tcp: add generic netlink support for tcp_metrics

Add support for genl "tcp_metrics". No locking
is changed, only that now we can unlink and delete
entries after grace period. We implement get/del for
single entry and dump to support show/flush filtering
in user space. Del without address attribute causes
flush for all addresses, sadly under genl_mutex.

v2:
- remove rcu_assign_pointer as suggested by Eric Dumazet,
it is not needed because there are no other writes under lock
- move the flushing code in tcp_metrics_flush_all

v3:
- remove synchronize_rcu on flush as suggested by Eric Dumazet

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 55 insertions, 0 deletions

diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index 1f2c1c787f17..90da0af28352 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -363,6 +363,7 @@ header-y += sysctl.h
 header-y += sysinfo.h
 header-y += taskstats.h
 header-y += tcp.h
+header-y += tcp_metrics.h
 header-y += telephony.h
 header-y += termios.h
 header-y += time.h
diff --git a/include/linux/tcp_metrics.h b/include/linux/tcp_metrics.h
new file mode 100644
index 000000000000..cb5157b55f32
--- /dev/null
+++ b/include/linux/tcp_metrics.h
@@ -0,0 +1,54 @@
+/* tcp_metrics.h - TCP Metrics Interface */
+
+#ifndef _LINUX_TCP_METRICS_H
+#define _LINUX_TCP_METRICS_H
+
+#include <linux/types.h>
+
+/* NETLINK_GENERIC related info
+ */
+#define TCP_METRICS_GENL_NAME           "tcp_metrics"
+#define TCP_METRICS_GENL_VERSION        0x1
+
+enum tcp_metric_index {
+        TCP_METRIC_RTT,
+        TCP_METRIC_RTTVAR,
+        TCP_METRIC_SSTHRESH,
+        TCP_METRIC_CWND,
+        TCP_METRIC_REORDERING,
+
+        /* Always last.  */
+        __TCP_METRIC_MAX,
+};
+
+#define TCP_METRIC_MAX  (__TCP_METRIC_MAX - 1)
+
+enum {
+        TCP_METRICS_ATTR_UNSPEC,
+        TCP_METRICS_ATTR_ADDR_IPV4,             /* u32 */
+        TCP_METRICS_ATTR_ADDR_IPV6,             /* binary */
+        TCP_METRICS_ATTR_AGE,                   /* msecs */
+        TCP_METRICS_ATTR_TW_TSVAL,              /* u32, raw, rcv tsval */
+        TCP_METRICS_ATTR_TW_TS_STAMP,           /* s32, sec age */
+        TCP_METRICS_ATTR_VALS,                  /* nested +1, u32 */
+        TCP_METRICS_ATTR_FOPEN_MSS,             /* u16 */
+        TCP_METRICS_ATTR_FOPEN_SYN_DROPS,       /* u16, count of drops */
+        TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,     /* msecs age */
+        TCP_METRICS_ATTR_FOPEN_COOKIE,          /* binary */
+
+        __TCP_METRICS_ATTR_MAX,
+};
+
+#define TCP_METRICS_ATTR_MAX    (__TCP_METRICS_ATTR_MAX - 1)
+
+enum {
+        TCP_METRICS_CMD_UNSPEC,
+        TCP_METRICS_CMD_GET,
+        TCP_METRICS_CMD_DEL,
+
+        __TCP_METRICS_CMD_MAX,
+};
+
+#define TCP_METRICS_CMD_MAX     (__TCP_METRICS_CMD_MAX - 1)
+
+#endif /* _LINUX_TCP_METRICS_H */