From: peltan <peltan@localhost.localdomain>
Date: Mon, 6 Jan 2020 17:28:01 +0000 (+0100)
Subject: xdp: load bpf program exactly once at knotd start
X-Git-Tag: embedded_lmdb~35^2~74
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=66cbd962b6803f3f6ec2dcdc3d5b87d09653ab29;p=thirdparty%2Fknot-dns.git

xdp: load bpf program exactly once at knotd start
---

diff --git a/src/knot/server/server.c b/src/knot/server/server.c
index 847dac4a2a..a121508d17 100644
--- a/src/knot/server/server.c
+++ b/src/knot/server/server.c
@@ -361,7 +361,7 @@ static iface_t *server_init_iface(struct sockaddr_storage *addr,
 		}
 
 		ret = knot_xsk_init(new_if->sock_xdp + i, dev, i,
-		                    sockaddr_port(addr));
+		                    sockaddr_port(addr), i == 0);
 		free(dev);
 		if (ret != KNOT_EOK) {
 			log_warning("failed to init XDP (%s)", knot_strerror(ret));
diff --git a/src/libknot/xdp/af_xdp.c b/src/libknot/xdp/af_xdp.c
index d6d25f12f5..437349c30e 100644
--- a/src/libknot/xdp/af_xdp.c
+++ b/src/libknot/xdp/af_xdp.c
@@ -163,7 +163,7 @@ void knot_xsk_deinit(struct knot_xsk_socket *socket)
 	xsk_socket__delete(socket->xsk);
 	xsk_umem__delete(socket->umem->umem);
 
-	kxsk_iface_free((struct kxsk_iface *)/*const-cast*/socket->iface, true);
+	kxsk_iface_free((struct kxsk_iface *)/*const-cast*/socket->iface);
 	free(socket);
 }
 
@@ -599,13 +599,13 @@ void knot_xsk_free_recvd(struct knot_xsk_socket *socket, const knot_xsk_msg_t *m
 
 _public_
 int knot_xsk_init(struct knot_xsk_socket **socket, const char *ifname, int if_queue,
-                  int listen_port)
+                  int listen_port, bool load_bpf)
 {
 	if (socket == NULL || *socket != NULL) {
 		return KNOT_EINVAL;
 	}
 
-	struct kxsk_iface *iface = kxsk_iface_new(ifname);
+	struct kxsk_iface *iface = kxsk_iface_new(ifname, load_bpf);
 	if (!iface) {
 		return KNOT_EINVAL;
 	}
@@ -614,14 +614,14 @@ int knot_xsk_init(struct knot_xsk_socket **socket, const char *ifname, int if_qu
 	struct xsk_umem_info *umem =
 		configure_xsk_umem(&global_umem_config, UMEM_FRAME_COUNT);
 	if (umem == NULL) {
-		kxsk_iface_free(iface, false);
+		kxsk_iface_free(iface);
 		return KNOT_ENOMEM;
 	}
 
 	*socket = xsk_configure_socket(umem, iface, if_queue);
 	if (!*socket) {
 		xsk_umem__delete(umem->umem);
-		kxsk_iface_free(iface, false);
+		kxsk_iface_free(iface);
 		return KNOT_NET_ESOCKET;
 	}
 
@@ -629,7 +629,7 @@ int knot_xsk_init(struct knot_xsk_socket **socket, const char *ifname, int if_qu
 	if (ret != KNOT_EOK) {
 		xsk_socket__delete((*socket)->xsk);
 		xsk_umem__delete((*socket)->umem->umem);
-		kxsk_iface_free(iface, false);
+		kxsk_iface_free(iface);
 		free(*socket);
 		*socket = NULL;
 		return ret;
diff --git a/src/libknot/xdp/af_xdp.h b/src/libknot/xdp/af_xdp.h
index 6a21380c48..c3b2fa171d 100644
--- a/src/libknot/xdp/af_xdp.h
+++ b/src/libknot/xdp/af_xdp.h
@@ -32,7 +32,7 @@ typedef struct {
 struct knot_xsk_socket;
 
 int knot_xsk_init(struct knot_xsk_socket **socket, const char *ifname, int if_queue,
-                  int listen_port);
+                  int listen_port, bool load_bpf);
 
 void knot_xsk_deinit(struct knot_xsk_socket *socket);
 
diff --git a/src/libknot/xdp/bpf-user.c b/src/libknot/xdp/bpf-user.c
index 520b1bd09a..902acc63a1 100644
--- a/src/libknot/xdp/bpf-user.c
+++ b/src/libknot/xdp/bpf-user.c
@@ -30,19 +30,10 @@
 
