Commit 9403cf23 authored by Guillaume Nault's avatar Guillaume Nault Committed by David S. Miller
Browse files

tcp: free request sock directly upon TFO or syncookies error 



Since the request socket is created locally, it'd make more sense to
use reqsk_free() instead of reqsk_put() in TFO and syncookies' error
path.

However, tcp_get_cookie_sock() may set ->rsk_refcnt before freeing the
socket; tcp_conn_request() may also have non-null ->rsk_refcnt because
of tcp_try_fastopen(). In both cases 'req' hasn't been exposed
to the outside world and is safe to free immediately, but that'd
trigger the WARN_ON_ONCE in reqsk_free().

Define __reqsk_free() for these situations where we know nobody's
referencing the socket, even though ->rsk_refcnt might be non-null.
Now we can consolidate the error path of tcp_get_cookie_sock() and
tcp_conn_request().

Signed-off-by: default avatarGuillaume Nault <gnault@redhat.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 56dc6d63

include/net/request_sock.h

+7 −3
Original line number Diff line number Diff line
@@ -106,10 +106,8 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener, 
	return req;

}



static inline void reqsk_free(struct request_sock *req)

static inline void __reqsk_free(struct request_sock *req)

{

	WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);



	req->rsk_ops->destructor(req);

	if (req->rsk_listener)

		sock_put(req->rsk_listener);
@@ -117,6 +115,12 @@ static inline void reqsk_free(struct request_sock *req) 
	kmem_cache_free(req->rsk_ops->slab, req);

}



static inline void reqsk_free(struct request_sock *req)

{

	WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);

	__reqsk_free(req);

}



static inline void reqsk_put(struct request_sock *req)

{

	if (refcount_dec_and_test(&req->rsk_refcnt))

net/ipv4/syncookies.c

+8 −9
Original line number Diff line number Diff line
@@ -216,16 +216,15 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 
		refcount_set(&req->rsk_refcnt, 1);

		tcp_sk(child)->tsoffset = tsoff;

		sock_rps_save_rxhash(child, skb);

		if (!inet_csk_reqsk_queue_add(sk, req, child)) {

		if (inet_csk_reqsk_queue_add(sk, req, child))

			return child;



		bh_unlock_sock(child);

		sock_put(child);

			child = NULL;

			reqsk_put(req);

		}

	} else {

		reqsk_free(req);

	}

	return child;

	__reqsk_free(req);



	return NULL;

}

EXPORT_SYMBOL(tcp_get_cookie_sock);

net/ipv4/tcp_input.c

+2 −3
Original line number Diff line number Diff line
@@ -6502,8 +6502,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, 
			reqsk_fastopen_remove(fastopen_sk, req, false);

			bh_unlock_sock(fastopen_sk);

			sock_put(fastopen_sk);

			reqsk_put(req);

			goto drop;

			goto drop_and_free;

		}

		sk->sk_data_ready(sk);

		bh_unlock_sock(fastopen_sk);
@@ -6527,7 +6526,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, 
drop_and_release:

	dst_release(dst);

drop_and_free:

	reqsk_free(req);

	__reqsk_free(req);

drop:

	tcp_listendrop(sk);

	return 0;

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