[PATCH ethtool-next 5/5] pause: add support for dumping statistics

[Jakub Kicinski]

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);
+               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;
 
-- 
2.26.2