tcp: fix bug in listening_get_next()

commit a8b690f98baf9fb19 (tcp: Fix slowness in read /proc/net/tcp)
introduced a bug in handling of SYN_RECV sockets.

st->offset represents number of sockets found since beginning of
listening_hash[st->bucket].

We should not reset st->offset when iterating through
syn_table[st->sbucket], or else if more than ~25 sockets (if
PAGE_SIZE=4096) are in SYN_RECV state, we exit from listening_get_next()
with a too small st->offset

Next time we enter tcp_seek_last_pos(), we are not able to seek past
already found sockets.

Reported-by: PK <runningdoglackey@yahoo.com>
CC: Tom Herbert <therbert@google.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 856f684..02f583b 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1994,7 +1994,6 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
                                }
                                req = req->dl_next;
                        }
-                       st->offset = 0;
                        if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
                                break;
 get_req: