From nobody Tue Feb 10 04:02:16 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 469EF350D4C; Sun, 1 Feb 2026 14:33:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769956421; cv=none; b=C/O85JeoNKmzBLpwUxEVqp9/XbeMtu7NcNhzbD5+Tif4n0+M2kmrtmXx9+2eHNSSEOtEevoR/bZdxS7VH2koDuXtipv6GmlWKhXYsL3QeHKFJ1h31WmYCyVykarV8ZN1lX+TdB1JmUhQFqKnOIh65bf8pG0xyiYa0fwVrcQNZF8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769956421; c=relaxed/simple; bh=xmJQsKeAEXPc2KJlPZ6gOTv4w+iS/oQIEeKdQFJ06oQ=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ZvaIf50cY9MYus3FB5LjX9kmgjPJ33FacSGitqILETBE9tZRCuFzyexzOnVk3A441sS2wfLBsk4+A54Ao5n4KVI7iVNdQEwCTN14aqg48qV0nNYZt/ropEz/5GxoCQrWRilXE2Ssvv6Bd2OEoc+13kDtYQk8vWNxpgYgCknAShY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u6ViClRF; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u6ViClRF" Received: by smtp.kernel.org (Postfix) with ESMTPS id 249A7C4CEF7; Sun, 1 Feb 2026 14:33:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769956421; bh=xmJQsKeAEXPc2KJlPZ6gOTv4w+iS/oQIEeKdQFJ06oQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=u6ViClRF1MkMqBzT1gc6iLAbW1u+CDhaqY1WAxDWQRSN91SgE3iNoM6UuqHazpbYs NFGY+ou425TksXEm5kuPx57IJg+y27HJ8/oY9MIPpAL2u4p9huc1nZWAxHB0QCIKZW kOFbtoxhJXpqQNb2kC0C0S5MrJCN5AfvTq0bac7S7q/DfKmuOIRV694SDSrh7GOr+X wZBE/NH2CHD23gyo04RxOUh5KafyKWlcanGjZbWc5hbF3bMyFSkY2kSU2whliD94I/ 0S9b5G3oaC4HOE18yeqeV76vX3GkpFl9/J42zt+kPwekBKK5qQsu2yekyhGRzEmqEP Mcxdejb/2MxSg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A910E6528A; Sun, 1 Feb 2026 14:33:41 +0000 (UTC) From: Oliver Hartkopp via B4 Relay Date: Sun, 01 Feb 2026 15:33:20 +0100 Subject: [PATCH net-next v8 5/6] can: remove private CAN skb headroom infrastructure 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 Message-Id: <20260201-can_skb_ext-v8-5-3635d790fe8b@hartkopp.net> References: <20260201-can_skb_ext-v8-0-3635d790fe8b@hartkopp.net> In-Reply-To: <20260201-can_skb_ext-v8-0-3635d790fe8b@hartkopp.net> To: Marc Kleine-Budde , Vincent Mailhol , Oliver Hartkopp , Robin van der Gracht , Oleksij Rempel , kernel@pengutronix.de, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: linux-can@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org X-Mailer: b4 0.15-dev-47773 X-Developer-Signature: v=1; a=ed25519-sha256; t=1769956418; l=12992; i=socketcan@hartkopp.net; s=20260128; h=from:subject:message-id; bh=8latfQ42+KWkvgJX7eiG4SXUR1zyD7tvI5xRV1vgLaY=; b=hTNTqc0V4X7aLwK9oZlXmHCU2cF0k5pUrxP+Luth3VLtJ9GgN6RE2C5cYpg/+19KIipgwzmAw 6YK9hnDqjXeC6qc6QzUGsdgjdqPYDHifORACxeQAYbei5abLaAmk09n X-Developer-Key: i=socketcan@hartkopp.net; a=ed25519; pk=/gU/7/wBqak3kTsTeFbCCqUi9dnh+1i6ITEkfPj/BvU= X-Endpoint-Received: by B4 Relay for socketcan@hartkopp.net/20260128 with auth_id=620 X-Original-From: Oliver Hartkopp Reply-To: socketcan@hartkopp.net From: Oliver Hartkopp This patch removes struct can_skb_priv which was stored at skb->head and the can_skb_reserve() helper which was used to shift skb->head. Signed-off-by: Marc Kleine-Budde Signed-off-by: Oliver Hartkopp --- drivers/net/can/dev/skb.c | 31 +++++++++---------------------- include/linux/can/skb.h | 31 ------------------------------- net/can/bcm.c | 7 ++----- net/can/isotp.c | 12 ++++-------- net/can/j1939/socket.c | 4 +--- net/can/j1939/transport.c | 7 ++----- net/can/raw.c | 5 ++--- 7 files changed, 20 insertions(+), 77 deletions(-) diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c index 408ee49abce1..95fcdc1026f8 100644 --- a/drivers/net/can/dev/skb.c +++ b/drivers/net/can/dev/skb.c @@ -204,40 +204,33 @@ void can_free_echo_skb(struct net_device *dev, unsign= ed int idx, } } EXPORT_SYMBOL_GPL(can_free_echo_skb); =20 /* fill common values for CAN sk_buffs */ -static void