samples, bpf: Move routes monitor in xdp_router_ipv4 in a dedicated thread

In order to not miss any netlink message from the kernel, move routes
monitor to a dedicated thread.

Fixes: 85bf1f51691c ("samples: bpf: Convert xdp_router_ipv4 to XDP samples helper")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/e364b817c69ded73be24b677ab47a157f7c21b64.1649167911.git.lorenzo@kernel.org

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 342a41a..8fff5ad 100644 (file)
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -219,7 +219,7 @@ TPROGLDLIBS_xdp_redirect    += -lm
 TPROGLDLIBS_xdp_redirect_cpu   += -lm
 TPROGLDLIBS_xdp_redirect_map   += -lm
 TPROGLDLIBS_xdp_redirect_map_multi += -lm
-TPROGLDLIBS_xdp_router_ipv4    += -lm
+TPROGLDLIBS_xdp_router_ipv4    += -lm -pthread
 TPROGLDLIBS_tracex4            += -lrt
 TPROGLDLIBS_trace_output       += -lrt
 TPROGLDLIBS_map_perf_test      += -lrt

diff --git a/samples/bpf/xdp_router_ipv4_user.c b/samples/bpf/xdp_router_ipv4_user.c
index 7828784..f32bbd5 100644 (file)
--- a/samples/bpf/xdp_router_ipv4_user.c
+++ b/samples/bpf/xdp_router_ipv4_user.c
@@ -25,6 +25,7 @@
 #include <sys/resource.h>
 #include <libgen.h>
 #include <getopt.h>
+#include <pthread.h>
 #include "xdp_sample_user.h"
 #include "xdp_router_ipv4.skel.h"
 
@@ -38,6 +39,9 @@ static int arp_table_map_fd;
 static int exact_match_map_fd;
 static int tx_port_map_fd;
 
+static bool routes_thread_exit;
+static int interval = 5;
+
 static int mask = SAMPLE_RX_CNT | SAMPLE_REDIRECT_ERR_MAP_CNT |
                  SAMPLE_DEVMAP_XMIT_CNT_MULTI | SAMPLE_EXCEPTION_CNT;
 
@@ -445,7 +449,7 @@ cleanup:
 /* Function to keep track and update changes in route and arp table
  * Give regular statistics of packets forwarded
  */
-static void monitor_route(void *ctx)
+static void *monitor_routes_thread(void *arg)
 {
        struct pollfd fds_route, fds_arp;
        struct sockaddr_nl la, lr;
@@ -455,7 +459,7 @@ static void monitor_route(void *ctx)
        sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
        if (sock < 0) {
                fprintf(stderr, "open netlink socket: %s\n", strerror(errno));
-               return;
+               return NULL;
        }
 
        fcntl(sock, F_SETFL, O_NONBLOCK);
@@ -465,7 +469,7 @@ static void monitor_route(void *ctx)
        if (bind(sock, (struct sockaddr *)&lr, sizeof(lr)) < 0) {
                fprintf(stderr, "bind netlink socket: %s\n", strerror(errno));
                close(sock);
-               return;
+               return NULL;
        }
 
        fds_route.fd = sock;
@@ -475,7 +479,7 @@ static void monitor_route(void *ctx)
        if (sock_arp < 0) {
                fprintf(stderr, "open netlink socket: %s\n", strerror(errno));
                close(sock);
-               return;
+               return NULL;
        }
 
        fcntl(sock_arp, F_SETFL, O_NONBLOCK);
@@ -490,35 +494,51 @@ static void monitor_route(void *ctx)
        fds_arp.fd = sock_arp;
        fds_arp.events = POLL_IN;
 
-       memset(buf, 0, sizeof(buf));
-       if (poll(&fds_route, 1, 3) == POLL_IN) {
-               nll = recv_msg(lr, sock);
-               if (nll < 0) {
-                       fprintf(stderr, "recv from netlink: %s\n",
-                               strerror(nll));
-                       goto cleanup;
-               }
+       /* dump route and arp tables */
+       if (get_arp_table(AF_INET) < 0) {
+               fprintf(stderr, "Failed reading arp table\n");
+               goto cleanup;
+       }
 
