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inet: add proper refcounting to request sock

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reqsk_put() is the generic function that should be used
to release a refcount (and automatically call reqsk_free())

reqsk_free() might be called if refcount is known to be 0
or undefined.

refcnt is set to one in inet_csk_reqsk_queue_add()

As request socks are not yet in global ehash table,
I added temporary debugging checks in reqsk_put() and reqsk_free()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-03-15 21:12:16 -07:00 • committed by David S. Miller
commit 13854e5a60
7 changed files with 29 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

5
include/net/inet_connection_sock.h
View file

@ -275,6 +275,11 @@ static inline void inet_csk_reqsk_queue_add(struct sock *sk,
struct sock *child)
{
reqsk_queue_add(&inet_csk(sk)->icsk_accept_queue, req, sk, child);
/* before letting lookups find us, make sure all req fields
* are committed to memory.
*/
smp_wmb();
atomic_set(&req->rsk_refcnt, 1);
}
void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,

5
include/net/inet_sock.h
View file

@ -255,6 +255,11 @@ static inline struct request_sock *inet_reqsk_alloc(struct request_sock_ops *ops
ireq->opt = NULL;
atomic64_set(&ireq->ir_cookie, 0);
ireq->ireq_state = TCP_NEW_SYN_RECV;
/* Following is temporary. It is coupled with debugging
* helpers in reqsk_put() & reqsk_free()
*/
atomic_set(&ireq->ireq_refcnt, 0);
}
return req;

13
include/net/request_sock.h
View file

@ -82,19 +82,20 @@ static inline struct request_sock *inet_reqsk(struct sock *sk)
return (struct request_sock *)sk;
}
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)
{
/* temporary debugging */
WARN_ON_ONCE(atomic_read(&req->rsk_refcnt) != 0);
req->rsk_ops->destructor(req);
__reqsk_free(req);
kmem_cache_free(req->rsk_ops->slab, req);
}
static inline void reqsk_put(struct request_sock *req)
{
/* temporary debugging, until req sock are put into ehash table */
WARN_ON_ONCE(atomic_read(&req->rsk_refcnt) != 1);
if (atomic_dec_and_test(&req->rsk_refcnt))
reqsk_free(req);
}

4
net/core/request_sock.c
View file

@ -103,7 +103,7 @@ void reqsk_queue_destroy(struct request_sock_queue *queue)
while ((req = lopt->syn_table[i]) != NULL) {
lopt->syn_table[i] = req->dl_next;
lopt->qlen--;
reqsk_free(req);
reqsk_put(req);
}
}
}
@ -180,7 +180,7 @@ void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
*/
spin_unlock_bh(&fastopenq->lock);
sock_put(lsk);
reqsk_free(req);
reqsk_put(req);
return;
}
/* Wait for 60secs before removing a req that has triggered RST.

8
net/ipv4/inet_connection_sock.c
View file

@ -340,7 +340,7 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
out:
release_sock(sk);
if (req)
__reqsk_free(req);
reqsk_put(req);
return newsk;
out_err:
newsk = NULL;
@ -635,7 +635,7 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
/* Drop this request */
inet_csk_reqsk_queue_unlink(parent, req, reqp);
reqsk_queue_removed(queue, req);
reqsk_free(req);
reqsk_put(req);
continue;
}
reqp = &req->dl_next;
@ -837,7 +837,7 @@ void inet_csk_listen_stop(struct sock *sk)
sock_put(child);
sk_acceptq_removed(sk);
__reqsk_free(req);
reqsk_put(req);
}
if (queue->fastopenq != NULL) {
/* Free all the reqs queued in rskq_rst_head. */
@ -847,7 +847,7 @@ void inet_csk_listen_stop(struct sock *sk)
spin_unlock_bh(&queue->fastopenq->lock);
while ((req = acc_req) != NULL) {
acc_req = req->dl_next;
__reqsk_free(req);
reqsk_put(req);
}
}
WARN_ON(sk->sk_ack_backlog);

10
net/ipv4/syncookies.c
View file

@ -219,9 +219,9 @@ int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
}
EXPORT_SYMBOL_GPL(__cookie_v4_check);
static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst)
static struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct sock *child;
@ -357,7 +357,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
ireq->opt = tcp_v4_save_options(skb);
if (security_inet_conn_request(sk, skb, req)) {
reqsk_free(req);
reqsk_put(req);
goto out;
}
@ -378,7 +378,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
security_req_classify_flow(req, flowi4_to_flowi(&fl4));
rt = ip_route_output_key(sock_net(sk), &fl4);
if (IS_ERR(rt)) {
reqsk_free(req);
reqsk_put(req);
goto out;
}

2
net/ipv4/tcp_fastopen.c
View file

@ -253,7 +253,7 @@ static bool tcp_fastopen_queue_check(struct sock *sk)
fastopenq->rskq_rst_head = req1->dl_next;
fastopenq->qlen--;
spin_unlock(&fastopenq->lock);
reqsk_free(req1);
reqsk_put(req1);
}
return true;
}