Looks fine. A few comments below around code re-use.

On 1/22/21 4:26 AM, Parav Pandit wrote:

The indent code has a lot of parallels with devlink -- including helpers
below around indent_inc and _dec. Please take a look at how to refactor
and re-use.

+
+struct vdpa_socket {
+	struct mnl_socket *nl;
+	char *buf;
+	uint32_t family;
+	unsigned int seq;
+};
+
+static int vdpa_socket_sndrcv(struct vdpa_socket *nlg, const struct nlmsghdr *nlh,
+			      mnl_cb_t data_cb, void *data)
+{
+	int err;
+
+	err = mnl_socket_sendto(nlg->nl, nlh, nlh->nlmsg_len);
+	if (err < 0) {
+		perror("Failed to send data");
+		return -errno;
+	}
+
+	err = mnlu_socket_recv_run(nlg->nl, nlh->nlmsg_seq, nlg->buf, MNL_SOCKET_BUFFER_SIZE,
+				   data_cb, data);
+	if (err < 0) {
+		fprintf(stderr, "vdpa answers: %s\n", strerror(errno));
+		return -errno;
+	}
+	return 0;
+}
+
+static int get_family_id_attr_cb(const struct nlattr *attr, void *data)
+{
+	int type = mnl_attr_get_type(attr);
+	const struct nlattr **tb = data;
+
+	if (mnl_attr_type_valid(attr, CTRL_ATTR_MAX) < 0)
+		return MNL_CB_ERROR;
+
+	if (type == CTRL_ATTR_FAMILY_ID &&
+	    mnl_attr_validate(attr, MNL_TYPE_U16) < 0)
+		return MNL_CB_ERROR;
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static int get_family_id_cb(const struct nlmsghdr *nlh, void *data)
+{
+	struct genlmsghdr *genl = mnl_nlmsg_get_payload(nlh);
+	struct nlattr *tb[CTRL_ATTR_MAX + 1] = {};
+	uint32_t *p_id = data;
+
+	mnl_attr_parse(nlh, sizeof(*genl), get_family_id_attr_cb, tb);
+	if (!tb[CTRL_ATTR_FAMILY_ID])
+		return MNL_CB_ERROR;
+	*p_id = mnl_attr_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
+	return MNL_CB_OK;
+}
+
+static int family_get(struct vdpa_socket *nlg)
+{
+	struct genlmsghdr hdr = {};
+	struct nlmsghdr *nlh;
+	int err;
+
+	hdr.cmd = CTRL_CMD_GETFAMILY;
+	hdr.version = 0x1;
+
+	nlh = mnlu_msg_prepare(nlg->buf, GENL_ID_CTRL,
+			       NLM_F_REQUEST | NLM_F_ACK,
+			       &hdr, sizeof(hdr));
+
+	mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME, VDPA_GENL_NAME);
+
+	err = mnl_socket_sendto(nlg->nl, nlh, nlh->nlmsg_len);
+	if (err < 0)
+		return err;
+
+	err = mnlu_socket_recv_run(nlg->nl, nlh->nlmsg_seq, nlg->buf,
+				   MNL_SOCKET_BUFFER_SIZE,
+				   get_family_id_cb, &nlg->family);
+	return err;
+}
+
+static int vdpa_socket_open(struct vdpa_socket *nlg)
+{
+	int err;
+
+	nlg->buf = malloc(MNL_SOCKET_BUFFER_SIZE);
+	if (!nlg->buf)
+		goto err_buf_alloc;
+
+	nlg->nl = mnlu_socket_open(NETLINK_GENERIC);
+	if (!nlg->nl)
+		goto err_socket_open;
+
+	err = family_get(nlg);
+	if (err)
+		goto err_socket;
+
+	return 0;
+
+err_socket:
+	mnl_socket_close(nlg->nl);
+err_socket_open:
+	free(nlg->buf);
+err_buf_alloc:
+	return -1;
+}

The above 4 functions duplicate a lot of devlink functionality. Please
create a helper in lib/mnl_utils.c that can be used in both.