init_can_skb_reserve(struct sk_buff *skb) +static void init_can_skb(struct sk_buff *skb) { skb->pkt_type =3D PACKET_BROADCAST; skb->ip_summed =3D CHECKSUM_UNNECESSARY; - - skb_reset_mac_header(skb); - skb_reset_network_header(skb); - skb_reset_transport_header(skb); - - can_skb_reserve(skb); } =20 struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **c= f) { struct sk_buff *skb; struct can_skb_ext *csx; =20 - skb =3D netdev_alloc_skb(dev, sizeof(struct can_skb_priv) + - sizeof(struct can_frame)); + skb =3D netdev_alloc_skb(dev, sizeof(struct can_frame)); if (unlikely(!skb)) goto out_error_cc; =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); goto out_error_cc; } =20 skb->protocol =3D htons(ETH_P_CAN); - init_can_skb_reserve(skb); + init_can_skb(skb); csx->can_iif =3D dev->ifindex; =20 *cf =3D skb_put_zero(skb, sizeof(struct can_frame)); =20 return skb; @@ -253,23 +246,22 @@ struct sk_buff *alloc_canfd_skb(struct net_device *de= v, struct canfd_frame **cfd) { struct sk_buff *skb; struct can_skb_ext *csx; =20 - skb =3D netdev_alloc_skb(dev, sizeof(struct can_skb_priv) + - sizeof(struct canfd_frame)); + skb =3D netdev_alloc_skb(dev, sizeof(struct canfd_frame)); if (unlikely(!skb)) goto out_error_fd; =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); goto out_error_fd; } =20 skb->protocol =3D htons(ETH_P_CANFD); - init_can_skb_reserve(skb); + init_can_skb(skb); csx->can_iif =3D dev->ifindex; =20 *cfd =3D skb_put_zero(skb, sizeof(struct canfd_frame)); =20 /* set CAN FD flag by default */ @@ -292,23 +284,22 @@ struct sk_buff *alloc_canxl_skb(struct net_device *de= v, struct can_skb_ext *csx; =20 if (data_len < CANXL_MIN_DLEN || data_len > CANXL_MAX_DLEN) goto out_error_xl; =20 - skb =3D netdev_alloc_skb(dev, sizeof(struct can_skb_priv) + - CANXL_HDR_SIZE + data_len); + skb =3D netdev_alloc_skb(dev, CANXL_HDR_SIZE + data_len); if (unlikely(!skb)) goto out_error_xl; =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); goto out_error_xl; } =20 skb->protocol =3D htons(ETH_P_CANXL); - init_can_skb_reserve(skb); + init_can_skb(skb); csx->can_iif =3D dev->ifindex; =20 *cxl =3D skb_put_zero(skb, CANXL_HDR_SIZE + data_len); =20 /* set CAN XL flag and length information by default */ @@ -338,18 +329,14 @@ struct sk_buff *alloc_can_err_skb(struct net_device *= dev, struct can_frame **cf) return skb; } EXPORT_SYMBOL_GPL(alloc_can_err_skb); =20 /* Check for outgoing skbs that have not been created by the CAN subsystem= */ -static bool can_skb_headroom_valid(struct net_device *dev, struct sk_buff = *skb) +static bool can_skb_init_valid(struct net_device *dev, struct sk_buff *skb) { struct can_skb_ext *csx =3D can_skb_ext_find(skb); =20 - /* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */ - if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv))) - return false; - /* af_packet does not apply CAN skb specific settings */ if (skb->ip_summed =3D=3D CHECKSUM_NONE || !csx) { /* init CAN skb content */ if (!csx) { csx =3D can_skb_ext_add(skb); @@ -403,11 +390,11 @@ bool can_dropped_invalid_skb(struct net_device *dev, = struct sk_buff *skb) =20 default: goto inval_skb; } =20 - if (!can_skb_headroom_valid(dev, skb)) + if (!can_skb_init_valid(dev, skb)) goto inval_skb; =20 return false; =20 inval_skb: diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h index 68c0f24e6914..a70a02967071 100644 --- a/include/linux/can/skb.h +++ b/include/linux/can/skb.h @@ -36,41 +36,10 @@ struct sk_buff *alloc_canxl_skb(struct net_device *dev, unsigned int data_len); struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf); bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb); =20 -/* - * The struct can_skb_priv is used to transport additional information