[TCP]: Export accept queue len of a TCP listening socket via rx_queue

While debugging a TCP server hang issue, we noticed that currently there is
no way for a user to get the acceptq backlog value for a TCP listen socket.

All the standard networking utilities that display socket info like netstat,
ss and /proc/net/tcp have 2 fields called rx_queue and tx_queue. These
fields do not mean much for listening sockets. This patch uses one of these
unused fields(rx_queue) to export the accept queue len for listening sockets.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index c148c10..b56399c 100644 (file)
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -26,7 +26,10 @@ static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
        const struct tcp_sock *tp = tcp_sk(sk);
        struct tcp_info *info = _info;
 
-       r->idiag_rqueue = tp->rcv_nxt - tp->copied_seq;
+       if (sk->sk_state == TCP_LISTEN)
+               r->idiag_rqueue = sk->sk_ack_backlog;
+       else
+               r->idiag_rqueue = tp->rcv_nxt - tp->copied_seq;
        r->idiag_wqueue = tp->write_seq - tp->snd_una;
        if (info != NULL)
                tcp_get_info(sk, info);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 25ecc6e..4c6ef47 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1726,7 +1726,8 @@ static void get_tcp4_sock(struct sock *sp, char *tmpbuf, int i)
        sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
                        "%08X %5d %8d %lu %d %p %u %u %u %u %d",
                i, src, srcp, dest, destp, sp->sk_state,
-               tp->write_seq - tp->snd_una, tp->rcv_nxt - tp->copied_seq,
+               tp->write_seq - tp->snd_una,
+               (sp->sk_state == TCP_LISTEN) ? sp->sk_ack_backlog : (tp->rcv_nxt - tp->copied_seq),
                timer_active,
                jiffies_to_clock_t(timer_expires - jiffies),
                icsk->icsk_retransmits,

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index a50eb30..b36d5b2 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1469,7 +1469,8 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
                   dest->s6_addr32[0], dest->s6_addr32[1],
                   dest->s6_addr32[2], dest->s6_addr32[3], destp,
                   sp->sk_state, 
-                  tp->write_seq-tp->snd_una, tp->rcv_nxt-tp->copied_seq,
+                  tp->write_seq-tp->snd_una,
+                  (sp->sk_state == TCP_LISTEN) ? sp->sk_ack_backlog : (tp->rcv_nxt - tp->copied_seq),
                   timer_active,
                   jiffies_to_clock_t(timer_expires - jiffies),
                   icsk->icsk_retransmits,