Simplify memory handling around struct h2h_decode

Since we verify that header blocks are not interleaved, and we zero the
struct h2h_decode on every new header block, there is no need to malloc
a separate struct h2h_decode per stream.

bin/varnishd/http2/cache_http2.h

@@ -127,7 +127,6 @@ struct h2_req {
 	VTAILQ_ENTRY(h2_req)		list;
 	int64_t				t_window;
 	int64_t				r_window;
-	struct h2h_decode		*decode;
 
 	/* Where to wake this stream up */
 	struct worker			*wrk;
@@ -161,6 +160,7 @@ struct h2_sess {
 	struct ws			*ws;
 	struct http_conn		*htc;
 	struct vsl_log			*vsl;
+	struct h2h_decode		*decode;
 	struct vht_table		dectbl[1];
 
 	unsigned			rxf_len;
@@ -208,10 +208,10 @@ struct h2h_decode {
 	struct vhd_decode		vhd[1];
 };
 
-void h2h_decode_init(const struct h2_sess *h2, struct h2h_decode *d);
-h2_error h2h_decode_fini(const struct h2_sess *h2, struct h2h_decode *d);
-h2_error h2h_decode_bytes(struct h2_sess *h2, struct h2h_decode *d,
-    const uint8_t *ptr, size_t len);
+void h2h_decode_init(const struct h2_sess *h2);
+h2_error h2h_decode_fini(const struct h2_sess *h2);
+h2_error h2h_decode_bytes(struct h2_sess *h2, const uint8_t *ptr,
+    size_t len);
 
 /* cache_http2_send.c */
 void H2_Send_Get(struct worker *, struct h2_sess *, struct h2_req *);

bin/varnishd/http2/cache_http2_hpack.c

@@ -164,13 +164,15 @@ h2h_addhdr(struct http *hp, char *b, size_t namelen, size_t len)
 }
 
 void
-h2h_decode_init(const struct h2_sess *h2, struct h2h_decode *d)
+h2h_decode_init(const struct h2_sess *h2)
 {
+	struct h2h_decode *d;
 
 	CHECK_OBJ_NOTNULL(h2, H2_SESS_MAGIC);
 	CHECK_OBJ_NOTNULL(h2->new_req, REQ_MAGIC);
 	CHECK_OBJ_NOTNULL(h2->new_req->http, HTTP_MAGIC);
-	AN(d);
+	AN(h2->decode);
+	d = h2->decode;
 	INIT_OBJ(d, H2H_DECODE_MAGIC);
 	VHD_Init(d->vhd);
 	d->out_l = WS_Reserve(h2->new_req->http->ws, 0);
@@ -189,11 +191,13 @@ h2h_decode_init(const struct h2_sess *h2, struct h2h_decode *d)
  * is a stream level error.
  */
 h2_error
-h2h_decode_fini(const struct h2_sess *h2, struct h2h_decode *d)
+h2h_decode_fini(const struct h2_sess *h2)
 {
 	h2_error ret;
+	struct h2h_decode *d;
 
 	CHECK_OBJ_NOTNULL(h2, H2_SESS_MAGIC);
+	d = h2->decode;
 	CHECK_OBJ_NOTNULL(h2->new_req, REQ_MAGIC);
 	CHECK_OBJ_NOTNULL(d, H2H_DECODE_MAGIC);
 	WS_ReleaseP(h2->new_req->http->ws, d->out);
@@ -217,10 +221,10 @@ h2h_decode_fini(const struct h2_sess *h2, struct h2h_decode *d)
  * H2E_PROTOCOL_ERROR: Malformed header or duplicate pseudo-header.
  */
 h2_error
-h2h_decode_bytes(struct h2_sess *h2, struct h2h_decode *d,
-    const uint8_t *in, size_t in_l)
+h2h_decode_bytes(struct h2_sess *h2, const uint8_t *in, size_t in_l)
 {
 	struct http *hp;
+	struct h2h_decode *d;
 	size_t in_u = 0;
 
 	CHECK_OBJ_NOTNULL(h2, H2_SESS_MAGIC);
@@ -229,6 +233,7 @@ h2h_decode_bytes(struct h2_sess *h2, struct h2h_decode *d,
 	CHECK_OBJ_NOTNULL(hp, HTTP_MAGIC);
 	CHECK_OBJ_NOTNULL(hp->ws, WS_MAGIC);
 	AN(hp->ws->r);
+	d = h2->decode;
 	CHECK_OBJ_NOTNULL(d, H2H_DECODE_MAGIC);
 
 	/* Only H2E_ENHANCE_YOUR_CALM indicates that we should continue

bin/varnishd/http2/cache_http2_proto.c

@@ -225,10 +225,8 @@ h2_kill_req(struct worker *wrk, const struct h2_sess *h2,
 			AZ(pthread_cond_signal(r2->cond));
 		r2 = NULL;
 	} else {
-		if (r2->state == H2_S_OPEN && r2->decode != NULL) {
-			(void)h2h_decode_fini(h2, r2->decode);
-			FREE_OBJ(r2->decode);
-		}
+		if (r2->state == H2_S_OPEN && h2->new_req == r2->req)
+			(void)h2h_decode_fini(h2);
 	}
 	Lck_Unlock(&h2->sess->mtx);
 	if (r2 != NULL)
@@ -557,8 +555,7 @@ h2_end_headers(struct worker *wrk, struct h2_sess *h2,
 
