Re: [tipc-discussion] [iproute2-next v2] tipc: add support for the netlink extack

[Jon M. <jm...@re...>]

On 3/23/21 5:06 AM, Hoang Le wrote:
> Add support extack in tipc to dump the netlink extack error messages
> (i.e -EINVAL) sent from kernel.
>
> Signed-off-by: Hoang Le <hoa...@de...>
> ---
>   tipc/msg.c | 29 ++++++++++++++++++++++-------
>   1 file changed, 22 insertions(+), 7 deletions(-)
>
> diff --git a/tipc/msg.c b/tipc/msg.c
> index dc09d05048f3..f29b2f8d35ad 100644
> --- a/tipc/msg.c
> +++ b/tipc/msg.c
> @@ -18,6 +18,7 @@
>   #include <linux/genetlink.h>
>   #include <libmnl/libmnl.h>
>   
> +#include "libnetlink.h"
>   #include "msg.h"
>   
>   int parse_attrs(const struct nlattr *attr, void *data)
> @@ -49,6 +50,7 @@ static struct mnl_socket *msg_send(struct nlmsghdr *nlh)
>   {
>   	int ret;
>   	struct mnl_socket *nl;
> +	int one = 1;
>   
>   	nl = mnl_socket_open(NETLINK_GENERIC);
>   	if (nl == NULL) {
> @@ -56,6 +58,8 @@ static struct mnl_socket *msg_send(struct nlmsghdr *nlh)
>   		return NULL;
>   	}
>   
> +	/* support to get extended ACK */
> +	mnl_socket_setsockopt(nl, NETLINK_EXT_ACK, &one, sizeof(one));
>   	ret = mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID);
>   	if (ret < 0) {
>   		perror("mnl_socket_bind");
> @@ -73,21 +77,32 @@ static struct mnl_socket *msg_send(struct nlmsghdr *nlh)
>   
>   static int msg_recv(struct mnl_socket *nl, mnl_cb_t callback, void *data, int seq)
>   {
> -	int ret;
>   	unsigned int portid;
>   	char buf[MNL_SOCKET_BUFFER_SIZE];
> +	struct nlmsghdr *h;
> +	size_t num_bytes;
> +	int is_err = 0;
> +	int ret = 0;
>   
>   	portid = mnl_socket_get_portid(nl);
>   
> -	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
> -	while (ret > 0) {
> -		ret = mnl_cb_run(buf, ret, seq, portid, callback, data);
> +	num_bytes = mnl_socket_recvfrom(nl, buf, sizeof(buf));
> +	while (num_bytes > 0) {
> +		ret = mnl_cb_run(buf, num_bytes, seq, portid, callback, data);
>   		if (ret <= 0)
>   			break;
> -		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
> +		num_bytes = mnl_socket_recvfrom(nl, buf, sizeof(buf));
> +	}
> +
> +	if (ret == -1) {
> +		if (num_bytes > 0) {
> +			h = (struct nlmsghdr *)buf;
> +			is_err = nl_dump_ext_ack(h, NULL);
> +		}
> +
> +		if (!is_err)
> +			perror("error");
>   	}
> -	if (ret == -1)
> -		perror("error");
>   
>   	mnl_socket_close(nl);
>   
Acked-by: Jon Maloy <jm...@re...>

Thanks, Hoang.