[PATCH can-next v2 1/6] can: use skb hash instead of private variable in headroom
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: 2026-01-28 09:29:30
Also in:
linux-can, lkml
Subsystem:
can network drivers, can network layer, can-j1939 network layer, the rest · Maintainers:
Marc Kleine-Budde, Vincent Mailhol, Oliver Hartkopp, Robin van der Gracht, Oleksij Rempel, Linus Torvalds
From: Oliver Hartkopp <socketcan@hartkopp.net> The can_skb_priv::skbcnt variable is used to identify CAN skbs in the RX path analogue to the skb->hash. As the skb hash is not filled in CAN skbs move the private skbcnt value to skb->hash and set skb->sw_hash accordingly. The skb->hash is a value used for RPS to identify skbs. Use it as intended. Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> --- drivers/net/can/dev/skb.c | 2 -- include/linux/can/core.h | 1 + include/linux/can/skb.h | 2 -- net/can/af_can.c | 14 +++++++++++--- net/can/bcm.c | 2 -- net/can/isotp.c | 3 --- net/can/j1939/socket.c | 1 - net/can/j1939/transport.c | 2 -- net/can/raw.c | 7 +++---- 9 files changed, 15 insertions(+), 19 deletions(-)
diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c
index 3ebd4f779b9b..0da615afa04d 100644
--- a/drivers/net/can/dev/skb.c
+++ b/drivers/net/can/dev/skb.c@@ -202,7 +202,6 @@ static void init_can_skb_reserve(struct sk_buff *skb) skb_reset_transport_header(skb); can_skb_reserve(skb); - can_skb_prv(skb)->skbcnt = 0; } struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
@@ -312,7 +311,6 @@ static bool can_skb_headroom_valid(struct net_device *dev, struct sk_buff *skb) if (skb->ip_summed == CHECKSUM_NONE) { /* init headroom */ can_skb_prv(skb)->ifindex = dev->ifindex; - can_skb_prv(skb)->skbcnt = 0; skb->ip_summed = CHECKSUM_UNNECESSARY;
diff --git a/include/linux/can/core.h b/include/linux/can/core.h
index 5fb8d0e3f9c1..5c382ed61755 100644
--- a/include/linux/can/core.h
+++ b/include/linux/can/core.h@@ -58,6 +58,7 @@ extern void can_rx_unregister(struct net *net, struct net_device *dev, void *data); extern int can_send(struct sk_buff *skb, int loop); +extern void can_set_skb_uid(struct sk_buff *skb); void can_sock_destruct(struct sock *sk); #endif /* !_CAN_CORE_H */
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index 1abc25a8d144..869ea574a40a 100644
--- a/include/linux/can/skb.h
+++ b/include/linux/can/skb.h@@ -49,13 +49,11 @@ bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb); /** * struct can_skb_priv - private additional data inside CAN sk_buffs * @ifindex: ifindex of the first interface the CAN frame appeared on - * @skbcnt: atomic counter to have an unique id together with skb pointer * @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; - int skbcnt; unsigned int frame_len; struct can_frame cf[]; };
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 770173d8db42..70659987ef4d 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c@@ -641,6 +641,16 @@ static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buf return matches; } +void can_set_skb_uid(struct sk_buff *skb) +{ + /* create non-zero unique skb identifier together with *skb */ + while (!(skb->hash)) + skb->hash = atomic_inc_return(&skbcounter); + + skb->sw_hash = 1; +} +EXPORT_SYMBOL(can_set_skb_uid); + static void can_receive(struct sk_buff *skb, struct net_device *dev) { struct can_dev_rcv_lists *dev_rcv_lists;
@@ -652,9 +662,7 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev) atomic_long_inc(&pkg_stats->rx_frames); atomic_long_inc(&pkg_stats->rx_frames_delta); - /* create non-zero unique skb identifier together with *skb */ - while (!(can_skb_prv(skb)->skbcnt)) - can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter); + can_set_skb_uid(skb); rcu_read_lock();
