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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4954a2eddb8sm137976275e9.14.2026.07.17.11.19.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Jul 2026 11:19:14 -0700 (PDT) Date: Fri, 17 Jul 2026 19:19:13 +0100 From: David Laight To: Xin Long Cc: luoqing , jedrzej.jagielski@intel.com, davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-sctp@vger.kernel.org, luoqing@kylinos.cn, marcelo.leitner@gmail.com, netdev@vger.kernel.org, pabeni@redhat.com Subject: Re: [PATCH net v3] sctp: socket: remove unused 'err' parameter from sctp_skb_recv_datagram Message-ID: <20260717191913.490e5d80@pumpkin> In-Reply-To: References: <20260717082048.948262-1-l1138897701@163.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Fri, 17 Jul 2026 11:10:21 -0400 Xin Long wrote: > On Fri, Jul 17, 2026 at 4:21=E2=80=AFAM luoqing wro= te: > > > > From: luoqing > > > > The 'err' parameter in sctp_skb_recv_datagram() is never used by any > > of its callers. Both sctp_recvmsg() and sctp_ulpevent_read_nxtinfo() > > pass the address of a local variable but never check its value after > > the function returns, rendering the parameter completely useless. > > > > Remove the unused parameter to simplify the function signature and > > eliminate dead code. > > > > Signed-off-by: luoqing > > --- > > include/net/sctp/sctp.h | 2 +- > > net/sctp/socket.c | 10 +++------- > > net/sctp/ulpevent.c | 3 +-- > > 3 files changed, 5 insertions(+), 10 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_tra= nsport *, void *); > > void sctp_transport_walk_start(struct rhashtable_iter *iter); > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > > index c7b9e325ec1c..3804382d78e0 100644 > > --- a/net/sctp/socket.c > > +++ b/net/sctp/socket.c > > @@ -2123,7 +2123,7 @@ static int sctp_recvmsg(struct sock *sk, struct m= sghdr *msg, size_t len, > > goto out; > > } > > > > - skb =3D sctp_skb_recv_datagram(sk, flags, &err); > > + skb =3D sctp_skb_recv_datagram(sk, flags); > > if (!skb) > > goto out; > > > > @@ -9082,7 +9082,7 @@ 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; > > @@ -9120,17 +9120,13 @@ struct sk_buff *sctp_skb_recv_datagram(struct s= ock *sk, int flags, int *err) > > if (sk->sk_shutdown & RCV_SHUTDOWN) > > break; > > > > - > > /* User doesn't want to wait. */ > > error =3D -EAGAIN; > > if (!timeo) > > goto no_packet; > > - } while (sctp_wait_for_packet(sk, err, &timeo) =3D=3D 0); > > - > > - return NULL; > > + } while (sctp_wait_for_packet(sk, &error, &timeo) =3D=3D 0); > > > > no_packet: > > - *err =3D error; > > return NULL; > > } > > > > diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c > > index 8920ca92a011..8ed51a15c3a4 100644 > > --- a/net/sctp/ulpevent.c > > +++ b/net/sctp/ulpevent.c > > @@ -1061,9 +1061,8 @@ void sctp_ulpevent_read_nxtinfo(const struct sctp= _ulpevent *event, > > struct sock *sk) > > { > > struct sk_buff *skb; > > - int err; > > > > - skb =3D sctp_skb_recv_datagram(sk, MSG_PEEK | MSG_DONTWAIT, &er= r); > > + skb =3D sctp_skb_recv_datagram(sk, MSG_PEEK | MSG_DONTWAIT); > > if (skb !=3D NULL) { > > __sctp_ulpevent_read_nxtinfo(sctp_skb2event(skb), > > msghdr, skb); > > -- > > 2.25.1 > > =20 > I think it's used at [1] in sctp_recvmsg(): >=20 > skb =3D sctp_skb_recv_datagram(sk, flags, &err); > if (!skb) > goto out; Would it make more sense to ERR_PTR() etc ? David > ... >=20 > out: > release_sock(sk); > return err; <------ [1] >=20 > Thanks. >=20