1 files changed, 12 insertions, 6 deletions
diff --git a/lldb/source/Host/posix/HostThreadPosix.cpp b/lldb/source/Host/posix/HostThreadPosix.cpp
index 9c489243193..3ac83ac07b1 100644
--- a/lldb/source/Host/posix/HostThreadPosix.cpp
+++ b/lldb/source/Host/posix/HostThreadPosix.cpp
@@ -53,13 +53,16 @@ Error
 HostThreadPosix::Cancel()
 {
     Error error;
+    if (IsJoinable())
+    {
 #ifndef __ANDROID__
-    int err = ::pthread_cancel(m_thread);
-    error.SetError(err, eErrorTypePOSIX);
+        assert(false && "someone is calling HostThread::Cancel()");
+        int err = ::pthread_cancel(m_thread);
+        error.SetError(err, eErrorTypePOSIX);
 #else
-    error.SetErrorString("HostThreadPosix::Cancel() not supported on Android");
+        error.SetErrorString("HostThreadPosix::Cancel() not supported on Android");
 #endif
-
+    }
     return error;
 }
 
@@ -67,8 +70,11 @@ Error
 HostThreadPosix::Detach()
 {
     Error error;
-    int err = ::pthread_detach(m_thread);
-    error.SetError(err, eErrorTypePOSIX);
+    if (IsJoinable())
+    {
+        int err = ::pthread_detach(m_thread);
+        error.SetError(err, eErrorTypePOSIX);
+    }
     Reset();
     return error;
 }