 	ASSERT_RXTHR(h2);
 	assert(r2->state == H2_S_OPEN);
-	h2e = h2h_decode_fini(h2, r2->decode);
-	FREE_OBJ(r2->decode);
+	h2e = h2h_decode_fini(h2);
 	h2->new_req = NULL;
 	if (r2->req->req_body_status == REQ_BODY_NONE) {
 		/* REQ_BODY_NONE implies one of the frames in the
@@ -650,9 +647,7 @@ h2_rx_headers(struct worker *wrk, struct h2_sess *h2, struct h2_req *r2)
 	HTTP_Setup(req->http, req->ws, req->vsl, SLT_ReqMethod);
 	http_SetH(req->http, HTTP_HDR_PROTO, "HTTP/2.0");
 
-	ALLOC_OBJ(r2->decode, H2H_DECODE_MAGIC);
-	AN(r2->decode);
-	h2h_decode_init(h2, r2->decode);
+	h2h_decode_init(h2);
 
 	p = h2->rxf_data;
 	l = h2->rxf_len;
@@ -668,13 +663,12 @@ h2_rx_headers(struct worker *wrk, struct h2_sess *h2, struct h2_req *r2)
 		l -= 5;
 		p += 5;
 	}
-	h2e = h2h_decode_bytes(h2, r2->decode, p, l);
+	h2e = h2h_decode_bytes(h2, p, l);
 	if (h2e != NULL) {
 		Lck_Lock(&h2->sess->mtx);
 		VSLb(h2->vsl, SLT_Debug, "HPACK(hdr) %s", h2e->name);
 		Lck_Unlock(&h2->sess->mtx);
-		(void)h2h_decode_fini(h2, r2->decode);
-		FREE_OBJ(r2->decode);
+		(void)h2h_decode_fini(h2);
 		AZ(r2->req->ws->r);
 		h2_del_req(wrk, r2);
 		return (h2e);
@@ -700,14 +694,13 @@ h2_rx_continuation(struct worker *wrk, struct h2_sess *h2, struct h2_req *r2)
 	if (r2 == NULL || r2->state != H2_S_OPEN || r2->req != h2->new_req)
 		return (H2CE_PROTOCOL_ERROR);	// XXX spec ?
 	req = r2->req;
-	h2e = h2h_decode_bytes(h2, r2->decode, h2->rxf_data, h2->rxf_len);
+	h2e = h2h_decode_bytes(h2, h2->rxf_data, h2->rxf_len);
 	r2->req->acct.req_hdrbytes += h2->rxf_len;
 	if (h2e != NULL) {
 		Lck_Lock(&h2->sess->mtx);
 		VSLb(h2->vsl, SLT_Debug, "HPACK(cont) %s", h2e->name);
 		Lck_Unlock(&h2->sess->mtx);
-		(void)h2h_decode_fini(h2, r2->decode);
-		FREE_OBJ(r2->decode);
+		(void)h2h_decode_fini(h2);
 		AZ(r2->req->ws->r);
 		h2_del_req(wrk, r2);
 		return (h2e);

bin/varnishd/http2/cache_http2_session.c

@@ -97,7 +97,7 @@ h2_local_settings(struct h2_settings *h2s)
 
 static struct h2_sess *
 h2_init_sess(const struct worker *wrk, struct sess *sp,
-    struct h2_sess *h2s, struct req *srq)
+    struct h2_sess *h2s, struct req *srq, struct h2h_decode *decode)
 {
 	uintptr_t *up;
 	struct h2_sess *h2;
@@ -128,6 +128,7 @@ h2_init_sess(const struct worker *wrk, struct sess *sp,
 		VTAILQ_INIT(&h2->txqueue);
 		h2_local_settings(&h2->local_settings);
 		h2->remote_settings = H2_proto_settings;
+		h2->decode = decode;
 
 		AZ(VHT_Init(h2->dectbl,
 			h2->local_settings.header_table_size));
@@ -338,6 +339,7 @@ h2_new_session(struct worker *wrk, void *arg)
 	struct h2_req *r2, *r22;
 	int again;
 	uint8_t settings[48];
+	struct h2h_decode decode;
 	size_t l;
 
 	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
@@ -350,7 +352,7 @@ h2_new_session(struct worker *wrk, void *arg)
 	assert (req->err_code == H2_PU_MARKER || req->err_code == H2_OU_MARKER);
 
 	h2 = h2_init_sess(wrk, sp, &h2s,
-	    req->err_code == H2_PU_MARKER ? req : NULL);
+	    req->err_code == H2_PU_MARKER ? req : NULL, &decode);
 	h2->req0 = h2_new_req(wrk, h2, 0, NULL);
 	AZ(h2->htc->priv);
 	h2->htc->priv = h2;