<rdar://problem/14195566>

Found a race condition when killing an application where the state could be set to exited by the waitpid_thread() _before_ we call task resume (via MachProcess::PrivateResume()) in MachProcess::Kill().


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@185048 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 13 insertions, 9 deletions

diff --git a/tools/debugserver/source/DNB.cpp b/tools/debugserver/source/DNB.cpp
index bcbcf983f..d7955541f 100644
--- a/tools/debugserver/source/DNB.cpp
+++ b/tools/debugserver/source/DNB.cpp
@@ -132,7 +132,7 @@ waitpid_thread (void *arg)
     while (1)
     {
         pid_t child_pid = waitpid(pid, &status, 0);
-        DNBLogThreadedIf(LOG_PROCESS, "waitpid_process_thread (): waitpid (pid = %i, &status, 0) => %i, status = %i, errno = %i", pid, child_pid, status, errno);
+        DNBLogThreadedIf(LOG_PROCESS, "waitpid_thread (): waitpid (pid = %i, &status, 0) => %i, status = %i, errno = %i", pid, child_pid, status, errno);
 
         if (child_pid < 0)
         {
@@ -148,7 +148,7 @@ waitpid_thread (void *arg)
             }
             else// if (WIFEXITED(status) || WIFSIGNALED(status))
             {
-                DNBLogThreadedIf(LOG_PROCESS, "waitpid_process_thread (): setting exit status for pid = %i to %i", child_pid, status);
+                DNBLogThreadedIf(LOG_PROCESS, "waitpid_thread (): setting exit status for pid = %i to %i", child_pid, status);
                 DNBProcessSetExitStatus (child_pid, status);
                 return NULL;
             }
@@ -157,7 +157,7 @@ waitpid_thread (void *arg)
 
     // We should never exit as long as our child process is alive, so if we
     // do something else went wrong and we should exit...
-    DNBLogThreadedIf(LOG_PROCESS, "waitpid_process_thread (): main loop exited, setting exit status to an invalid value (-1) for pid %i", pid);
+    DNBLogThreadedIf(LOG_PROCESS, "waitpid_thread (): main loop exited, setting exit status to an invalid value (-1) for pid %i", pid);
     DNBProcessSetExitStatus (pid, -1);
     return NULL;
 }
diff --git a/tools/debugserver/source/MacOSX/MachProcess.cpp b/tools/debugserver/source/MacOSX/MachProcess.cpp
index 2eab3784e..f6537bfb3 100644
--- a/tools/debugserver/source/MacOSX/MachProcess.cpp
+++ b/tools/debugserver/source/MacOSX/MachProcess.cpp
@@ -268,23 +268,27 @@ MachProcess::SetState(nub_state_t new_state)
         PTHREAD_MUTEX_LOCKER(locker, m_state_mutex);
         const nub_state_t old_state = m_state;
 
-        if (old_state != new_state)
+        if (old_state == eStateExited)
+        {
+            DNBLogThreadedIf(LOG_PROCESS, "MachProcess::SetState(%s) ignoring new state since current state is exited", DNBStateAsString(new_state));
+        }
+        else if (old_state == new_state)
+        {
+            DNBLogThreadedIf(LOG_PROCESS, "MachProcess::SetState(%s) ignoring redundant state change...", DNBStateAsString(new_state));
+        }
+        else
         {
             if (NUB_STATE_IS_STOPPED(new_state))
                 event_mask = eEventProcessStoppedStateChanged;
             else
                 event_mask = eEventProcessRunningStateChanged;
 
-            DNBLogThreadedIf(LOG_PROCESS, "MachProcess::SetState ( old = %s, new = %s ) updating state, event_mask = 0x%8.8x", DNBStateAsString(old_state), DNBStateAsString(new_state), event_mask);
+            DNBLogThreadedIf(LOG_PROCESS, "MachProcess::SetState(%s) upating state (previous state was %s), event_mask = 0x%8.8x", DNBStateAsString(new_state), DNBStateAsString(old_state), event_mask);
 
             m_state = new_state;
             if (new_state == eStateStopped)
                 m_stop_count++;
         }
-        else
-        {
-            DNBLogThreadedIf(LOG_PROCESS, "MachProcess::SetState ( old = %s, new = %s ) ignoring state...", DNBStateAsString(old_state), DNBStateAsString(new_state));
-        }
     }
 
     if (event_mask != 0)