+
+static void vdpa_socket_close(struct vdpa_socket *nlg)
+{
+	mnl_socket_close(nlg->nl);
+	free(nlg->buf);
+}
+
+#define VDPA_OPT_MGMTDEV_HANDLE		BIT(0)
+#define VDPA_OPT_VDEV_MGMTDEV_HANDLE	BIT(1)
+#define VDPA_OPT_VDEV_NAME 		BIT(2)
+#define VDPA_OPT_VDEV_HANDLE 		BIT(3)
+
+struct vdpa_opts {
+	uint64_t present; /* flags of present items */
+	const char *mdev_bus_name;
+	const char *mdev_name;
+	const char *vdev_name;
+	unsigned int device_id;
+};
+
+struct vdpa {
+	struct vdpa_socket nlg;
+	struct vdpa_opts opts;
+	bool json_output;
+};
+
+static void indent_inc(void)
+{
+	if (g_indent_level + INDENT_STR_STEP > INDENT_STR_MAXLEN)
+		return;
+	g_indent_level += INDENT_STR_STEP;
+	memset(g_indent_str, ' ', sizeof(g_indent_str));
+	g_indent_str[g_indent_level] = '\0';
+}
+
+static void indent_dec(void)
+{
+	if (g_indent_level - INDENT_STR_STEP < 0)
+		return;
+	g_indent_level -= INDENT_STR_STEP;
+	g_indent_str[g_indent_level] = '\0';
+}
+
+static void indent_print(void)
+{
+	if (g_indent_level)
+		printf("%s", g_indent_str);
+}
+
+static void pr_out_section_start(struct vdpa *vdpa, const char *name)
+{
+	open_json_object(NULL);
+	open_json_object(name);
+}
+
+static void pr_out_section_end(struct vdpa *vdpa)
+{
+	close_json_object();
+	close_json_object();
+}
+
+static void pr_out_array_start(struct vdpa *vdpa, const char *name)
+{
+	if (!vdpa->json_output) {
+		print_nl();
+		indent_inc();
+		indent_print();
+	}
+	open_json_array(PRINT_ANY, name);
+}
+
+static void pr_out_array_end(struct vdpa *vdpa)
+{
+	close_json_array(PRINT_JSON, NULL);
+	if (!vdpa->json_output)
+		indent_dec();
+}
+
+static const enum mnl_attr_data_type vdpa_policy[VDPA_ATTR_MAX + 1] = {
+	[VDPA_ATTR_MGMTDEV_BUS_NAME] = MNL_TYPE_NUL_STRING,
+	[VDPA_ATTR_MGMTDEV_DEV_NAME] = MNL_TYPE_NUL_STRING,
+	[VDPA_ATTR_DEV_NAME] = MNL_TYPE_STRING,
+	[VDPA_ATTR_DEV_ID] = MNL_TYPE_U32,
+	[VDPA_ATTR_DEV_VENDOR_ID] = MNL_TYPE_U32,
+	[VDPA_ATTR_DEV_MAX_VQS] = MNL_TYPE_U32,
+	[VDPA_ATTR_DEV_MAX_VQ_SIZE] = MNL_TYPE_U16,
+};
+
+static int attr_cb(const struct nlattr *attr, void *data)
+{
+	const struct nlattr **tb = data;
+	int type;
+
+	if (mnl_attr_type_valid(attr, VDPA_ATTR_MAX) < 0)
+		return MNL_CB_OK;
+
+	type = mnl_attr_get_type(attr);
+	if (mnl_attr_validate(attr, vdpa_policy[type]) < 0)
+		return MNL_CB_ERROR;
+
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static unsigned int strslashcount(char *str)
+{
+	unsigned int count = 0;
+	char *pos = str;
+
+	while ((pos = strchr(pos, '/'))) {
+		count++;
+		pos++;
+	}
+	return count;
+}

you could make that a generic function (e.g., str_char_count) by passing
'/' as an input.

+
+static int strslashrsplit(char *str, const char **before, const char **after)
+{
+	char *slash;
+
+	slash = strrchr(str, '/');
+	if (!slash)
+		return -EINVAL;
+	*slash = '\0';
+	*before = str;
+	*after = slash + 1;
+	return 0;
+}

similarly here. If you start with things like this in lib/utils you make
it easier for follow on users to find.


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