[Lldb-commits] [lldb] r200226 - Fix group stop signal handling issue on Linux.

[Todd Fiala]

Author: tfiala
Date: Mon Jan 27 11:03:57 2014
New Revision: 200226

URL: http://llvm.org/viewvc/llvm-project?rev=200226&view=rev
Log:
Fix group stop signal handling issue on Linux.

This patch addresses a bug where in a multi-threaded program a new
signal from the inferior may be received before all group-stop
messages from an earlier signal have been handled.

Patch by Andrew MacPherson

Modified:
    lldb/trunk/source/Plugins/Process/Linux/ProcessMonitor.cpp

Modified: lldb/trunk/source/Plugins/Process/Linux/ProcessMonitor.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Process/Linux/ProcessMonitor.cpp?rev=200226&r1=200225&r2=200226&view=diff
==============================================================================
--- lldb/trunk/source/Plugins/Process/Linux/ProcessMonitor.cpp (original)
+++ lldb/trunk/source/Plugins/Process/Linux/ProcessMonitor.cpp Mon Jan 27 11:03:57 2014
@@ -1798,14 +1798,23 @@ ProcessMonitor::StopThread(lldb::tid_t t
         int ptrace_err;
         if (!GetSignalInfo(wait_pid, &info, ptrace_err))
         {
-            if (log)
+            // another signal causing a StopAllThreads may have been received
+            // before wait_pid's group-stop was processed, handle it now
+            if (ptrace_err == EINVAL)
             {
-                log->Printf ("ProcessMonitor::%s() GetSignalInfo failed.", __FUNCTION__);
+                assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
 
-                // This would be a particularly interesting case
-                if (ptrace_err == EINVAL)
-                    log->Printf ("ProcessMonitor::%s() in group-stop", __FUNCTION__);
+                if (log)
+                  log->Printf ("ProcessMonitor::%s() resuming from group-stop", __FUNCTION__);
+                // inferior process is in 'group-stop', so deliver SIGSTOP signal
+                if (!Resume(wait_pid, SIGSTOP)) {
+                  assert(0 && "SIGSTOP delivery failed while in 'group-stop' state");
+                }
+                continue;
             }
+
+            if (log)
+                log->Printf ("ProcessMonitor::%s() GetSignalInfo failed.", __FUNCTION__);
             return false;
         }