CLEANUP: quic: improve naming for rxbuf/datagrams handling

QUIC datagrams are read from a random thread. They are then redispatch
to the connection thread according to the first packet DCID. These
operations are implemented through a special buffer designed to avoid
locking.

Refactor this code with the following changes :
* <rxbuf> type is renamed <quic_receiver_buf>. Its list element is also
  renamed to highligh its attach point to a receiver.
* <quic_dgram> and <quic_receiver_buf> definition are moved to
  quic_sock-t.h. This helps to reduce the size of quic_conn-t.h.
* <quic_dgram> list elements are renamed to highlight their attach point
  into a <quic_receiver_buf> and a <quic_dghdlr>.

This should be backported up to 2.6.

include/haproxy/quic_conn-t.h

@@ -377,8 +377,9 @@ struct quic_dgram {
 	struct sockaddr_storage saddr;
 	struct sockaddr_storage daddr;
 	struct quic_conn *qc;
-	struct list list;
+
-	struct mt_list mt_list;
+	struct list recv_list; /* elemt to quic_receiver_buf <dgram_list>. */
+	struct mt_list handler_list; /* elem to quic_dghdlr <dgrams>. */
 };
 
 /* The QUIC packet numbers are 62-bits integers */
@@ -578,13 +579,6 @@ struct qring {
 	struct mt_list mt_list;
 };
 
-/* QUIC RX buffer */
-struct rxbuf {
-	struct buffer buf;
-	struct list dgrams;
-	struct mt_list mt_list;
-};
-
 /* Status of the connection/mux layer. This defines how to handle app data.
  *
  * During a standard quic_conn lifetime it transitions like this :

include/haproxy/quic_sock-t.h

@@ -8,5 +8,14 @@ struct quic_accept_queue {
 	struct tasklet *tasklet;  /* task responsible to call listener_accept */
 };
 
+/* Buffer used to receive QUIC datagrams on random thread and redispatch them
+ * to the connection thread.
+ */
+struct quic_receiver_buf {
+	struct buffer buf; /* storage for datagrams received. */
+	struct list dgram_list; /* datagrams received with this rxbuf. */
+	struct mt_list rxbuf_el; /* list element into receiver.rxbuf_list. */
+};
+
 #endif /* USE_QUIC */
 #endif /* _HAPROXY_QUIC_SOCK_T_H */

include/haproxy/receiver-t.h

@@ -65,7 +65,7 @@ struct receiver {
 	struct rx_settings *settings;    /* points to the settings used by this receiver */
 	struct list proto_list;          /* list in the protocol header */
 #ifdef USE_QUIC
-	struct mt_list rxbuf_list;       /* The same as ->rxbufs but arranged in a list */
+	struct mt_list rxbuf_list;       /* list of buffers to receive and dispatch QUIC datagrams. */
 #endif
 	/* warning: this struct is huge, keep it at the bottom */
 	struct sockaddr_storage addr;    /* the address the socket is bound to */

src/proto_quic.c

@@ -538,14 +538,14 @@ static void quic_add_listener(struct protocol *proto, struct listener *listener)
 static int quic_alloc_rxbufs_listener(struct listener *l)
 {
 	int i;
-	struct rxbuf *rxbuf;
+	struct quic_receiver_buf *tmp;
 
 	MT_LIST_INIT(&l->rx.rxbuf_list);
 	for (i = 0; i < global.nbthread; i++) {
+		struct quic_receiver_buf *rxbuf;
 		char *buf;
-		struct rxbuf *rxbuf;
 
-		rxbuf = calloc(1, sizeof *rxbuf);
+		rxbuf = calloc(1, sizeof(*rxbuf));
 		if (!rxbuf)
 			goto err;
 