alo= ng - * with the stored struct can(fd)_frame that can not be contained in exist= ing - * struct sk_buff elements. - * N.B. that this information must not be modified in cloned CAN sk_buffs. - * To modify the CAN frame content or the struct can_skb_priv content - * skb_copy() needs to be used instead of skb_clone(). - */ - -/** - * struct can_skb_priv - private additional data inside CAN sk_buffs - * @ifindex: ifindex of the first interface the CAN frame appeared on - * @frame_len: length of CAN frame in data link layer - * @cf: align to the following CAN frame at skb->data - */ -struct can_skb_priv { - int ifindex; - unsigned int frame_len; - struct can_frame cf[]; -}; - -static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb) -{ - return (struct can_skb_priv *)(skb->head); -} - -static inline void can_skb_reserve(struct sk_buff *skb) -{ - skb_reserve(skb, sizeof(struct can_skb_priv)); -} - static inline struct can_skb_ext *can_skb_ext_add(struct sk_buff *skb) { struct can_skb_ext *csx =3D skb_ext_add(skb, SKB_EXT_CAN); =20 /* skb_ext_add() returns uninitialized space */ diff --git a/net/can/bcm.c b/net/can/bcm.c index f102d17e8619..b7324e9c955b 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -310,21 +310,20 @@ static void bcm_can_tx(struct bcm_op *op) if (!dev) { /* RFC: should this bcm_op remove itself here? */ return; } =20 - skb =3D alloc_skb(op->cfsiz + sizeof(struct can_skb_priv), gfp_any()); + skb =3D alloc_skb(op->cfsiz, gfp_any()); if (!skb) goto out; =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); goto out; } =20 - can_skb_reserve(skb); csx->can_iif =3D dev->ifindex; =20 skb_put_data(skb, cf, op->cfsiz); =20 /* send with loopback */ @@ -1331,22 +1330,20 @@ static int bcm_tx_send(struct msghdr *msg, int ifin= dex, struct sock *sk, =20 /* we need a real device to send frames */ if (!ifindex) return -ENODEV; =20 - skb =3D alloc_skb(cfsiz + sizeof(struct can_skb_priv), GFP_KERNEL); + skb =3D alloc_skb(cfsiz, GFP_KERNEL); if (!skb) return -ENOMEM; =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); return -ENOMEM; } =20 - can_skb_reserve(skb); - err =3D memcpy_from_msg(skb_put(skb, cfsiz), msg, cfsiz); if (err < 0) { kfree_skb(skb); return err; } diff --git a/net/can/isotp.c b/net/can/isotp.c index 164c4fbf3e23..da3b72e7afcc 100644 --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -218,11 +218,11 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 = flowstatus) struct can_skb_ext *csx; struct canfd_frame *ncf; struct isotp_sock *so =3D isotp_sk(sk); int can_send_ret; =20 - nskb =3D alloc_skb(so->ll.mtu + sizeof(struct can_skb_priv), gfp_any()); + nskb =3D alloc_skb(so->ll.mtu, gfp_any()); if (!nskb) return 1; =20 csx =3D can_skb_ext_add(nskb); if (!csx) { @@ -234,13 +234,11 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 = flowstatus) if (!dev) { kfree_skb(nskb); return 1; } =20 - can_skb_reserve(nskb); csx->can_iif =3D dev->ifindex; - nskb->dev =3D dev; can_skb_set_owner(nskb, sk); ncf =3D (struct canfd_frame *)nskb->data; skb_put_zero(nskb, so->ll.mtu); =20 @@ -778,11 +776,11 @@ static void isotp_send_cframe(struct isotp_sock *so) =20 dev =3D dev_get_by_index(sock_net(sk), so->ifindex); if (!dev) return; =20 - skb =3D alloc_skb(so->ll.mtu + sizeof(struct can_skb_priv), GFP_ATOMIC); + skb =3D alloc_skb(so->ll.mtu, GFP_ATOMIC); if (!skb) { dev_put(dev); return; } =20 @@ -791,11 +789,10 @@ static void isotp_send_cframe(struct isotp_sock *so) kfree_skb(skb); netdev_put(dev, NULL); return; } =20 - can_skb_reserve(skb); csx->can_iif =3D dev->ifindex; =20 cf =3D (struct canfd_frame *)skb->data; skb_put_zero(skb, so->ll.mtu); =20 @@ -1013,12 +1010,12 @@ static int isotp_sendmsg(struct socket *sock, struc= t msghdr *msg, size_t size) if (!dev) { err =3D -ENXIO; goto err_out_drop; } =20 - skb =3D sock_alloc_send_skb(sk, so->ll.mtu + sizeof(struct can_skb_priv), - msg->msg_flags & MSG_DONTWAIT, &err); + skb =3D sock_alloc_send_skb(sk, so->ll.mtu, msg->msg_flags & MSG_DONTWAIT, + &err); if (!skb) { dev_put(dev); goto err_out_drop; } =20 @@ -1028,11 +1025,10 @@ static int isotp_sendmsg(struct socket *sock, struc= t msghdr *msg, size_t size) netdev_put(dev, NULL); err =3D -ENOMEM; goto err_out_drop; } =20 - can_skb_reserve(skb); csx->can_iif =3D dev->ifindex; =20 so->tx.len =3D size; so->tx.idx =3D 0; =20 diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c index cc698a6dc363..0502b030d238 100644 --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -889,12 +889,11 @@ static struct sk_buff *j1939_sk_alloc_skb(struct net_= device *ndev, int ret; =20 skb =3D sock_alloc_send_skb(sk, size + sizeof(struct can_frame) - - sizeof(((struct can_frame *)NULL)->data) + - sizeof(struct can_skb_priv), + sizeof(((struct can_frame *)NULL)->data), msg->msg_flags & MSG_DONTWAIT, &ret); if (!skb) goto failure; =20 csx =3D can_skb_ext_add(skb); @@ -902,11 +901,10 @@ static struct sk_buff *j1939_sk_alloc_skb(struct net_= device *ndev, kfree_skb(skb); ret =3D -ENOMEM; goto failure; } =20 - can_skb_reserve(skb); csx->can_iif =3D ndev->ifindex; skb_reserve(skb, offsetof(struct can_frame, data)); =20 ret =3D memcpy_from_msg(skb_put(skb, size), msg, size); if (ret < 0) diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index 3456ef481799..2cbe94fc487a 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -593,23 +593,21 @@ sk_buff *j1939_tp_tx_dat_new(struct j1939_priv *priv, { struct sk_buff *skb; struct can_skb_ext *csx; struct j1939_sk_buff_cb *skcb; =20 - skb =3D alloc_skb(sizeof(struct can_frame) + sizeof(struct can_skb_priv), - GFP_ATOMIC); + skb =3D alloc_skb(sizeof(struct can_frame), GFP_ATOMIC); if (unlikely(!skb)) return ERR_PTR(-ENOMEM); =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); return ERR_PTR(-ENOMEM); } =20 skb->dev =3D priv->ndev; - can_skb_reserve(skb); csx->can_iif =3D priv->ndev->ifindex; /* reserve CAN header */ skb_reserve(skb, offsetof(struct can_frame, data)); =20 /* skb->cb must be large enough to hold a j1939_sk_buff_cb structure */ @@ -1546,22 +1544,21 @@ j1939_session *j1939_session_fresh_new(struct j1939= _priv *priv, struct sk_buff *skb; struct can_skb_ext *csx; struct j1939_sk_buff_cb *skcb; struct j1939_session *session; =20 - skb =3D alloc_skb(size + sizeof(struct can_skb_priv), GFP_ATOMIC); + skb =3D alloc_skb(size, GFP_ATOMIC); if (unlikely(!skb)) return NULL; =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); return NULL; } =20 skb->dev =3D priv->ndev; - can_skb_reserve(skb); csx->can_iif =3D priv->ndev->ifindex; skcb =3D j1939_skb_to_cb(skb); memcpy(skcb, rel_skcb, sizeof(*skcb)); =20 session =3D j1939_session_new(priv, skb, size); diff --git a/net/can/raw.c b/net/can/raw.c index 022154b0f6cc..eee244ffc31e 100644 --- a/net/can/raw.c +++ b/net/can/raw.c @@ -951,23 +951,22 @@ static int raw_sendmsg(struct socket *sock, struct ms= ghdr *msg, size_t size) if (can_cap_enabled(dev, CAN_CAP_RO)) { err =3D -EACCES; goto put_dev; } =20 - skb =3D sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv), - msg->msg_flags & MSG_DONTWAIT, &err); + skb =3D sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT, + &err); if (!skb) goto put_dev; =20 csx =3D can_skb_ext_add(skb); if (!csx) { kfree_skb(skb); err =3D -ENOMEM; goto put_dev; } =20 - can_skb_reserve(skb); csx->can_iif =3D dev->ifindex; =20 /* fill the skb before testing for valid CAN frames */ err =3D memcpy_from_msg(skb_put(skb, size), msg, size); if (err < 0) --=20 2.51.0