On 10/17, Cong Wang wrote:
From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Technically we don't need lock the sock in the psock work, but we
need to prevent this work running in parallel with sock_map_close().
With this, we no longer need to wait for the psock->work synchronously,
because when we reach here, either this work is still pending, or
blocking on the lock_sock(), or it is completed. We only need to cancel
the first case asynchronously, and we need to bail out the second case
quickly by checking SK_PSOCK_TX_ENABLED bit.
Fixes: 799aa7f98d53 ("skmsg: Avoid lock_sock() in sk_psock_backlog()")
Reported-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
This seems to remove the splat for me:
Tested-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
The patch looks good, but I'll leave the review to Jakub/John.
---
include/linux/skmsg.h | 2 +-
net/core/skmsg.c | 19 +++++++++++++------
net/core/sock_map.c | 4 ++--
3 files changed, 16 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 ca70525621c7..c329e71ea924 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -647,6 +647,11 @@ static void sk_psock_backlog(struct work_struct
*work)
int ret;
mutex_lock(&psock->work_mutex);
+ lock_sock(psock->sk);
+
+ if (!sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED))
+ goto end;
+
if (unlikely(state->skb)) {
spin_lock_bh(&psock->ingress_lock);
skb = state->skb;
@@ -672,9 +677,12 @@ static void sk_psock_backlog(struct work_struct
*work)
skb_bpf_redirect_clear(skb);
do {
ret = -EIO;
- if (!sock_flag(psock->sk, SOCK_DEAD))
+ if (!sock_flag(psock->sk, SOCK_DEAD)) {
+ release_sock(psock->sk);
ret = sk_psock_handle_skb(psock, skb, off,
len, ingress);
+ lock_sock(psock->sk);
+ }
if (ret <= 0) {
if (ret == -EAGAIN) {
sk_psock_skb_state(psock, state, skb,
@@ -695,6 +703,7 @@ static void sk_psock_backlog(struct work_struct *work)
kfree_skb(skb);
}
end:
+ release_sock(psock->sk);
mutex_unlock(&psock->work_mutex);
}
@@ -803,16 +812,14 @@ 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);
+ cancel_work(&psock->work);
}
static void sk_psock_done_strp(struct sk_psock *psock);
@@ -850,7 +857,7 @@ 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 a660baedd9e7..d4e11d7f459c 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);
}
@@ -1619,7 +1619,7 @@ 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_stop(psock);
sk_psock_put(sk, psock);
release_sock(sk);
saved_close(sk, timeout);
--
2.34.1
