On Tue, Sep 15, 2020 at 04:52:59PM -0700, Jakub Kicinski wrote:
> Add support for requesting pause frame stats from the kernel.
>
> # ./ethtool -I -a eth0
> Pause parameters for eth0:
> Autonegotiate: on
> RX: on
> TX: on
> Statistics:
> tx_pause_frames: 1
> rx_pause_frames: 1
>
> # ./ethtool -I --json -a eth0
> [ {
> "ifname": "eth0",
> "autonegotiate": true,
> "rx": true,
> "tx": true,
> "statistics": {
> "tx_pause_frames": 1,
> "rx_pause_frames": 1
> }
> } ]
>
> Signed-off-by: Jakub Kicinski <k...@kernel.org>
> ---
> netlink/pause.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 65 insertions(+), 1 deletion(-)
>
> diff --git a/netlink/pause.c b/netlink/pause.c
> index 30ecdccb15eb..f9dec9fe887a 100644
> --- a/netlink/pause.c
> +++ b/netlink/pause.c
> @@ -5,6 +5,7 @@
> */
>
> #include <errno.h>
> +#include <inttypes.h>
> #include <string.h>
> #include <stdio.h>
>
> @@ -110,6 +111,62 @@ static int show_pause_autoneg_status(struct nl_context
> *nlctx)
> return ret;
> }
>
> +static int show_pause_stats(const struct nlattr *nest)
> +{
> + const struct nlattr *tb[ETHTOOL_A_PAUSE_STAT_MAX + 1] = {};
> + DECLARE_ATTR_TB_INFO(tb);
> + static const struct {
> + unsigned int attr;
> + char *name;
> + } stats[] = {
> + { ETHTOOL_A_PAUSE_STAT_TX_FRAMES, "tx_pause_frames" },
> + { ETHTOOL_A_PAUSE_STAT_RX_FRAMES, "rx_pause_frames" },
> + };
> + bool header = false;
> + unsigned int i;
> + size_t n;
> + int ret;
> +
> + ret = mnl_attr_parse_nested(nest, attr_cb, &tb_info);
> + if (ret < 0)
> + return ret;
> +
> + open_json_object("statistics");
> + for (i = 0; i < ARRAY_SIZE(stats); i++) {
> + char fmt[32];
> +
> + if (!tb[stats[i].attr])
> + continue;
> +
> + if (!header && !is_json_context()) {
> + printf("Statistics:\n");
> + header = true;
> + }
> +
> + if (mnl_attr_validate(tb[stats[i].attr], MNL_TYPE_U64)) {
> + fprintf(stderr, "malformed netlink message
> (statistic)\n");
> + goto err_close_stats;
> + }
> +
> + n = snprintf(fmt, sizeof(fmt), " %s: %%" PRId64 "\n",
> + stats[i].name);
The stats are unsigned so the format should be PRIu64 here.
> + if (n >= sizeof(fmt)) {
> + fprintf(stderr, "internal error - malformed label\n");
> + goto err_close_stats;
> + }
> +
> + print_u64(PRINT_ANY, stats[i].name, fmt,
> + mnl_attr_get_u64(tb[stats[i].attr]));
> + }
> + close_json_object();
> +
> + return 0;
> +
> +err_close_stats:
> + close_json_object();
> + return -1;
> +}
> +
> int pause_reply_cb(const struct nlmsghdr *nlhdr, void *data)
> {
> const struct nlattr *tb[ETHTOOL_A_PAUSE_MAX + 1] = {};
> @@ -147,6 +204,11 @@ int pause_reply_cb(const struct nlmsghdr *nlhdr, void
> *data)
> if (ret < 0)
> goto err_close_dev;
> }
> + if (tb[ETHTOOL_A_PAUSE_STATS]) {
> + ret = show_pause_stats(tb[ETHTOOL_A_PAUSE_STATS]);
> + if (ret < 0)
> + goto err_close_dev;
> + }
> if (!silent)
> print_nl();
>
> @@ -163,6 +225,7 @@ int nl_gpause(struct cmd_context *ctx)
> {
> struct nl_context *nlctx = ctx->nlctx;
> struct nl_socket *nlsk = nlctx->ethnl_socket;
> + u32 flags;
> int ret;
>
> if (netlink_cmd_check(ctx, ETHTOOL_MSG_PAUSE_GET, true))
> @@ -173,8 +236,9 @@ int nl_gpause(struct cmd_context *ctx)
> return 1;
> }
>
> + flags = nlctx->ctx->show_stats ? ETHTOOL_FLAG_STATS : 0;
> ret = nlsock_prep_get_request(nlsk, ETHTOOL_MSG_PAUSE_GET,
> - ETHTOOL_A_PAUSE_HEADER, 0);
> + ETHTOOL_A_PAUSE_HEADER, flags);
> if (ret < 0)
> return ret;
>
When the stats are supported by kernel but not provided by a device,
the request will succeed and usual output without stats will be shown.
However, when stats are requested on a pre-5.10 kernel not recognizing
ETHTOOL_FLAG_STATS, the request will fail:
mike@lion:~/work/git/ethtool> ./ethtool --debug 0x10 -I -a eth0
netlink error: unrecognized request flags
netlink error: Operation not supported
offending message and attribute:
ETHTOOL_MSG_PAUSE_GET
ETHTOOL_A_PAUSE_HEADER
ETHTOOL_A_HEADER_DEV_NAME = "eth0"
===> ETHTOOL_A_HEADER_FLAGS = 0x00000004
We should probably repeat the request with flags=0 in this case but that
would require keeping the offset of ETHTOOL_A_HEADER_FLAGS attribute and
checking for -EOPNOTSUPP with this offset in nlsock_process_ack().
Michal