-               nh = (struct nlmsghdr *)buf;
-               read_route(nh, nll);
+       if (get_route_table(AF_INET) < 0) {
+               fprintf(stderr, "Failed reading route table\n");
+               goto cleanup;
        }
 
-       memset(buf, 0, sizeof(buf));
-       if (poll(&fds_arp, 1, 3) == POLL_IN) {
-               nll = recv_msg(la, sock_arp);
-               if (nll < 0) {
-                       fprintf(stderr, "recv from netlink: %s\n",
-                               strerror(nll));
-                       goto cleanup;
+       while (!routes_thread_exit) {
+               memset(buf, 0, sizeof(buf));
+               if (poll(&fds_route, 1, 3) == POLL_IN) {
+                       nll = recv_msg(lr, sock);
+                       if (nll < 0) {
+                               fprintf(stderr, "recv from netlink: %s\n",
+                                       strerror(nll));
+                               goto cleanup;
+                       }
+
+                       nh = (struct nlmsghdr *)buf;
+                       read_route(nh, nll);
                }
 
-               nh = (struct nlmsghdr *)buf;
-               read_arp(nh, nll);
+               memset(buf, 0, sizeof(buf));
+               if (poll(&fds_arp, 1, 3) == POLL_IN) {
+                       nll = recv_msg(la, sock_arp);
+                       if (nll < 0) {
+                               fprintf(stderr, "recv from netlink: %s\n",
+                                       strerror(nll));
+                               goto cleanup;
+                       }
+
+                       nh = (struct nlmsghdr *)buf;
+                       read_arp(nh, nll);
+               }
+
+               sleep(interval);
        }
 
 cleanup:
        close(sock_arp);
        close(sock);
+       return NULL;
 }
 
 static void usage(char *argv[], const struct option *long_options,
@@ -531,10 +551,11 @@ static void usage(char *argv[], const struct option *long_options,
 int main(int argc, char **argv)
 {
        bool error = true, generic = false, force = false;
-       int opt, interval = 5, ret = EXIT_FAIL_BPF;
+       int opt, ret = EXIT_FAIL_BPF;
        struct xdp_router_ipv4 *skel;
        int i, total_ifindex = argc - 1;
        char **ifname_list = argv + 1;
+       pthread_t routes_thread;
        int longindex = 0;
 
        if (libbpf_set_strict_mode(LIBBPF_STRICT_ALL) < 0) {
@@ -653,24 +674,25 @@ int main(int argc, char **argv)
                        goto end_destroy;
        }
 
-       if (get_route_table(AF_INET) < 0) {
-               fprintf(stderr, "Failed reading routing table\n");
+       ret = pthread_create(&routes_thread, NULL, monitor_routes_thread, NULL);
+       if (ret) {
+               fprintf(stderr, "Failed creating routes_thread: %s\n", strerror(-ret));
+               ret = EXIT_FAIL;
                goto end_destroy;
        }
 
-       if (get_arp_table(AF_INET) < 0) {
-               fprintf(stderr, "Failed reading arptable\n");
-               goto end_destroy;
-       }
+       ret = sample_run(interval, NULL, NULL);
+       routes_thread_exit = true;
 
-       ret = sample_run(interval, monitor_route, NULL);
        if (ret < 0) {
                fprintf(stderr, "Failed during sample run: %s\n", strerror(-ret));
                ret = EXIT_FAIL;
-               goto end_destroy;
+               goto end_thread_wait;
        }
        ret = EXIT_OK;
 
+end_thread_wait:
+       pthread_join(routes_thread, NULL);
 end_destroy:
        xdp_router_ipv4__destroy(skel);
 end: