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Message-ID: <20260125201601.5018-6-socketcan@hartkopp.net>
Date: Sun, 25 Jan 2026 21:16:00 +0100
From: Oliver Hartkopp <socketcan@...tkopp.net>
To: netdev@...r.kernel.org,
linux-can@...r.kernel.org
Cc: Oliver Hartkopp <socketcan@...tkopp.net>
Subject: [net-next 5/6] can: remove private CAN skb headroom infrastructure
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.
Patch 5/6 to remove the private CAN bus skb headroom infrastructure.
Signed-off-by: Oliver Hartkopp <socketcan@...tkopp.net>
---
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 | 4 +---
7 files changed, 19 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, unsigned int idx,
}
}
EXPORT_SYMBOL_GPL(can_free_echo_skb);
/* 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 = PACKET_BROADCAST;
skb->ip_summed = CHECKSUM_UNNECESSARY;
-
- skb_reset_mac_header(skb);
- skb_reset_network_header(skb);
- skb_reset_transport_header(skb);
-
- can_skb_reserve(skb);
}
struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
{
struct sk_buff *skb;
struct can_skb_ext *csx;
- skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
- sizeof(struct can_frame));
+ skb = netdev_alloc_skb(dev, sizeof(struct can_frame));
if (unlikely(!skb))
goto out_error_cc;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
goto out_error_cc;
}
skb->protocol = htons(ETH_P_CAN);
- init_can_skb_reserve(skb);
+ init_can_skb(skb);
csx->can_iif = dev->ifindex;
*cf = skb_put_zero(skb, sizeof(struct can_frame));
return skb;
@@ -253,23 +246,22 @@ struct sk_buff *alloc_canfd_skb(struct net_device *dev,
struct canfd_frame **cfd)
{
struct sk_buff *skb;
struct can_skb_ext *csx;
- skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
- sizeof(struct canfd_frame));
+ skb = netdev_alloc_skb(dev, sizeof(struct canfd_frame));
if (unlikely(!skb))
goto out_error_fd;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
goto out_error_fd;
}
skb->protocol = htons(ETH_P_CANFD);
- init_can_skb_reserve(skb);
+ init_can_skb(skb);
csx->can_iif = dev->ifindex;
*cfd = skb_put_zero(skb, sizeof(struct canfd_frame));
/* set CAN FD flag by default */
@@ -292,23 +284,22 @@ struct sk_buff *alloc_canxl_skb(struct net_device *dev,
struct can_skb_ext *csx;
if (data_len < CANXL_MIN_DLEN || data_len > CANXL_MAX_DLEN)
goto out_error_xl;
- skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
- CANXL_HDR_SIZE + data_len);
+ skb = netdev_alloc_skb(dev, CANXL_HDR_SIZE + data_len);
if (unlikely(!skb))
goto out_error_xl;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
goto out_error_xl;
}
skb->protocol = htons(ETH_P_CANXL);
- init_can_skb_reserve(skb);
+ init_can_skb(skb);
csx->can_iif = dev->ifindex;
*cxl = skb_put_zero(skb, CANXL_HDR_SIZE + data_len);
/* 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);
/* 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 = can_skb_ext_find(skb);
- /* 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 == CHECKSUM_NONE || !csx) {
/* init CAN skb content */
if (!csx) {
csx = can_skb_ext_add(skb);
@@ -403,11 +390,11 @@ bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb)
default:
goto inval_skb;
}
- if (!can_skb_headroom_valid(dev, skb))
+ if (!can_skb_init_valid(dev, skb))
goto inval_skb;
return false;
inval_skb:
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index aeb08f47de48..cacbbb185bb9 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);
-/*
- * The struct can_skb_priv is used to transport additional information along
- * with the stored struct can(fd)_frame that can not be contained in existing
- * 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)
{
return skb_ext_add(skb, SKB_EXT_CAN);
}
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;
}
- skb = alloc_skb(op->cfsiz + sizeof(struct can_skb_priv), gfp_any());
+ skb = alloc_skb(op->cfsiz, gfp_any());
if (!skb)
goto out;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
goto out;
}
- can_skb_reserve(skb);
csx->can_iif = dev->ifindex;
skb_put_data(skb, cf, op->cfsiz);
/* send with loopback */
@@ -1331,22 +1330,20 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk,
/* we need a real device to send frames */
if (!ifindex)
return -ENODEV;
- skb = alloc_skb(cfsiz + sizeof(struct can_skb_priv), GFP_KERNEL);
+ skb = alloc_skb(cfsiz, GFP_KERNEL);
if (!skb)
return -ENOMEM;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
return -ENOMEM;
}
- can_skb_reserve(skb);
-
err = 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 01ceb3febbb7..434986cc8fe5 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 = isotp_sk(sk);
int can_send_ret;
- nskb = alloc_skb(so->ll.mtu + sizeof(struct can_skb_priv), gfp_any());
+ nskb = alloc_skb(so->ll.mtu, gfp_any());
if (!nskb)
return 1;
csx = 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;
}
- can_skb_reserve(nskb);
csx->can_iif = dev->ifindex;
-
nskb->dev = dev;
can_skb_set_owner(nskb, sk);
ncf = (struct canfd_frame *)nskb->data;
skb_put_zero(nskb, so->ll.mtu);
@@ -778,11 +776,11 @@ static void isotp_send_cframe(struct isotp_sock *so)
dev = dev_get_by_index(sock_net(sk), so->ifindex);
if (!dev)
return;
- skb = alloc_skb(so->ll.mtu + sizeof(struct can_skb_priv), GFP_ATOMIC);
+ skb = alloc_skb(so->ll.mtu, GFP_ATOMIC);
if (!skb) {
dev_put(dev);
return;
}
@@ -791,11 +789,10 @@ static void isotp_send_cframe(struct isotp_sock *so)
kfree_skb(skb);
dev_put(dev);
return;
}
- can_skb_reserve(skb);
csx->can_iif = dev->ifindex;
cf = (struct canfd_frame *)skb->data;
skb_put_zero(skb, so->ll.mtu);
@@ -1013,12 +1010,12 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
if (!dev) {
err = -ENXIO;
goto err_out_drop;
}
- skb = sock_alloc_send_skb(sk, so->ll.mtu + sizeof(struct can_skb_priv),
- msg->msg_flags & MSG_DONTWAIT, &err);
+ skb = sock_alloc_send_skb(sk, so->ll.mtu, msg->msg_flags & MSG_DONTWAIT,
+ &err);
if (!skb) {
dev_put(dev);
goto err_out_drop;
}
@@ -1027,11 +1024,10 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
kfree_skb(skb);
dev_put(dev);
goto err_out_drop;
}
- can_skb_reserve(skb);
csx->can_iif = dev->ifindex;
so->tx.len = size;
so->tx.idx = 0;
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index f03bae79354e..10014d95c319 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -889,23 +889,21 @@ static struct sk_buff *j1939_sk_alloc_skb(struct net_device *ndev,
int ret;
skb = 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;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
goto failure;
}
- can_skb_reserve(skb);
csx->can_iif = ndev->ifindex;
skb_reserve(skb, offsetof(struct can_frame, data));
ret = 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 96e02ad4a726..e63cf79af1c4 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;
- skb = alloc_skb(sizeof(struct can_frame) + sizeof(struct can_skb_priv),
- GFP_ATOMIC);
+ skb = alloc_skb(sizeof(struct can_frame), GFP_ATOMIC);
if (unlikely(!skb))
return ERR_PTR(-ENOMEM);
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
return ERR_PTR(-ENOMEM);
}
skb->dev = priv->ndev;
- can_skb_reserve(skb);
csx->can_iif = priv->ndev->ifindex;
/* reserve CAN header */
skb_reserve(skb, offsetof(struct can_frame, data));
/* skb->cb must be large enough to hold a j1939_sk_buff_cb structure */
@@ -1535,22 +1533,21 @@ 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;
- skb = alloc_skb(size + sizeof(struct can_skb_priv), GFP_ATOMIC);
+ skb = alloc_skb(size, GFP_ATOMIC);
if (unlikely(!skb))
return NULL;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
return NULL;
}
skb->dev = priv->ndev;
- can_skb_reserve(skb);
csx->can_iif = priv->ndev->ifindex;
skcb = j1939_skb_to_cb(skb);
memcpy(skcb, rel_skcb, sizeof(*skcb));
session = j1939_session_new(priv, skb, size);
diff --git a/net/can/raw.c b/net/can/raw.c
index e26cda398e22..2b4a238d2590 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -951,22 +951,20 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
if (can_cap_enabled(dev, CAN_CAP_RO)) {
err = -EACCES;
goto put_dev;
}
- skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
- msg->msg_flags & MSG_DONTWAIT, &err);
+ skb = sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT, &err);
if (!skb)
goto put_dev;
csx = can_skb_ext_add(skb);
if (!csx) {
kfree_skb(skb);
goto put_dev;
}
- can_skb_reserve(skb);
csx->can_iif = dev->ifindex;
/* fill the skb before testing for valid CAN frames */
err = memcpy_from_msg(skb_put(skb, size), msg, size);
if (err < 0)
--
2.47.3
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