2007-03-21 David Smith <dsmith@redhat.com>

	PR 4146
	* tapsets.cxx (common_probe_entryfn_prologue): Added
	'interruptible' parameter.  If a probe is interruptible,
	interrupts are not disabled while the probe executes.  Preemption
	is disabled however.  Interruptible parameter defaults to false.
	(common_probe_entryfn_epilogue): Ditto.
	(be_derived_probe_group::emit_module_decl): Uses new
	'interruptible' parameter to mark begin/end probes as
	interruptible.
	(probe_derived_probe_group::emit_module): Initialize
	'actionremaining' with MAXACTION instead of initializing
	'actioncount' with 0.
	* translate.cxx (emit_common_header): Renamed 'actioncount' to
	'actionremaining'.  Turned logic around to initialize
	actionremaining to MAXACTION or MAXACTION_INTERRUPTIBLE then
	decrement it as actions occur.
	(translate_pass): Added MAXACTION_INTERRUPTIBLE initialization.
	* translate.h: Removed outdated comment portion.
	* stap.1.in: Documented MAXACTION_INTERRUPTIBLE.
	* NEWS: Added note about begin/end probes being run with
	interrupts enabled.

1 files changed, 23 insertions, 11 deletions

diff --git a/tapsets.cxx b/tapsets.cxx
index 78d47dc7..0dddc33a 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -129,10 +129,12 @@ be_derived_probe::join_group (systemtap_session& s)
 // ------------------------------------------------------------------------
 void
 common_probe_entryfn_prologue (translator_output* o, string statestr,
-			       bool overload_processing = true)
+			       bool overload_processing = true,
+			       bool interruptible = false)
 {
   o->newline() << "struct context* __restrict__ c;";
-  o->newline() << "unsigned long flags;";
+  if (! interruptible)
+    o->newline() << "unsigned long flags;";
 
   if (overload_processing)
     o->newline() << "#if defined(STP_TIMING) || defined(STP_OVERLOAD)";
@@ -150,7 +152,10 @@ common_probe_entryfn_prologue (translator_output* o, string statestr,
   o->newline() << "static int _pfm_num_pmd_x;";
 #endif
 
-  o->newline() << "local_irq_save (flags);";
+  if (! interruptible)
+    o->newline() << "local_irq_save (flags);";
+  else
+    o->newline() << "preempt_disable ();";
 
   // Check for enough free enough stack space
   o->newline() << "if (unlikely ((((unsigned long) (& c)) & (THREAD_SIZE-1))"; // free space
@@ -185,7 +190,10 @@ common_probe_entryfn_prologue (translator_output* o, string statestr,
   o->newline() << "c->regs = 0;";
   o->newline() << "c->pi = 0;";
   o->newline() << "c->probe_point = 0;";
-  o->newline() << "c->actioncount = 0;";
+  if (! interruptible)
+    o->newline() << "c->actionremaining = MAXACTION;";
+  else
+    o->newline() << "c->actionremaining = MAXACTION_INTERRUPTIBLE;";
   o->newline() << "#ifdef STP_TIMING";
   o->newline() << "c->statp = 0;";
   o->newline() << "#endif";
@@ -194,7 +202,8 @@ common_probe_entryfn_prologue (translator_output* o, string statestr,
 
 void
 common_probe_entryfn_epilogue (translator_output* o,
-			       bool overload_processing = true)
+			       bool overload_processing = true,
+			       bool interruptible = false)
 {
   if (overload_processing)
     o->newline() << "#if defined(STP_TIMING) || defined(STP_OVERLOAD)";
@@ -262,7 +271,10 @@ common_probe_entryfn_epilogue (translator_output* o,
   o->newline(-1) << "probe_epilogue:"; // context is free
   o->indent(1);
 
-  o->newline() << "local_irq_restore (flags);";
+  if (! interruptible)
+    o->newline() << "local_irq_restore (flags);";
+  else
+    o->newline() << "preempt_enable_no_resched ();";
 }
 
 
@@ -276,17 +288,17 @@ be_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "/* ---- begin/end probes ---- */";
   s.op->newline() << "void enter_begin_probe (void (*fn)(struct context*)) {";
   s.op->indent(1);
-  common_probe_entryfn_prologue (s.op, "STAP_SESSION_STARTING", false);
+  common_probe_entryfn_prologue (s.op, "STAP_SESSION_STARTING", false, true);
   s.op->newline() << "c->probe_point = \"begin\";";
   s.op->newline() << "(*fn) (c);";
-  common_probe_entryfn_epilogue (s.op, false);
+  common_probe_entryfn_epilogue (s.op, false, true);
   s.op->newline(-1) << "}";
   s.op->newline() << "void enter_end_probe (void (*fn)(struct context*)) {";
   s.op->indent(1);
-  common_probe_entryfn_prologue (s.op, "STAP_SESSION_STOPPING", false);
+  common_probe_entryfn_prologue (s.op, "STAP_SESSION_STOPPING", false, true);
   s.op->newline() << "c->probe_point = \"end\";";
   s.op->newline() << "(*fn) (c);";
-  common_probe_entryfn_epilogue (s.op, false);
+  common_probe_entryfn_epilogue (s.op, false, true);
   s.op->newline(-1) << "}";
 }
 
@@ -4130,7 +4142,7 @@ profile_derived_probe_group::emit_module_decls (systemtap_session& s)
         {
           // Some lightweight inter-probe context resetting 
           // XXX: not quite right: MAXERRORS not respected
-          s.op->newline() << "c->actioncount = 0;";
+          s.op->newline() << "c->actionremaining = MAXACTION;";
         }
       s.op->newline() << "if (c->last_error == NULL) " << probes[i]->name << " (c);";
     }