 static int ensure_udp_prog(struct kxsk_iface *iface, const char *prog_fname)
 {
-	int ret;
-
-	uint32_t prog_id;
-	ret = bpf_get_link_xdp_id(iface->ifindex, &prog_id, 0);
-	if (ret)
-		return -abs(ret);
-	if (prog_id)
-		return bpf_prog_get_fd_by_id(prog_id);
-
 	/* Use libbpf for extracting BPF byte-code from BPF-ELF object, and
 	 * loading this into the kernel via bpf-syscall */
 	int prog_fd;
-	ret = bpf_prog_load(prog_fname, BPF_PROG_TYPE_XDP, &iface->prog_obj, &prog_fd);
+	int ret = bpf_prog_load(prog_fname, BPF_PROG_TYPE_XDP, &iface->prog_obj, &prog_fd);
 	if (ret) {
 		fprintf(stderr, "[kxsk] failed loading BPF program (%s) (%d): %s\n",
 			prog_fname, ret, strerror(-ret));
@@ -54,7 +45,7 @@ static int ensure_udp_prog(struct kxsk_iface *iface, const char *prog_fname)
 		fprintf(stderr, "bpf_set_link_xdp_fd() == %d\n", ret);
 		return -abs(ret);
 	} else {
-		fprintf(stderr, "[kxsk] loaded BPF program\n");
+		fprintf(stderr, "[kxsk] loaded BPF program %d %d\n", iface->ifindex, prog_fd);
 	}
 
 	return prog_fd;
@@ -199,9 +190,9 @@ int kxsk_socket_stop(const struct kxsk_iface *iface, int queue_id)
 	return err;
 }
 
-struct kxsk_iface * kxsk_iface_new(const char *ifname)
+struct kxsk_iface * kxsk_iface_new(const char *ifname, bool load_bpf)
 {
-	struct kxsk_iface *iface = malloc(sizeof(*iface));
+	struct kxsk_iface *iface = calloc(1, sizeof(*iface));
 	if (!iface) {
 		errno = ENOMEM;
 		return NULL;
@@ -214,7 +205,17 @@ struct kxsk_iface * kxsk_iface_new(const char *ifname)
 	}
 	iface->qidconf_map_fd = iface->xsks_map_fd = -1;
 
-	int ret = ensure_udp_prog_builtin(iface);
+	int ret;
+	if (load_bpf) {
+		ret = ensure_udp_prog_builtin(iface);
+	} else {
+		uint32_t prog_id = 0;
+		ret = bpf_get_link_xdp_id(iface->ifindex, &prog_id, 0);
+		if (!ret && prog_id) {
+			ret = bpf_prog_get_fd_by_id(prog_id);
+		}
+	}
+
 	if (ret >= 0)
 		ret = get_bpf_maps(ret, iface);
 
@@ -227,15 +228,14 @@ struct kxsk_iface * kxsk_iface_new(const char *ifname)
 	iface->ifname = strdup(iface->ifname);
 	return iface;
 }
-void kxsk_iface_free(struct kxsk_iface *iface, bool unload_bpf)
+void kxsk_iface_free(struct kxsk_iface *iface)
 {
 	unget_bpf_maps(iface);
 
-	if (unload_bpf) {
-		int ret = bpf_set_link_xdp_fd(iface->ifindex, -1, 0);
-		printf("set link fd %d (%s) %d\n", ret, strerror(errno), iface->ifindex);
+	if (iface->prog_obj != NULL) {
 		(void)bpf_object__close(iface->prog_obj);
 	}
+
 	free((char *)/*const-cast*/iface->ifname);
 	free(iface);
 }
diff --git a/src/libknot/xdp/bpf-user.h b/src/libknot/xdp/bpf-user.h
index da12f70236..5293462e9f 100644
--- a/src/libknot/xdp/bpf-user.h
+++ b/src/libknot/xdp/bpf-user.h
@@ -96,14 +96,14 @@ typedef struct knot_xsk_socket {
  * Note: if one is loaded on the interface already, we assume it's ours.
  * LATER: it might be possible to check, e.g. by naming our maps unusually.
  */
-struct kxsk_iface * kxsk_iface_new(const char *ifname);
+struct kxsk_iface * kxsk_iface_new(const char *ifname, bool load_bpf);
 
 /** Undo kxsk_iface_new().  It's always freed, even if some problems happen.
  *
  * Unloading the BPF program is optional, as keeping it only adds some overhead,
  * and in case of multi-process it isn't easy to find that we're the last instance.
  */
-void kxsk_iface_free(struct kxsk_iface *iface, bool unload_bpf);
+void kxsk_iface_free(struct kxsk_iface *iface);
 
 /** Activate this AF_XDP socket through the BPF maps. */
 int kxsk_socket_start(const struct kxsk_iface *iface, int queue_id,