[Lldb-commits] [lldb] r211636 - Rework fix in r201744. You really DO need to waitpid twice to get the

[Jim Ingham]

Author: jingham
Date: Tue Jun 24 16:51:42 2014
New Revision: 211636

URL: http://llvm.org/viewvc/llvm-project?rev=211636&view=rev
Log:
Rework fix in r201744.  You really DO need to waitpid twice to get the
process fully reaped.  The race & bad behavior was because we were letting
the reaping thread in LLDB to also set the Process exit status, so debugserver
would sometimes be shut down before it got a chance to report the exit status, 
and then we got confused.

<rdar://problem/16555850>

Modified:
    lldb/trunk/include/lldb/Target/Process.h
    lldb/trunk/include/lldb/lldb-enumerations.h
    lldb/trunk/source/Host/macosx/Host.mm
    lldb/trunk/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
    lldb/trunk/tools/debugserver/source/DNB.cpp

Modified: lldb/trunk/include/lldb/Target/Process.h
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Target/Process.h?rev=211636&r1=211635&r2=211636&view=diff
==============================================================================
--- lldb/trunk/include/lldb/Target/Process.h (original)
+++ lldb/trunk/include/lldb/Target/Process.h Tue Jun 24 16:51:42 2014
@@ -824,9 +824,6 @@ public:
     bool
     MonitorProcess () const
     {
-        if (GetFlags().Test(lldb::eLaunchFlagsDontMonitorProcess))
-            return true;
-        
         if (m_monitor_callback && ProcessIDIsValid())
         {
             Host::StartMonitoringChildProcess (m_monitor_callback,

Modified: lldb/trunk/include/lldb/lldb-enumerations.h
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/lldb-enumerations.h?rev=211636&r1=211635&r2=211636&view=diff
==============================================================================
--- lldb/trunk/include/lldb/lldb-enumerations.h (original)
+++ lldb/trunk/include/lldb/lldb-enumerations.h Tue Jun 24 16:51:42 2014
@@ -47,8 +47,8 @@ namespace lldb {
         eLaunchFlagLaunchInTTY  = (1u << 5),  ///< Launch the process in a new TTY if supported by the host 
         eLaunchFlagLaunchInShell= (1u << 6),   ///< Launch the process inside a shell to get shell expansion
         eLaunchFlagLaunchInSeparateProcessGroup = (1u << 7), ///< Launch the process in a separate process group
-        eLaunchFlagsDontMonitorProcess = (1u << 8)  ///< If you are going to hand the process off (e.g. to debugserver)
-                                                    ///< set this flag so lldb & the handee don't race to reap it.
+        eLaunchFlagsDontSetExitStatus = (1u << 8)  ///< If you are going to hand the process off (e.g. to debugserver)
+                                                    ///< set this flag so lldb & the handee don't race to set its exit status.
     } LaunchFlags;
         
     //----------------------------------------------------------------------

Modified: lldb/trunk/source/Host/macosx/Host.mm
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Host/macosx/Host.mm?rev=211636&r1=211635&r2=211636&view=diff
==============================================================================
--- lldb/trunk/source/Host/macosx/Host.mm (original)
+++ lldb/trunk/source/Host/macosx/Host.mm Tue Jun 24 16:51:42 2014
@@ -1667,7 +1667,12 @@ Host::LaunchProcess (ProcessLaunchInfo &
         if (!launch_info.MonitorProcess())
         {
             const bool monitor_signals = false;
-            StartMonitoringChildProcess (Process::SetProcessExitStatus, 
+            Host::MonitorChildProcessCallback callback = nullptr;
+            
+            if (!launch_info.GetFlags().Test(lldb::eLaunchFlagsDontSetExitStatus))
+                callback = Process::SetProcessExitStatus;
+
+            StartMonitoringChildProcess (callback,
                                          NULL, 
                                          pid, 
                                          monitor_signals);

Modified: lldb/trunk/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp?rev=211636&r1=211635&r2=211636&view=diff
==============================================================================
--- lldb/trunk/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp (original)
+++ lldb/trunk/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp Tue Jun 24 16:51:42 2014
@@ -785,10 +785,10 @@ PlatformDarwin::DebugProcess (ProcessLau
     
     if (IsHost())
     {
-        // We are going to hand this process off to debugserver which will monitor the process itself.
-        // So don't also monitor it from lldb or we set up a race between debugserver & us for who will find out
-        // about the debugged process's death.
-        launch_info.GetFlags().Set(eLaunchFlagsDontMonitorProcess);
+        // We are going to hand this process off to debugserver which will be in charge of setting the exit status.
+        // We still need to reap it from lldb but if we let the monitor thread also set the exit status, we set up a
+        // race between debugserver & us for who will find out about the debugged process's death.
+        launch_info.GetFlags().Set(eLaunchFlagsDontSetExitStatus);
         process_sp = Platform::DebugProcess (launch_info, debugger, target, listener, error);
     }
     else

Modified: lldb/trunk/tools/debugserver/source/DNB.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/tools/debugserver/source/DNB.cpp?rev=211636&r1=211635&r2=211636&view=diff
==============================================================================
--- lldb/trunk/tools/debugserver/source/DNB.cpp (original)
+++ lldb/trunk/tools/debugserver/source/DNB.cpp Tue Jun 24 16:51:42 2014
@@ -239,7 +239,7 @@ spawn_kqueue_thread (pid_t pid)
 
     struct kevent reg_event;
     
-    EV_SET(&reg_event, pid, EVFILT_PROC, EV_ADD, NOTE_EXIT|NOTE_EXIT_DETAIL, 0, NULL);
+    EV_SET(&reg_event, pid, EVFILT_PROC, EV_ADD, NOTE_EXIT|NOTE_EXITSTATUS|NOTE_EXIT_DETAIL, 0, NULL);
     // Register the event:
     int result = kevent (kq_id, &reg_event, 1, NULL, 0, NULL);
     if (result != 0)