Close a race where VCL tries to modify the obj.ttl at the same moment

the grim reaper has taken the object off the binheap to inspect it.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@3565 d4fa192b-c00b-0410-8231-f00ffab90ce4

diff --git a/varnish-cache/bin/varnishd/cache_expire.c b/varnish-cache/bin/varnishd/cache_expire.c
index f533505f6ee7a2b4be9e4ce374b95fa722fb655e..d03515212762bc932c6c11c957eeb7b883ddd5cd 100644 (file)
--- a/varnish-cache/bin/varnishd/cache_expire.c
+++ b/varnish-cache/bin/varnishd/cache_expire.c
@@ -143,6 +143,7 @@ update_object_when(const struct object *o)
        CHECK_OBJ_NOTNULL(o, OBJECT_MAGIC);
        oe = o->objexp;
        CHECK_OBJ_NOTNULL(oe, OBJEXP_MAGIC);
+       Lck_AssertHeld(&exp_mtx);
 
        if (o->prefetch < 0.0) {
                when = o->ttl + o->prefetch;
@@ -184,8 +185,9 @@ EXP_Insert(struct object *o)
 
        assert(o->entered != 0 && !isnan(o->entered));
        oe->lru_stamp = o->entered;
-       (void)update_object_when(o);
        Lck_Lock(&exp_mtx);
+       assert(oe->timer_idx == BINHEAP_NOIDX);
+       (void)update_object_when(o);
        binheap_insert(exp_heap, oe);
        assert(oe->timer_idx != BINHEAP_NOIDX);
        VTAILQ_INSERT_TAIL(&lru, oe, list);
@@ -245,7 +247,11 @@ EXP_Rearm(const struct object *o)
                return;
        CHECK_OBJ_NOTNULL(oe, OBJEXP_MAGIC);
        Lck_Lock(&exp_mtx);
-       if (update_object_when(o)) {
+       /*
+        * The hang-man might have this object of the binheap while
+        * tending to a timer.  If so, we do not muck with it here.
+        */
+       if (oe->timer_idx != BINHEAP_NOIDX && update_object_when(o)) {
                /*
                 * XXX: this could possibly be optimized by shuffling
                 * XXX: up or down, but that leaves some very nasty
@@ -332,8 +338,9 @@ exp_timer(void *arg)
                                WSL(&ww, SLT_Debug, 0, "Attempt Prefetch %u",
                                    o->xid);
                        }
-                       (void)update_object_when(o);
                        Lck_Lock(&exp_mtx);
+                       assert(oe->timer_idx == BINHEAP_NOIDX);
+                       (void)update_object_when(o);
                        binheap_insert(exp_heap, oe);
                        assert(oe->timer_idx != BINHEAP_NOIDX);
                        Lck_Unlock(&exp_mtx);
@@ -347,6 +354,7 @@ exp_timer(void *arg)
                        WSL(&ww, SLT_ExpKill, 0,
                            "%u %d", o->xid, (int)(o->ttl - t));
                        Lck_Lock(&exp_mtx);
+                       assert(oe->timer_idx == BINHEAP_NOIDX);
                        VTAILQ_REMOVE(&lru, o->objexp, list);
                        oe->on_lru = 0;
                        VSL_stats->n_expired++;