From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Tested-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
Acked-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20221102043417.279409-1-xiyou.wangcong@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.35.1
