tcp: no longer hold ehash lock while calling tcp_get_info()

We had various problems in the past in tcp_get_info() and used
specific synchronization to avoid deadlocks.

We would like to add more instrumentation points for TCP, and
avoiding grabing socket lock in tcp_getinfo() was too costly.

Being able to lock the socket allows to provide consistent set
of fields.

inet_diag_dump_icsk() can make sure ehash locks are not
held any more when tcp_get_info() is called.

We can remove syncp added in commit d654976cbf85
("tcp: fix a potential deadlock in tcp_get_info()"), but we need
to use lock_sock_fast() instead of spin_lock_bh() since TCP input
path can now be run from process context.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 4 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f2c59c8e57ff..a70046fea0e8 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3351,9 +3351,7 @@ static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
 	u32 delta = ack - tp->snd_una;
 
 	sock_owned_by_me((struct sock *)tp);
-	u64_stats_update_begin_raw(&tp->syncp);
 	tp->bytes_acked += delta;
-	u64_stats_update_end_raw(&tp->syncp);
 	tp->snd_una = ack;
 }
 
@@ -3363,9 +3361,7 @@ static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
 	u32 delta = seq - tp->rcv_nxt;
 
 	sock_owned_by_me((struct sock *)tp);
-	u64_stats_update_begin_raw(&tp->syncp);
 	tp->bytes_received += delta;
-	u64_stats_update_end_raw(&tp->syncp);
 	tp->rcv_nxt = seq;
 }