Move open_bpf_map_file to common/

Move the open_bpf_map_file function to the common/ directory and move code to
get map info to this function from the check_map_fd_info function.  This patch
is needed to make the implementation of basic04 solutions shorter.

Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>

Author: aspsk

basic04-pinning-maps/xdp_stats.c

@@ -214,30 +214,6 @@ static void stats_poll(int map_fd, __u32 map_type, int interval)
 #define PATH_MAX	4096
 #endif
 
-int open_bpf_map_file(const char *pin_dir, const char *mapname)
-{
-	char filename[PATH_MAX];
-	int len, fd;
-
-	len = snprintf(filename, PATH_MAX, "%s/%s", pin_dir, mapname);
-	if (len < 0) {
-		fprintf(stderr, "ERR: constructing full mapname path\n");
-		return -1;
-	}
-
-	/* Lesson#1: There is only a weak dependency to libbpf here as
-	 * bpf_obj_get is a simple wrapper around the bpf-syscall
-	 */
-	fd = bpf_obj_get(filename);
-	if (fd < 0) {
-		fprintf(stderr,
-			"WARN: Failed to open bpf map file:%s err(%d):%s\n",
-			filename, errno, strerror(errno));
-		return fd;
-	}
-	return fd;
-}
-
 const char *pin_basedir =  "/sys/fs/bpf";
 
 int main(int argc, char **argv)
@@ -271,7 +247,7 @@ int main(int argc, char **argv)
 		return EXIT_FAIL_OPTION;
 	}
 
-	stats_map_fd = open_bpf_map_file(pin_dir, "xdp_stats_map");
+	stats_map_fd = open_bpf_map_file(pin_dir, "xdp_stats_map", &info);
 	if (stats_map_fd < 0) {
 		return EXIT_FAIL_BPF;
 	}
@@ -280,7 +256,7 @@ int main(int argc, char **argv)
 	map_expect.key_size    = sizeof(__u32);
 	map_expect.value_size  = sizeof(struct datarec);
 	map_expect.max_entries = XDP_ACTION_MAX;
-	err = check_map_fd_info(stats_map_fd, &info, &map_expect);
+	err = check_map_fd_info(&info, &map_expect);
 	if (err) {
 		fprintf(stderr, "ERR: map via FD not compatible\n");
 		return err;

common/common_user_bpf_xdp.c

@@ -200,23 +200,9 @@ const char *action2str(__u32 action)
         return NULL;
 }
 
-int check_map_fd_info(int map_fd, struct bpf_map_info *info,
-		      struct bpf_map_info *exp)
+int check_map_fd_info(const struct bpf_map_info *info,
+		      const struct bpf_map_info *exp)
 {
-	__u32 info_len = sizeof(*info);
-	int err;
-
-	if (map_fd < 0)
-		return EXIT_FAIL;
-
-        /* BPF-info via bpf-syscall */
-	err = bpf_obj_get_info_by_fd(map_fd, info, &info_len);
-	if (err) {
-		fprintf(stderr, "ERR: %s() can't get info - %s\n",
-			__func__,  strerror(errno));
-		return EXIT_FAIL_BPF;
-	}
-
 	if (exp->key_size && exp->key_size != info->key_size) {
 		fprintf(stderr, "ERR: %s() "
 			"Map key size(%d) mismatch expected size(%d)\n",
@@ -244,3 +230,40 @@ int check_map_fd_info(int map_fd, struct bpf_map_info *info,
 
 	return 0;
 }
+
+int open_bpf_map_file(const char *pin_dir,
+		      const char *mapname,
+		      struct bpf_map_info *info)
+{
+	char filename[PATH_MAX];
+	int err, len, fd;
+	__u32 info_len = sizeof(*info);
+
+	len = snprintf(filename, PATH_MAX, "%s/%s", pin_dir, mapname);
+	if (len < 0) {
+		fprintf(stderr, "ERR: constructing full mapname path\n");
+		return -1;
+	}
+
+	/* Lesson#1: There is only a weak dependency to libbpf here as
+	 * bpf_obj_get is a simple wrapper around the bpf-syscall
+	 */
+	fd = bpf_obj_get(filename);
+	if (fd < 0) {
+		fprintf(stderr,
+			"WARN: Failed to open bpf map file:%s err(%d):%s\n",
+			filename, errno, strerror(errno));
+		return fd;
+	}
+
+	if (info) {
+		err = bpf_obj_get_info_by_fd(fd, info, &info_len);
+		if (err) {
+			fprintf(stderr, "ERR: %s() can't get info - %s\n",
+				__func__,  strerror(errno));
+			return EXIT_FAIL_BPF;
+		}
+	}
+
+	return fd;
+}

common/common_user_bpf_xdp.h

@@ -10,7 +10,11 @@ struct bpf_object *load_bpf_and_xdp_attach(struct config *cfg);
 
 const char *action2str(__u32 action);
 
-int check_map_fd_info(int map_fd, struct bpf_map_info *info,
-                      struct bpf_map_info *exp);
+int check_map_fd_info(const struct bpf_map_info *info,
+                      const struct bpf_map_info *exp);
+
+int open_bpf_map_file(const char *pin_dir,
+		      const char *mapname,
+		      struct bpf_map_info *info);
 
 #endif /* __COMMON_USER_BPF_XDP_H */

packet-solutions/xdp_prog_user.c

@@ -103,27 +103,6 @@ static int write_iface_params(int map_fd, unsigned char *src, unsigned char *des
 #define PATH_MAX 4096
 #endif
 
-int open_bpf_map_file(const char *pin_dir, const char *mapname)
-{
-	char filename[PATH_MAX];
-	int len, fd;
-
-	len = snprintf(filename, PATH_MAX, "%s/%s", pin_dir, mapname);
-	if (len < 0) {
-		fprintf(stderr, "ERR: constructing full mapname path\n");
-		return -1;
-	}
-
-	fd = bpf_obj_get(filename);
-	if (fd < 0) {
-		fprintf(stderr,
-			"WARN: Failed to open bpf map file:%s err(%d):%s\n",
-			filename, errno, strerror(errno));
-		return fd;
-	}
-	return fd;
-}
-
 const char *pin_basedir =  "/sys/fs/bpf";
 
 int main(int argc, char **argv)
@@ -169,7 +148,7 @@ int main(int argc, char **argv)
 	}
 
 	/* Open the tx_port map corresponding to the cfg.ifname interface */
-	map_fd = open_bpf_map_file(pin_dir, "tx_port");
+	map_fd = open_bpf_map_file(pin_dir, "tx_port", NULL);
 	if (map_fd < 0) {
 		return EXIT_FAIL_BPF;
 	}
@@ -183,7 +162,7 @@ int main(int argc, char **argv)
 		printf("redirect from ifnum=%d to ifnum=%d\n", cfg.ifindex, cfg.redirect_ifindex);
 
 		/* Open the redirect_params map */
-		map_fd = open_bpf_map_file(pin_dir, "redirect_params");
+		map_fd = open_bpf_map_file(pin_dir, "redirect_params", NULL);
 		if (map_fd < 0) {
 			return EXIT_FAIL_BPF;
 		}