NB: this is an temporary fix, until such time as bug 243935 is fully

resolved.

Add a client request, ANNOTATE_HAPPENS_BEFORE_FORGET_ALL, to notify
Helgrind that it can forget about any h-b edges previously associated
with the specified tag, and release associated resources.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11625

diff --git a/helgrind/helgrind.h b/helgrind/helgrind.h
index 23eb4b70e62403f098857226a275ea888b7c2ae1..cbe09002eb7968e2c3916b7dad1c4e5d5ad66559 100644 (file)
--- a/helgrind/helgrind.h
+++ b/helgrind/helgrind.h
@@ -108,7 +108,7 @@ typedef
       _VG_USERREQ__HG_CLIENTREQ_UNIMP,            /* char* */
       _VG_USERREQ__HG_USERSO_SEND_PRE,        /* arbitrary UWord SO-tag */
       _VG_USERREQ__HG_USERSO_RECV_POST,       /* arbitrary UWord SO-tag */
-      _VG_USERREQ__HG_RESERVED1,              /* Do not use */
+      _VG_USERREQ__HG_USERSO_FORGET_ALL,      /* arbitrary UWord SO-tag */
       _VG_USERREQ__HG_RESERVED2,              /* Do not use */
       _VG_USERREQ__HG_RESERVED3,              /* Do not use */
       _VG_USERREQ__HG_RESERVED4,              /* Do not use */
@@ -458,6 +458,20 @@ typedef
 
    See also, extensive discussion on semantics of this in 
    https://bugs.kde.org/show_bug.cgi?id=243935
+
+   ANNOTATE_HAPPENS_BEFORE_FORGET_ALL(obj) is interim until such time
+   as bug 243935 is fully resolved.  It instructs Helgrind to forget
+   about any ANNOTATE_HAPPENS_BEFORE calls on the specified object, in
+   effect putting it back in its original state.  Once in that state,
+   a use of ANNOTATE_HAPPENS_AFTER on it has no effect on the calling
+   thread.
+
+   An implementation may optionally release resources it has
+   associated with 'obj' when ANNOTATE_HAPPENS_BEFORE_FORGET_ALL(obj)
+   happens.  Users are recommended to use
+   ANNOTATE_HAPPENS_BEFORE_FORGET_ALL to indicate when a
+   synchronisation object is no longer needed, so as to avoid
+   potential indefinite resource leaks.
    ----------------------------------------------------------------
 */
 #define ANNOTATE_HAPPENS_BEFORE(obj) \
@@ -466,6 +480,8 @@ typedef
 #define ANNOTATE_HAPPENS_AFTER(obj) \
    DO_CREQ_v_W(_VG_USERREQ__HG_USERSO_RECV_POST, void*,(obj))
 
+#define ANNOTATE_HAPPENS_BEFORE_FORGET_ALL(obj) \
+   DO_CREQ_v_W(_VG_USERREQ__HG_USERSO_FORGET_ALL, void*,(obj))
 
 /* ----------------------------------------------------------------
    Memory publishing.  The TSan sources say:

diff --git a/helgrind/hg_main.c b/helgrind/hg_main.c
index 74f78fb575079cb5959635e44891809aa646e2cb..a09e18c17af5528fc84359b75892ba78a3706e8a 100644 (file)
--- a/helgrind/hg_main.c
+++ b/helgrind/hg_main.c
@@ -3021,17 +3021,16 @@ static SO* map_usertag_to_SO_lookup_or_alloc ( UWord usertag ) {
    }
 }
 
-// If it's ever needed (XXX check before use)
-//static void map_usertag_to_SO_delete ( UWord usertag ) {
-//   UWord keyW, valW;
-//   map_usertag_to_SO_INIT();
-//   if (VG_(delFromFM)( map_usertag_to_SO, &keyW, &valW, usertag )) {
-//      SO* so = (SO*)valW;
-//      tl_assert(keyW == usertag);
-//      tl_assert(so);
-//      libhb_so_dealloc(so);
-//   }
-//}
+static void map_usertag_to_SO_delete ( UWord usertag ) {
+   UWord keyW, valW;
+   map_usertag_to_SO_INIT();
+   if (VG_(delFromFM)( map_usertag_to_SO, &keyW, &valW, usertag )) {
+      SO* so = (SO*)valW;
+      tl_assert(keyW == usertag);
+      tl_assert(so);
+      libhb_so_dealloc(so);
+   }
+}
 
 
 static
@@ -3090,6 +3089,21 @@ void evh__HG_USERSO_RECV_POST ( ThreadId tid, UWord usertag )
    libhb_so_recv( thr->hbthr, so, True/*strong_recv*/ );
 }
 
+static
+void evh__HG_USERSO_FORGET_ALL ( ThreadId tid, UWord usertag )
+{
+   /* TID declares that any happens-before edges notionally stored in
+      USERTAG can be deleted.  If (as would normally be the case) a
+      SO is associated with USERTAG, then the assocation is removed
+      and all resources associated with SO are freed.  Importantly,
+      that frees up any VTSs stored in SO. */
+   if (SHOW_EVENTS >= 1)
+      VG_(printf)("evh__HG_USERSO_FORGET_ALL(ctid=%d, usertag=%#lx)\n", 
+                  (Int)tid, usertag );
+
+   map_usertag_to_SO_delete( usertag );
+}
+
 
 /*--------------------------------------------------------------*/
 /*--- Lock acquisition order monitoring                      ---*/
@@ -4505,6 +4519,11 @@ Bool hg_handle_client_request ( ThreadId tid, UWord* args, UWord* ret)
          evh__HG_USERSO_RECV_POST( tid, args[1] );
          break;
 
+      case _VG_USERREQ__HG_USERSO_FORGET_ALL:
+         /* UWord arbitrary-SO-tag */
+         evh__HG_USERSO_FORGET_ALL( tid, args[1] );
+         break;
+
       default:
          /* Unhandled Helgrind client request! */
          tl_assert2(0, "unhandled Helgrind client request 0x%lx",