Commit 9652dc2e authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: relax listening_hash operations 



softirq handlers use RCU protection to lookup listeners,
and write operations all happen from process context.
We do not need to block BH for dump operations.

Also SYN_RECV since request sockets are stored in the ehash table :

 1) inet_diag_dump_icsk() no longer need to clear
    cb->args[3] and cb->args[4] that were used as cursors while
    iterating the old per listener hash table.

 2) Also factorize a test : No need to scan listening_hash[]
    if r->id.idiag_dport is not zero.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 25c07e2c

net/ipv4/inet_diag.c

+4 −12
Original line number Diff line number Diff line
@@ -863,7 +863,7 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb, 
	s_num = num = cb->args[2];



	if (cb->args[0] == 0) {

		if (!(idiag_states & TCPF_LISTEN))

		if (!(idiag_states & TCPF_LISTEN) || r->id.idiag_dport)

			goto skip_listen_ht;



		for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
@@ -872,7 +872,7 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb, 


			num = 0;

			ilb = &hashinfo->listening_hash[i];

			spin_lock_bh(&ilb->lock);

			spin_lock(&ilb->lock);

			sk_for_each(sk, &ilb->head) {

				struct inet_sock *inet = inet_sk(sk);
@@ -892,26 +892,18 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb, 
				    r->id.idiag_sport)

					goto next_listen;



				if (r->id.idiag_dport ||

				    cb->args[3] > 0)

					goto next_listen;



				if (inet_csk_diag_dump(sk, skb, cb, r,

						       bc, net_admin) < 0) {

					spin_unlock_bh(&ilb->lock);

					spin_unlock(&ilb->lock);

					goto done;

				}



next_listen:

				cb->args[3] = 0;

				cb->args[4] = 0;

				++num;

			}

			spin_unlock_bh(&ilb->lock);

			spin_unlock(&ilb->lock);



			s_num = 0;

			cb->args[3] = 0;

			cb->args[4] = 0;

		}

skip_listen_ht:

		cb->args[0] = 1;

net/ipv4/tcp_ipv4.c

+3 −3
Original line number Diff line number Diff line
@@ -1893,7 +1893,7 @@ static void *listening_get_next(struct seq_file *seq, void *cur) 
	if (!sk) {

get_head:

		ilb = &tcp_hashinfo.listening_hash[st->bucket];

		spin_lock_bh(&ilb->lock);

		spin_lock(&ilb->lock);

		sk = sk_head(&ilb->head);

		st->offset = 0;

		goto get_sk;
@@ -1911,7 +1911,7 @@ get_sk: 
			return sk;

		icsk = inet_csk(sk);

	}

	spin_unlock_bh(&ilb->lock);

	spin_unlock(&ilb->lock);

	st->offset = 0;

	if (++st->bucket < INET_LHTABLE_SIZE)

		goto get_head;
@@ -2119,7 +2119,7 @@ static void tcp_seq_stop(struct seq_file *seq, void *v) 
	switch (st->state) {

	case TCP_SEQ_STATE_LISTENING:

		if (v != SEQ_START_TOKEN)

			spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);

			spin_unlock(&tcp_hashinfo.listening_hash[st->bucket].lock);

		break;

	case TCP_SEQ_STATE_ESTABLISHED:

		if (v)

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