[PATCH net v4] sctp: socket: refactor sctp_skb_recv_datagram to use ERR_PTR
From: luoqing <hidden>
Date: 2026-07-20 08:22:23
Also in:
linux-sctp, lkml
Subsystem:
networking [general], sctp protocol, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Marcelo Ricardo Leitner, Xin Long, Linus Torvalds
From: Qing Luo <redacted> The err output parameter in sctp_skb_recv_datagram() is passed to callers but never validated, making error reporting unreliable. Remove it and use ERR_PTR to encode errors directly in the return value, which is the standard kernel pattern for this case. Signed-off-by: Qing Luo <redacted> --- include/net/sctp/sctp.h | 2 +- net/sctp/socket.c | 20 ++++++++++---------- net/sctp/ulpevent.c | 5 ++--- 3 files changed, 13 insertions(+), 14 deletions(-)
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index d50c27812504..b86d50d6b146 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h@@ -97,7 +97,7 @@ void sctp_sock_rfree(struct sk_buff *skb); extern struct percpu_counter sctp_sockets_allocated; int sctp_asconf_mgmt(struct sctp_sock *, struct sctp_sockaddr_entry *); -struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int *); +struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags); typedef int (*sctp_callback_t)(struct sctp_endpoint *, struct sctp_transport *, void *); void sctp_transport_walk_start(struct rhashtable_iter *iter);
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index c7b9e325ec1c..2deaa498e6cf 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c@@ -2123,9 +2123,11 @@ static int sctp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, goto out; } - skb = sctp_skb_recv_datagram(sk, flags, &err); - if (!skb) + skb = sctp_skb_recv_datagram(sk, flags); + if (IS_ERR(skb)) { + err = PTR_ERR(skb); goto out; + } /* Get the total length of the skb including any skb's in the * frag_list.
@@ -9082,7 +9084,7 @@ static int sctp_wait_for_packet(struct sock *sk, int *err, long *timeo_p) * Note: This is pretty much the same routine as in core/datagram.c * with a few changes to make lksctp work. */ -struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags, int *err) +struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags) { int error; struct sk_buff *skb;
@@ -9117,21 +9119,19 @@ struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags, int *err) if (error) goto no_packet; - if (sk->sk_shutdown & RCV_SHUTDOWN) + if (sk->sk_shutdown & RCV_SHUTDOWN) { + error = 0; break; - + } /* User doesn't want to wait. */ error = -EAGAIN; if (!timeo) goto no_packet; - } while (sctp_wait_for_packet(sk, err, &timeo) == 0); - - return NULL; + } while (sctp_wait_for_packet(sk, &error, &timeo) == 0); no_packet: - *err = error; - return NULL; + return ERR_PTR(error); } /* If sndbuf has changed, wake up per association sndbuf waiters. */
diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c
index 8920ca92a011..21ae0adbaeef 100644
--- a/net/sctp/ulpevent.c
+++ b/net/sctp/ulpevent.c@@ -1061,10 +1061,9 @@ void sctp_ulpevent_read_nxtinfo(const struct sctp_ulpevent *event, struct sock *sk) { struct sk_buff *skb; - int err; - skb = sctp_skb_recv_datagram(sk, MSG_PEEK | MSG_DONTWAIT, &err); - if (skb != NULL) { + skb = sctp_skb_recv_datagram(sk, MSG_PEEK | MSG_DONTWAIT); + if (!IS_ERR_OR_NULL(skb)) { __sctp_ulpevent_read_nxtinfo(sctp_skb2event(skb), msghdr, skb); /* Just release refcount here. */
--
2.25.1
>> I think it's used at [1] in sctp_recvmsg():
>>
>> skb = sctp_skb_recv_datagram(sk, flags, &err);
>> if (!skb)
>> goto out;
> Would it make more sense to ERR_PTR() etc ?
>
>
> David
Yes, you are right. The current implementation returns a negative error
code directly via err, but it would be cleaner to use ERR_PTR() to
unify the error path with other datagram receivers.
I will refactor this part in v4:
>
>
>> ...
>>
>> out:
>> release_sock(sk);
>> return err; <------ [1]