x7f9f3d534e00 (pid = 258), state = exited}}, unique =0) hijack = 0x0
  0x7f9f3a058278 Listener('lldb.Debugger')::AddEvent (event_sp = {0x7f9f39f0e470})
  0x7f9f3d536660 'lldb.process.gdb-remote.async-listener' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f3b026b80
  Went to stop the private state thread, but it was already invalid.
  ^done
  (gdb)
  =thread-exited,id="1",group-id="i1"
  =thread-exited,id="2",group-id="i1"
  =thread-exited,id="3",group-id="i1"
  =thread-exited,id="4",group-id="i1"
  =thread-exited,id="5",group-id="i1"
  =thread-exited,id="6",group-id="i1"
  =thread-exited,id="7",group-id="i1"
  (gdb)
  0x7f9f3a058278 'lldb.Debugger' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=0) event 0x7f9f39f0e470
  0x7f9f3a058278 'lldb.Debugger' Listener::FindNextEventInternal(broadcaster=0x0, broadcaster_names=0x0[0], event_type_mask=0x00000000, remove=1) event 0x7f9f39f0e470
  Process::SetPublicState (state = exited, restarted = 0)
  (gdb)
  =thread-exited,id="1",group-id="i1"
  =thread-group-exited,id="i1",exit-code="0"
  *stopped,reason="exited-normally"
  (gdb)


Repository:
  rL LLVM

http://reviews.llvm.org/D12968

Files:
  source/Core/Listener.cpp

Index: source/Core/Listener.cpp
===================================================================

--- source/Core/Listener.cpp
+++ source/Core/Listener.cpp
@@ -281,7 +281,7 @@
 
     Mutex::Locker lock(m_events_mutex);
 
-    if (m_events.empty())
+    if (!m_events.size())
         return false;
 
 


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