While debugging a TCP server hang issue, we noticed that currently there is
no way for a user to find 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. I think these
fields do not mean much for listening sockets and they are always zero. So why
not use one of these fields(rx_queue) to export the accept queue len for
listening
sockets?
The attached patch implements this, but it only works with /proc/net/tcp and
/proc/net/tcp6.
In order to support this with netstat/ss that use netlink mechanism to
get the socket info, i think we need to extend tcp_info to add this field.
Can this be done in a backward compatible way?
Anyway, i think it is useful to have this value exported via /proc.
Thanks
Sridhar
Signed-off-by: Sridhar Samudrala <[EMAIL PROTECTED]>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 25ecc6e..4c6ef47 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1726,7 +1726,8 @@ static void get_tcp4_sock(struct sock *s
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
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1469,7 +1469,8 @@ static void get_tcp6_sock(struct seq_fil
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,
-
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