Complement VDP error handling

* remember push errors in the context
* also fail additional pushes once we saw an error

Try to fail requests as early as possible. Otherwise just calling VDP
functions after an error is a noop.

Fixes #2618

bin/varnishd/cache/cache_deliver_proc.c

@@ -73,7 +73,7 @@ VDP_bytes(struct req *req, enum vdp_action act, const void *ptr, ssize_t len)
 	return (vdc->retval);
 }
 
-void
+int
 VDP_push(struct req *req, const struct vdp *vdp, void *priv, int bottom)
 {
 	struct vdp_entry *vdpe;
@@ -85,12 +85,18 @@ VDP_push(struct req *req, const struct vdp *vdp, void *priv, int bottom)
 	AN(vdp->name);
 	AN(vdp->func);
 
+	if (vdc->retval)
+		return (vdc->retval);
+
 	if (DO_DEBUG(DBG_PROCESSORS))
 		VSLb(req->vsl, SLT_Debug, "VDP_push(%s)", vdp->name);
 
 	vdpe = WS_Alloc(req->ws, sizeof *vdpe);
-	if (vdpe == NULL)
-		return;
+	if (vdpe == NULL) {
+		AZ(vdc->retval);
+		vdc->retval = -1;
+		return (vdc->retval);
+	}
 	INIT_OBJ(vdpe, VDP_ENTRY_MAGIC);
 	vdpe->vdp = vdp;
 	vdpe->priv = priv;
@@ -100,7 +106,9 @@ VDP_push(struct req *req, const struct vdp *vdp, void *priv, int bottom)
 		VTAILQ_INSERT_HEAD(&vdc->vdp, vdpe, list);
 	vdc->nxt = VTAILQ_FIRST(&vdc->vdp);
 
-	AZ(vdpe->vdp->func(req, VDP_INIT, &vdpe->priv, NULL, 0));
+	AZ(vdc->retval);
+	vdc->retval = vdpe->vdp->func(req, VDP_INIT, &vdpe->priv, NULL, 0);
+	return (vdc->retval);
 }
 
 void
@@ -113,10 +121,15 @@ VDP_close(struct req *req)
 	vdc = req->vdc;
 	while (!VTAILQ_EMPTY(&vdc->vdp)) {
 		vdpe = VTAILQ_FIRST(&vdc->vdp);
-		CHECK_OBJ_NOTNULL(vdpe, VDP_ENTRY_MAGIC);
-		VTAILQ_REMOVE(&vdc->vdp, vdpe, list);
-		AZ(vdpe->vdp->func(req, VDP_FINI, &vdpe->priv, NULL, 0));
-		AZ(vdpe->priv);
+		if (vdc->retval >= 0)
+			AN(vdpe);
+		if (vdpe != NULL) {
+			CHECK_OBJ_NOTNULL(vdpe, VDP_ENTRY_MAGIC);
+			VTAILQ_REMOVE(&vdc->vdp, vdpe, list);
+			AZ(vdpe->vdp->func(req, VDP_FINI, &vdpe->priv,
+			    NULL, 0));
+			AZ(vdpe->priv);
+		}
 		vdc->nxt = VTAILQ_FIRST(&vdc->vdp);
 	}
 }

bin/varnishd/cache/cache_esi_deliver.c

@@ -815,9 +815,9 @@ ved_deliver(struct req *req, struct boc *boc, int wantbody)
 		ved_stripgzip(req, boc);
 	} else {
 		if (ecx->isgzip && !i)
-			VDP_push(req, &ved_vdp_pgz, ecx, 1);
+			(void)VDP_push(req, &ved_vdp_pgz, ecx, 1);
 		else
-			VDP_push(req, &ved_ved, ecx->preq, 1);
+			(void)VDP_push(req, &ved_ved, ecx->preq, 1);
 		(void)VDP_DeliverObj(req);
 		(void)VDP_bytes(req, VDP_FLUSH, NULL, 0);
 	}

bin/varnishd/cache/cache_filter.h

@@ -121,8 +121,8 @@ struct vdp_ctx {
 #define VDP_CTX_MAGIC		0xee501df7
 	struct vdp_entry_s	vdp;
 	struct vdp_entry	*nxt;
-	unsigned		retval;
+	int			retval;
 };
 
 int VDP_bytes(struct req *, enum vdp_action act, const void *ptr, ssize_t len);
-void VDP_push(struct req *, const struct vdp *, void *priv, int bottom);
+int VDP_push(struct req *, const struct vdp *, void *priv, int bottom);

