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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: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Guillaume Nault 2019-03-19 16:05:44 +01:00 committed by David S. Miller
parent 56dc6d6355
commit 9403cf2302
3 changed files with 17 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/net/request_sock.h
View File

@ -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))

17
net/ipv4/syncookies.c
View File

@ -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)) {
bh_unlock_sock(child);
sock_put(child);
child = NULL;
reqsk_put(req);
}
} else {
reqsk_free(req);
if (inet_csk_reqsk_queue_add(sk, req, child))
return child;
bh_unlock_sock(child);
sock_put(child);
}
return child;
__reqsk_free(req);
return NULL;
}
EXPORT_SYMBOL(tcp_get_cookie_sock);

5
net/ipv4/tcp_input.c
View File

@ -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;