fellow_cache: Ensure we see seglist loading errors for _iter()

src/fellow_cache.c

@@ -2323,6 +2323,18 @@ fellow_cache_seglists_wait_locked(struct fellow_cache_obj *fco)
 	assert(fco->seglstate == SEGL_DONE || fco->seglstate == SEGL_NEED);
 }
 
+static void
+fellow_cache_seglists_wait(struct fellow_cache_obj *fco)
+{
+
+	CHECK_OBJ_NOTNULL(fco, FELLOW_CACHE_OBJ_MAGIC);
+	if (fco->seglstate != SEGL_LOADING)
+		return;
+	AZ(pthread_mutex_lock(&fco->mtx));
+	fellow_cache_seglists_wait_locked(fco);
+	AZ(pthread_mutex_unlock(&fco->mtx));
+}
+
 /*
  * MEM LAYOUT
  *
@@ -4642,8 +4654,10 @@ fellow_cache_obj_iter(struct fellow_cache *fc, struct fellow_cache_obj *fco,
 	// stack usage
 	assert(readahead <= 31);
 
-	fcr.status = fcr_ok;	// also if func() != 0
-	fcr.r.integer = 0;
+	// fcr_ok is also returned if func() != 0
+	fcr = fco->fcr;
+	if (fcr.status != fcr_ok)
+		return (fcr);
 
 	CHECK_OBJ_NOTNULL(fco, FELLOW_CACHE_OBJ_MAGIC);
 
@@ -4791,7 +4805,14 @@ fellow_cache_obj_iter(struct fellow_cache *fc, struct fellow_cache_obj *fco,
 			fcr.r.integer = ret2;
 	}
 
-	return (fcr);
+	// if ok, wait for seglist loading to complete to see errors
+	if (fcr.status != fcr_ok)
+		fco_latch_err(fco, fcr);
+	else
+		fellow_cache_seglists_wait(fco);
+
+	// to properly return func() return value with fcr_ok
+	return (fco->fcr.status == fcr_ok ? fcr : fco->fcr);
 }
 
 /* Auxiliary attributes
@@ -6653,11 +6674,7 @@ static void test_fellow_cache_obj_iter_final(
 	fc_inj_reset();
 	injcount = -1;
 	AN(injcount);
-	/*
-	 * XXX TEMP BROKEN until
-	 * commit "fellow_cache: Ensure we see seglist loading errors for _iter()"
-	 */
-	while (0 && injcount) {
+	while (injcount) {
 		DBG("injcount %d", injcount);
 
 		fc_inj_set(0);