bin/varnishd/cache/cache_range.c

@@ -175,7 +175,8 @@ vrg_dorange(struct req *req, const char *r)
 	vrg_priv->range_off = 0;
 	vrg_priv->range_low = low;
 	vrg_priv->range_high = high + 1;
-	VDP_push(req, &vrg_vdp, vrg_priv, 1);
+	if (VDP_push(req, &vrg_vdp, vrg_priv, 1))
+		return ("WS too small");
 	http_PutResponse(req->resp, "HTTP/1.1", 206, NULL);
 	return (NULL);
 }

bin/varnishd/cache/cache_req_fsm.c

@@ -342,7 +342,7 @@ cnt_transmit(struct worker *wrk, struct req *req)
 	struct boc *boc;
 	const char *r;
 	uint16_t status;
-	int sendbody;
+	int err, sendbody;
 	intmax_t clval;
 
 	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
@@ -375,15 +375,18 @@ cnt_transmit(struct worker *wrk, struct req *req)
 	} else
 		sendbody = 1;
 
+	err = 0;
 	if (sendbody >= 0) {
 		if (!req->disable_esi && req->resp_len != 0 &&
-		    ObjHasAttr(wrk, req->objcore, OA_ESIDATA))
-			VDP_push(req, &VDP_esi, NULL, 0);
+		    ObjHasAttr(wrk, req->objcore, OA_ESIDATA) &&
+		    VDP_push(req, &VDP_esi, NULL, 0) < 0)
+			err++;
 
 		if (cache_param->http_gzip_support &&
 		    ObjCheckFlag(req->wrk, req->objcore, OF_GZIPED) &&
-		    !RFC2616_Req_Gzip(req->http))
-			VDP_push(req, &VDP_gunzip, NULL, 1);
+		    !RFC2616_Req_Gzip(req->http) &&
+		    VDP_push(req, &VDP_gunzip, NULL, 1) < 0)
+			err++;
 
 		if (cache_param->http_range_support &&
 		    http_IsStatus(req->resp, 200)) {
@@ -405,7 +408,12 @@ cnt_transmit(struct worker *wrk, struct req *req)
 			    "Content-Length: %jd", req->resp_len);
 	}
 
-	req->transport->deliver(req, boc, sendbody);
+	if (err == 0)
+		req->transport->deliver(req, boc, sendbody);
+	else {
+		VSLb(req->vsl, SLT_Error, "Failure to push processors");
+		req->doclose = SC_OVERLOAD;
+	}
 
 	VSLb_ts_req(req, "Resp", W_TIM_real(wrk));
 

bin/varnishd/http1/cache_http1_deliver.c

@@ -128,8 +128,11 @@ V1D_Deliver(struct req *req, struct boc *boc, int sendbody)
 	if (req->resp_len == 0)
 		sendbody = 0;
 
-	if (sendbody)
-		VDP_push(req, &v1d_vdp, NULL, 1);
+	if (sendbody && VDP_push(req, &v1d_vdp, NULL, 1)) {
+		v1d_error(req, "workspace_thread overflow");
+		AZ(req->wrk->v1l);
+		return;
+	}
 
 	AZ(req->wrk->v1l);
 	V1L_Open(req->wrk, req->wrk->aws,

bin/varnishd/http2/cache_http2_deliver.c

@@ -265,10 +265,13 @@ h2_deliver(struct req *req, struct boc *boc, int sendbody)
 
 	WS_Release(req->ws, 0);
 
-	if (sendbody) {
-		VDP_push(req, &h2_vdp, NULL, 1);
+	/* XXX someone into H2 please add appropriate error handling */
+	while (sendbody) {
+		err = VDP_push(req, &h2_vdp, NULL, 1);
+		if (err)
+			break;
 		err = VDP_DeliverObj(req);
-		/*XXX*/(void)err;
+		break;
 	}
 
 	AZ(req->wrk->v1l);

bin/varnishtest/tests/r02618.vtc

+varnishtest "sweep through tight client workspace conditions in deliver"
+
+server s1 {
+	rxreq
+	txresp -hdr "Cache-Control: mag-age=3600" -bodylen 1024
+} -start
+
+varnish v1 -vcl+backend {
+	import vtc;
+	import std;
+	sub vcl_recv {
+		return (hash);
+	}
+	sub vcl_deliver {
+		vtc.workspace_alloc(client, -4 *
+			(std.integer(req.xid, 1001) - 1001) / 2);
+	}
+} -start
+
+client c1 -repeat 100 {
+	txreq -url "/"
+	# some responses will fail (503), some won't. All we care
+	# about here is the fact that we don't panic
+	rxresp
+} -run