From: Cong Wang cong.wang@bytedance.com
[ Upstream commit 8bbabb3fddcd0f858be69ed5abc9b470a239d6f2 ]
Stanislav reported a lockdep warning, which is caused by the cancel_work_sync() called inside sock_map_close(), as analyzed below by Jakub:
psock->work.func = sk_psock_backlog() ACQUIRE psock->work_mutex sk_psock_handle_skb() skb_send_sock() __skb_send_sock() sendpage_unlocked() kernel_sendpage() sock->ops->sendpage = inet_sendpage() sk->sk_prot->sendpage = tcp_sendpage() ACQUIRE sk->sk_lock tcp_sendpage_locked() RELEASE sk->sk_lock RELEASE psock->work_mutex
sock_map_close() ACQUIRE sk->sk_lock sk_psock_stop() sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED) cancel_work_sync() __cancel_work_timer() __flush_work() // wait for psock->work to finish RELEASE sk->sk_lock
We can move the cancel_work_sync() out of the sock lock protection, but still before saved_close() was called.
Fixes: 799aa7f98d53 ("skmsg: Avoid lock_sock() in sk_psock_backlog()") Reported-by: Stanislav Fomichev sdf@google.com Signed-off-by: Cong Wang cong.wang@bytedance.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Tested-by: Jakub Sitnicki jakub@cloudflare.com Acked-by: John Fastabend john.fastabend@gmail.com Acked-by: Jakub Sitnicki jakub@cloudflare.com Link: https://lore.kernel.org/bpf/20221102043417.279409-1-xiyou.wangcong@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/skmsg.h | 2 +- net/core/skmsg.c | 7 ++----- net/core/sock_map.c | 7 ++++--- 3 files changed, 7 insertions(+), 9 deletions(-)
diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index 48f4b645193b..70d6cb94e580 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -376,7 +376,7 @@ static inline void sk_psock_report_error(struct sk_psock *psock, int err) }
struct sk_psock *sk_psock_init(struct sock *sk, int node); -void sk_psock_stop(struct sk_psock *psock, bool wait); +void sk_psock_stop(struct sk_psock *psock);
#if IS_ENABLED(CONFIG_BPF_STREAM_PARSER) int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock); diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 1efdc47a999b..e6b9ced3eda8 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -803,16 +803,13 @@ static void sk_psock_link_destroy(struct sk_psock *psock) } }
-void sk_psock_stop(struct sk_psock *psock, bool wait) +void sk_psock_stop(struct sk_psock *psock) { spin_lock_bh(&psock->ingress_lock); sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED); sk_psock_cork_free(psock); __sk_psock_zap_ingress(psock); spin_unlock_bh(&psock->ingress_lock); - - if (wait) - cancel_work_sync(&psock->work); }
static void sk_psock_done_strp(struct sk_psock *psock); @@ -850,7 +847,7 @@ void sk_psock_drop(struct sock *sk, struct sk_psock *psock) sk_psock_stop_verdict(sk, psock); write_unlock_bh(&sk->sk_callback_lock);
- sk_psock_stop(psock, false); + sk_psock_stop(psock);
INIT_RCU_WORK(&psock->rwork, sk_psock_destroy); queue_rcu_work(system_wq, &psock->rwork); diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 9a9fb9487d63..632df0c52562 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -1596,7 +1596,7 @@ void sock_map_destroy(struct sock *sk) saved_destroy = psock->saved_destroy; sock_map_remove_links(sk, psock); rcu_read_unlock(); - sk_psock_stop(psock, false); + sk_psock_stop(psock); sk_psock_put(sk, psock); saved_destroy(sk); } @@ -1619,9 +1619,10 @@ void sock_map_close(struct sock *sk, long timeout) saved_close = psock->saved_close; sock_map_remove_links(sk, psock); rcu_read_unlock(); - sk_psock_stop(psock, true); - sk_psock_put(sk, psock); + sk_psock_stop(psock); release_sock(sk); + cancel_work_sync(&psock->work); + sk_psock_put(sk, psock); saved_close(sk, timeout); } EXPORT_SYMBOL_GPL(sock_map_close);