selftests/net: add zerocopy support for PF_RDS test case

Send a cookie with sendmsg() on PF_RDS sockets, and process the
returned batched cookies in do_recv_completion()
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/net/msg_zerocopy.c

@@ -168,17 +168,39 @@ static int do_accept(int fd)
 	return fd;
 }
 
-static bool do_sendmsg(int fd, struct msghdr *msg, bool do_zerocopy)
+static void add_zcopy_cookie(struct msghdr *msg, uint32_t cookie)
+{
+	struct cmsghdr *cm;
+
+	if (!msg->msg_control)
+		error(1, errno, "NULL cookie");
+	cm = (void *)msg->msg_control;
+	cm->cmsg_len = CMSG_LEN(sizeof(cookie));
+	cm->cmsg_level = SOL_RDS;
+	cm->cmsg_type = RDS_CMSG_ZCOPY_COOKIE;
+	memcpy(CMSG_DATA(cm), &cookie, sizeof(cookie));
+}
+
+static bool do_sendmsg(int fd, struct msghdr *msg, bool do_zerocopy, int domain)
 {
 	int ret, len, i, flags;
+	static uint32_t cookie;
+	char ckbuf[CMSG_SPACE(sizeof(cookie))];
 
 	len = 0;
 	for (i = 0; i < msg->msg_iovlen; i++)
 		len += msg->msg_iov[i].iov_len;
 
 	flags = MSG_DONTWAIT;
-	if (do_zerocopy)
+	if (do_zerocopy) {
 		flags |= MSG_ZEROCOPY;
+		if (domain == PF_RDS) {
+			memset(&msg->msg_control, 0, sizeof(msg->msg_control));
+			msg->msg_controllen = CMSG_SPACE(sizeof(cookie));
+			msg->msg_control = (struct cmsghdr *)ckbuf;
+			add_zcopy_cookie(msg, ++cookie);
+		}
+	}
 
 	ret = sendmsg(fd, msg, flags);
 	if (ret == -1 && errno == EAGAIN)
@@ -194,6 +216,10 @@ static bool do_sendmsg(int fd, struct msghdr *msg, bool do_zerocopy)
 		if (do_zerocopy && ret)
 			expected_completions++;
 	}
+	if (do_zerocopy && domain == PF_RDS) {
+		msg->msg_control = NULL;
+		msg->msg_controllen = 0;
+	}
 
 	return true;
 }
@@ -220,7 +246,9 @@ static void do_sendmsg_corked(int fd, struct msghdr *msg)
 		msg->msg_iov[0].iov_len = payload_len + extra_len;
 		extra_len = 0;
 
-		do_sendmsg(fd, msg, do_zerocopy);
+		do_sendmsg(fd, msg, do_zerocopy,
+			   (cfg_dst_addr.ss_family == AF_INET ?
+			    PF_INET : PF_INET6));
 	}
 
 	do_setsockopt(fd, IPPROTO_UDP, UDP_CORK, 0);
@@ -316,6 +344,26 @@ static int do_setup_tx(int domain, int type, int protocol)
 	return fd;
 }
 
+static int do_process_zerocopy_cookies(struct sock_extended_err *serr,
+				       uint32_t *ckbuf, size_t nbytes)
+{
+	int ncookies, i;
+
+	if (serr->ee_errno != 0)
+		error(1, 0, "serr: wrong error code: %u", serr->ee_errno);
+	ncookies = serr->ee_data;
+	if (ncookies > SO_EE_ORIGIN_MAX_ZCOOKIES)
+		error(1, 0, "Returned %d cookies, max expected %d\n",
+		      ncookies, SO_EE_ORIGIN_MAX_ZCOOKIES);
+	if (nbytes != ncookies * sizeof(uint32_t))
+		error(1, 0, "Expected %d cookies, got %ld\n",
+		      ncookies, nbytes/sizeof(uint32_t));
+	for (i = 0; i < ncookies; i++)
+		if (cfg_verbose >= 2)
+			fprintf(stderr, "%d\n", ckbuf[i]);
+	return ncookies;
+}
+
 static bool do_recv_completion(int fd)
 {
 	struct sock_extended_err *serr;
@@ -324,10 +372,17 @@ static bool do_recv_completion(int fd)
 	uint32_t hi, lo, range;
 	int ret, zerocopy;
 	char control[100];
+	uint32_t ckbuf[SO_EE_ORIGIN_MAX_ZCOOKIES];
+	struct iovec iov;
 
 	msg.msg_control = control;
 	msg.msg_controllen = sizeof(control);
 
+	iov.iov_base = ckbuf;
+	iov.iov_len = (SO_EE_ORIGIN_MAX_ZCOOKIES * sizeof(ckbuf[0]));
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
 	ret = recvmsg(fd, &msg, MSG_ERRQUEUE);
 	if (ret == -1 && errno == EAGAIN)
 		return false;
@@ -346,6 +401,11 @@ static bool do_recv_completion(int fd)
 		      cm->cmsg_level, cm->cmsg_type);
 
 	serr = (void *) CMSG_DATA(cm);
+
+	if (serr->ee_origin == SO_EE_ORIGIN_ZCOOKIE) {
+		completions += do_process_zerocopy_cookies(serr, ckbuf, ret);
+		return true;
+	}
 	if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY)
 		error(1, 0, "serr: wrong origin: %u", serr->ee_origin);
 	if (serr->ee_errno != 0)
@@ -470,7 +530,7 @@ static void do_tx(int domain, int type, int protocol)
 		if (cfg_cork)
 			do_sendmsg_corked(fd, &msg);
 		else
-			do_sendmsg(fd, &msg, cfg_zerocopy);
+			do_sendmsg(fd, &msg, cfg_zerocopy, domain);
 
 		while (!do_poll(fd, POLLOUT)) {
 			if (cfg_zerocopy)