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Commit fb3477c0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: do not block bh during prequeue processing 



AFAIK, nothing in current TCP stack absolutely wants BH
being disabled once socket is owned by a thread running in
process context.

As mentioned in my prior patch ("tcp: give prequeue mode some care"),
processing a batch of packets might take time, better not block BH
at all.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c10d9310

net/ipv4/tcp.c

+0 −4
Original line number Diff line number Diff line
@@ -1449,12 +1449,8 @@ static void tcp_prequeue_process(struct sock *sk) 


	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPREQUEUED);



	/* RX process wants to run with disabled BHs, though it is not

	 * necessary */

	local_bh_disable();

	while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)

		sk_backlog_rcv(sk, skb);

	local_bh_enable();



	/* Clear memory counter. */

	tp->ucopy.memory = 0;

net/ipv4/tcp_input.c

+2 −28
Original line number Diff line number Diff line
@@ -4611,14 +4611,12 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) 


			__set_current_state(TASK_RUNNING);



			local_bh_enable();

			if (!skb_copy_datagram_msg(skb, 0, tp->ucopy.msg, chunk)) {

				tp->ucopy.len -= chunk;

				tp->copied_seq += chunk;

				eaten = (chunk == skb->len);

				tcp_rcv_space_adjust(sk);

			}

			local_bh_disable();

		}



		if (eaten <= 0) {
@@ -5134,7 +5132,6 @@ static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen) 
	int chunk = skb->len - hlen;

	int err;



	local_bh_enable();

	if (skb_csum_unnecessary(skb))

		err = skb_copy_datagram_msg(skb, hlen, tp->ucopy.msg, chunk);

	else
@@ -5146,32 +5143,9 @@ static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen) 
		tcp_rcv_space_adjust(sk);

	}



	local_bh_disable();

	return err;

}



static __sum16 __tcp_checksum_complete_user(struct sock *sk,

					    struct sk_buff *skb)

{

	__sum16 result;



	if (sock_owned_by_user(sk)) {

		local_bh_enable();

		result = __tcp_checksum_complete(skb);

		local_bh_disable();

	} else {

		result = __tcp_checksum_complete(skb);

	}

	return result;

}



static inline bool tcp_checksum_complete_user(struct sock *sk,

					     struct sk_buff *skb)

{

	return !skb_csum_unnecessary(skb) &&

	       __tcp_checksum_complete_user(sk, skb);

}



/* Does PAWS and seqno based validation of an incoming segment, flags will

 * play significant role here.

 */
@@ -5386,7 +5360,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 
				}

			}

			if (!eaten) {

				if (tcp_checksum_complete_user(sk, skb))

				if (tcp_checksum_complete(skb))

					goto csum_error;



				if ((int)skb->truesize > sk->sk_forward_alloc)
@@ -5430,7 +5404,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 
	}



slow_path:

	if (len < (th->doff << 2) || tcp_checksum_complete_user(sk, skb))

	if (len < (th->doff << 2) || tcp_checksum_complete(skb))

		goto csum_error;



	if (!th->ack && !th->rst && !th->syn)