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 7eba8ae01a5b..8ed60f18c2ea 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c@@ -316,7 +316,6 @@ static void bcm_can_tx(struct bcm_op *op) can_skb_reserve(skb); can_skb_prv(skb)->ifindex = dev->ifindex; - can_skb_prv(skb)->skbcnt = 0; skb_put_data(skb, cf, op->cfsiz);
@@ -1344,7 +1343,6 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk, } can_skb_prv(skb)->ifindex = dev->ifindex; - can_skb_prv(skb)->skbcnt = 0; skb->dev = dev; can_skb_set_owner(skb, sk); err = can_send(skb, 1); /* send with loopback */
diff --git a/net/can/isotp.c b/net/can/isotp.c
index ce588b85665a..4bb60b8f9b96 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c@@ -230,7 +230,6 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 flowstatus) can_skb_reserve(nskb); can_skb_prv(nskb)->ifindex = dev->ifindex; - can_skb_prv(nskb)->skbcnt = 0; nskb->dev = dev; can_skb_set_owner(nskb, sk);
@@ -780,7 +779,6 @@ static void isotp_send_cframe(struct isotp_sock *so) can_skb_reserve(skb); can_skb_prv(skb)->ifindex = dev->ifindex; - can_skb_prv(skb)->skbcnt = 0; cf = (struct canfd_frame *)skb->data; skb_put_zero(skb, so->ll.mtu);
@@ -1009,7 +1007,6 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) can_skb_reserve(skb); can_skb_prv(skb)->ifindex = dev->ifindex; - can_skb_prv(skb)->skbcnt = 0; so->tx.len = size; so->tx.idx = 0;
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index ff9c4fd7b433..1589e8ca634e 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c@@ -897,7 +897,6 @@ static struct sk_buff *j1939_sk_alloc_skb(struct net_device *ndev, can_skb_reserve(skb); can_skb_prv(skb)->ifindex = ndev->ifindex; - can_skb_prv(skb)->skbcnt = 0; skb_reserve(skb, offsetof(struct can_frame, data)); ret = memcpy_from_msg(skb_put(skb, size), msg, size);
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 8656ab388c83..d5d3e5320f7a 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c@@ -601,7 +601,6 @@ sk_buff *j1939_tp_tx_dat_new(struct j1939_priv *priv, skb->dev = priv->ndev; can_skb_reserve(skb); can_skb_prv(skb)->ifindex = priv->ndev->ifindex; - can_skb_prv(skb)->skbcnt = 0; /* reserve CAN header */ skb_reserve(skb, offsetof(struct can_frame, data));
@@ -1536,7 +1535,6 @@ j1939_session *j1939_session_fresh_new(struct j1939_priv *priv, skb->dev = priv->ndev; can_skb_reserve(skb); can_skb_prv(skb)->ifindex = priv->ndev->ifindex; - can_skb_prv(skb)->skbcnt = 0; skcb = j1939_skb_to_cb(skb); memcpy(skcb, rel_skcb, sizeof(*skcb));
diff --git a/net/can/raw.c b/net/can/raw.c
index 12293363413c..fb4f9c854df0 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c@@ -76,7 +76,7 @@ MODULE_ALIAS("can-proto-1"); struct uniqframe { const struct sk_buff *skb; - int skbcnt; + u32 hash; unsigned int join_rx_count; };
@@ -164,7 +164,7 @@ static void raw_rcv(struct sk_buff *oskb, void *data) /* eliminate multiple filter matches for the same skb */ if (this_cpu_ptr(ro->uniq)->skb == oskb && - this_cpu_ptr(ro->uniq)->skbcnt == can_skb_prv(oskb)->skbcnt) { + this_cpu_ptr(ro->uniq)->hash == oskb->hash) { if (!ro->join_filters) return;
@@ -174,7 +174,7 @@ static void raw_rcv(struct sk_buff *oskb, void *data) return; } else { this_cpu_ptr(ro->uniq)->skb = oskb; - this_cpu_ptr(ro->uniq)->skbcnt = can_skb_prv(oskb)->skbcnt; + this_cpu_ptr(ro->uniq)->hash = oskb->hash; this_cpu_ptr(ro->uniq)->join_rx_count = 1; /* drop first frame to check all enabled filters? */ if (ro->join_filters && ro->count > 1)
@@ -958,7 +958,6 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) can_skb_reserve(skb); can_skb_prv(skb)->ifindex = dev->ifindex; - can_skb_prv(skb)->skbcnt = 0; /* fill the skb before testing for valid CAN frames */ err = memcpy_from_msg(skb_put(skb, size), msg, size);
--
2.51.0