From: dsmith <dsmith>
Date: Mon, 19 Mar 2007 21:14:21 +0000 (+0000)
Subject: 2007-03-19  David Smith  <dsmith@redhat.com>
X-Git-Tag: release-0.5.13~14
X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=ab655cf8ec35ab47a38d95182dfe07a0e380681a;p=systemtap.git

2007-03-19  David Smith  <dsmith@redhat.com>

	PR 4146 (partial fix)
	* tapsets.cxx (all_session_groups): Added note about stating that
	begin probes should be registered (actually run) first and end
	probes should be unregistered (run) last.
	* translate.cxx (c_unparser::emit_module_exit): Process probe
	group vector in reverse order so that probe groups will get
	unregistered in the reverse order that they were registered.
---

diff --git a/ChangeLog b/ChangeLog
index f81d6e15e..19318d357 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2007-03-19  David Smith  <dsmith@redhat.com>
+
+	PR 4146 (partial fix)
+	* tapsets.cxx (all_session_groups): Added note about stating that
+	begin probes should be registered (actually run) first and end
+	probes should be unregistered (run) last.
+	* translate.cxx (c_unparser::emit_module_exit): Process probe
+	group vector in reverse order so that probe groups will get
+	unregistered in the reverse order that they were registered.
+
 2007-03-19  Frank Ch. Eigler  <fche@elastic.org>
 
 	* buildrun.cxx (compile_pass): Emit kbuild-time autoconf widgets
diff --git a/tapsets.cxx b/tapsets.cxx
index 54388f5be..eb66f2bc2 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -5419,6 +5419,13 @@ all_session_groups(systemtap_session& s)
 {
   vector<derived_probe_group*> g;
 #define DOONE(x) if (s. x##_derived_probes) g.push_back (s. x##_derived_probes)
+
+  // Note that order *is* important here.  We want to make sure we
+  // register (actually run) begin probes before any other probe type
+  // is run.  Similarly, when unregistering probes, we want to
+  // unregister (actually run) end probes after every other probe type
+  // has be unregistered.  To do the latter,
+  // c_unparser::emit_module_exit() will run this list backwards.
   DOONE(be);
   DOONE(dwarf);
   DOONE(timer);
diff --git a/translate.cxx b/translate.cxx
index 365303738..89a961e31 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -1201,9 +1201,13 @@ c_unparser::emit_module_exit ()
   // XXX: might like to have an escape hatch, in case some probe is
   // genuinely stuck somehow
 
+  // Notice we're processing the derived_probe_group list in reverse
+  // order.  This ensures that probes get unregistered in reverse
+  // order of the way they were registered.
   vector<derived_probe_group*> g = all_session_groups (*session);
-  for (unsigned i=0; i<g.size(); i++)
-    g[i]->emit_module_exit (*session); // NB: runs "end" probes
+  for (vector<derived_probe_group*>::reverse_iterator i = g.rbegin();
+       i != g.rend(); i++)
+    (*i)->emit_module_exit (*session); // NB: runs "end" probes
 
   for (unsigned i=0; i<session->globals.size(); i++)
     {