@@ -556,16 +556,16 @@ static int quic_alloc_rxbufs_listener(struct listener *l)
 		}
 
 		rxbuf->buf = b_make(buf, QUIC_RX_BUFSZ, 0, 0);
-		LIST_INIT(&rxbuf->dgrams);
+		LIST_INIT(&rxbuf->dgram_list);
-		MT_LIST_APPEND(&l->rx.rxbuf_list, &rxbuf->mt_list);
+		MT_LIST_APPEND(&l->rx.rxbuf_list, &rxbuf->rxbuf_el);
 	}
 
 	return 1;
 
  err:
-	while ((rxbuf = MT_LIST_POP(&l->rx.rxbuf_list, typeof(rxbuf), mt_list))) {
+	while ((tmp = MT_LIST_POP(&l->rx.rxbuf_list, typeof(tmp), rxbuf_el))) {
-		pool_free(pool_head_quic_rxbuf, rxbuf->buf.area);
+		pool_free(pool_head_quic_rxbuf, tmp->buf.area);
-		free(rxbuf);
+		free(tmp);
 	}
 	return 0;
 }

src/quic_conn.c

@@ -7160,7 +7160,7 @@ struct task *quic_lstnr_dghdlr(struct task *t, void *ctx, unsigned int state)
 
 	TRACE_ENTER(QUIC_EV_CONN_LPKT);
 
-	while ((dgram = MT_LIST_POP(&dghdlr->dgrams, typeof(dgram), mt_list))) {
+	while ((dgram = MT_LIST_POP(&dghdlr->dgrams, typeof(dgram), handler_list))) {
 		pos = dgram->buf;
 		end = pos + dgram->len;
 		do {

src/quic_sock.c

@@ -268,8 +268,10 @@ static int quic_lstnr_dgram_dispatch(unsigned char *buf, size_t len, void *owner
 	dgram->saddr = *saddr;
 	dgram->daddr = *daddr;
 	dgram->qc = NULL;
-	LIST_APPEND(dgrams, &dgram->list);
+
-	MT_LIST_APPEND(&quic_dghdlrs[cid_tid].dgrams, &dgram->mt_list);
+	/* Attached datagram to its quic_receiver_buf and quic_dghdlrs. */
+	LIST_APPEND(dgrams, &dgram->recv_list);
+	MT_LIST_APPEND(&quic_dghdlrs[cid_tid].dgrams, &dgram->handler_list);
 
 	/* typically quic_lstnr_dghdlr() */
 	tasklet_wakeup(quic_dghdlrs[cid_tid].task);
@@ -392,7 +394,7 @@ static ssize_t quic_recv(int fd, void *out, size_t len,
 void quic_sock_fd_iocb(int fd)
 {
 	ssize_t ret;
-	struct rxbuf *rxbuf;
+	struct quic_receiver_buf *rxbuf;
 	struct buffer *buf;
 	struct listener *l = objt_listener(fdtab[fd].owner);
 	struct quic_transport_params *params;
@@ -412,7 +414,7 @@ void quic_sock_fd_iocb(int fd)
 	if (!(fdtab[fd].state & FD_POLL_IN) || !fd_recv_ready(fd))
 		return;
 
-	rxbuf = MT_LIST_POP(&l->rx.rxbuf_list, typeof(rxbuf), mt_list);
+	rxbuf = MT_LIST_POP(&l->rx.rxbuf_list, typeof(rxbuf), rxbuf_el);
 	if (!rxbuf)
 		goto out;
 
@@ -460,7 +462,7 @@ void quic_sock_fd_iocb(int fd)
 		/* Append this datagram only to the RX buffer list. It will
 		 * not be treated by any datagram handler.
 		 */
-		LIST_APPEND(&rxbuf->dgrams, &dgram->list);
+		LIST_APPEND(&rxbuf->dgram_list, &dgram->recv_list);
 
 		/* Consume the remaining space */
 		b_add(buf, cspace);
@@ -478,7 +480,7 @@ void quic_sock_fd_iocb(int fd)
 
 	b_add(buf, ret);
 	if (!quic_lstnr_dgram_dispatch(dgram_buf, ret, l, &saddr, &daddr,
-	                               new_dgram, &rxbuf->dgrams)) {
+	                               new_dgram, &rxbuf->dgram_list)) {
 		/* If wrong, consume this datagram */
 		b_del(buf, ret);
 	}
@@ -487,7 +489,7 @@ void quic_sock_fd_iocb(int fd)
 		goto start;
  out:
 	pool_free(pool_head_quic_dgram, new_dgram);
-	MT_LIST_APPEND(&l->rx.rxbuf_list, &rxbuf->mt_list);
+	MT_LIST_APPEND(&l->rx.rxbuf_list, &rxbuf->rxbuf_el);
 }
 
 /* Send a datagram stored into <buf> buffer with <sz> as size.