tcp: prepare CC get_info() access from getsockopt()

We would like that optional info provided by Congestion Control
modules using netlink can also be read using getsockopt()

This patch changes get_info() to put this information in a buffer,
instead of skb, like tcp_get_info(), so that following patch
can reuse this common infrastructure.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 8 insertions, 1 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index dd7b4ea6a10c..6d204f3f9df8 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -804,6 +804,8 @@ enum tcp_ca_ack_event_flags {
 /* Requires ECN/ECT set on all packets */
 #define TCP_CONG_NEEDS_ECN      0x2
 
+union tcp_cc_info;
+
 struct tcp_congestion_ops {
         struct list_head        list;
         u32 key;
@@ -829,7 +831,8 @@ struct tcp_congestion_ops {
         /* hook for packet ack accounting (optional) */
         void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
         /* get info for inet_diag (optional) */
-        int (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
+        size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
+                           union tcp_cc_info *info);
 
         char            name[TCP_CA_NAME_MAX];
         struct module   *owner;
diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
index d65c0a09efd3..c7093c75bdd6 100644
--- a/include/uapi/linux/inet_diag.h
+++ b/include/uapi/linux/inet_diag.h
@@ -143,4 +143,8 @@ struct tcp_dctcp_info {
         __u32   dctcp_ab_tot;
 };
 
+union tcp_cc_info {
+        struct tcpvegas_info    vegas;
+        struct tcp_dctcp_info   dctcp;
+};
 #endif /* _UAPI_INET_DIAG_H_ */