[PATCH net-next 0/7] pull-request: can-next 2025-06-10

[PATCH net-next 0/7] pull-request: can-next 2025-06-10

[Marc Kleine-Budde]

Hello netdev-team,

this is a pull request of 7 patches for net-next/main.

The first 4 patches are by Vincent Mailhol and prepare the CAN netlink
interface for the introduction of CAN XL configuration.

Geert Uytterhoeven's patch updates the CAN networking documentation.

The last 2 patched are by Davide Caratti and introduce skb drop
reasons in the receive path of several CAN protocols.

regards,
Marc

---

The following changes since commit 2c7e4a2663a1ab5a740c59c31991579b6b865a26:

  Merge tag 'net-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net (2025-06-05 12:34:55 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git tags/linux-can-next-for-6.17-20250610

for you to fetch changes up to af42404179c0e7b590ddfe56c4a753ace39cc1a4:

  Merge patch series "can: add drop reasons in the receive path" (2025-06-10 11:44:18 +0200)

----------------------------------------------------------------
linux-can-next-for-6.17-20250610

----------------------------------------------------------------
Davide Caratti (2):
      can: add drop reasons in the receive path of AF_CAN
      can: add drop reasons in CAN protocols receive path

Geert Uytterhoeven (1):
      documentation: networking: can: Document alloc_candev_mqs()

Marc Kleine-Budde (2):
      Merge patch series "can: netlink: preparation before introduction of CAN XL"
      Merge patch series "can: add drop reasons in the receive path"

Vincent Mailhol (4):
      can: netlink: replace tabulation by space in assignment
      can: bittiming: rename CAN_CTRLMODE_TDC_MASK into CAN_CTRLMODE_FD_TDC_MASK
      can: bittiming: rename can_tdc_is_enabled() into can_fd_tdc_is_enabled()
      can: netlink: can_changelink(): rename tdc_mask into fd_tdc_flag_provided

 Documentation/networking/can.rst          | 11 ++++-------
 drivers/net/can/dev/calc_bittiming.c      |  2 +-
 drivers/net/can/dev/netlink.c             | 26 +++++++++++++-------------
 drivers/net/can/usb/etas_es58x/es58x_fd.c |  2 +-
 drivers/net/can/xilinx_can.c              |  2 +-
 include/linux/can/bittiming.h             |  2 +-
 include/linux/can/dev.h                   |  4 ++--
 include/net/dropreason-core.h             | 18 ++++++++++++++++++
 net/can/af_can.c                          |  6 +++---
 net/can/bcm.c                             |  5 +++--
 net/can/isotp.c                           |  5 +++--
 net/can/j1939/socket.c                    |  5 +++--
 net/can/raw.c                             |  5 +++--
 13 files changed, 56 insertions(+), 37 deletions(-)

[PATCH net-next 1/7] can: netlink: replace tabulation by space in assignment

[Marc Kleine-Budde]

From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

commit cfd98c838cbe ("can: netlink: move '=' operators back to
previous line (checkpatch fix)") inadvertently introduced a tabulation
between the IFLA_CAN_DATA_BITTIMING_CONST array index and the equal
sign.

Remove it.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://patch.msgid.link/20241112165118.586613-9-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index a36842ace084..4ebd5181aea9 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -18,7 +18,7 @@ static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
 	[IFLA_CAN_CLOCK] = { .len = sizeof(struct can_clock) },
 	[IFLA_CAN_BERR_COUNTER] = { .len = sizeof(struct can_berr_counter) },
 	[IFLA_CAN_DATA_BITTIMING] = { .len = sizeof(struct can_bittiming) },
-	[IFLA_CAN_DATA_BITTIMING_CONST]	= { .len = sizeof(struct can_bittiming_const) },
+	[IFLA_CAN_DATA_BITTIMING_CONST] = { .len = sizeof(struct can_bittiming_const) },
 	[IFLA_CAN_TERMINATION] = { .type = NLA_U16 },
 	[IFLA_CAN_TDC] = { .type = NLA_NESTED },
 	[IFLA_CAN_CTRLMODE_EXT] = { .type = NLA_NESTED },

base-commit: 2c7e4a2663a1ab5a740c59c31991579b6b865a26
-- 
2.47.2

Re: [PATCH net-next 1/7] can: netlink: replace tabulation by space in assignment

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Marc Kleine-Budde <mkl@pengutronix.de>:

On Tue, 10 Jun 2025 11:46:16 +0200 you wrote:
> From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> 
> commit cfd98c838cbe ("can: netlink: move '=' operators back to
> previous line (checkpatch fix)") inadvertently introduced a tabulation
> between the IFLA_CAN_DATA_BITTIMING_CONST array index and the equal
> sign.
> 
> [...]

Here is the summary with links:
  - [net-next,1/7] can: netlink: replace tabulation by space in assignment
    https://git.kernel.org/netdev/net-next/c/d08ad6c8613b
  - [net-next,2/7] can: bittiming: rename CAN_CTRLMODE_TDC_MASK into CAN_CTRLMODE_FD_TDC_MASK
    https://git.kernel.org/netdev/net-next/c/bee7e3322a28
  - [net-next,3/7] can: bittiming: rename can_tdc_is_enabled() into can_fd_tdc_is_enabled()
    https://git.kernel.org/netdev/net-next/c/23c0dc95bfa8
  - [net-next,4/7] can: netlink: can_changelink(): rename tdc_mask into fd_tdc_flag_provided
    https://git.kernel.org/netdev/net-next/c/527b99f44def
  - [net-next,5/7] documentation: networking: can: Document alloc_candev_mqs()
    (no matching commit)
  - [net-next,6/7] can: add drop reasons in the receive path of AF_CAN
    https://git.kernel.org/netdev/net-next/c/127c49624a09
  - [net-next,7/7] can: add drop reasons in CAN protocols receive path
    https://git.kernel.org/netdev/net-next/c/81807451c2a6

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

[PATCH net-next 2/7] can: bittiming: rename CAN_CTRLMODE_TDC_MASK into CAN_CTRLMODE_FD_TDC_MASK

[Marc Kleine-Budde]

From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

With the introduction of CAN XL, a new CAN_CTRLMODE_XL_TDC_MASK will
be introduced later on. Because CAN_CTRLMODE_TDC_MASK is not part of
the uapi, rename it to CAN_CTRLMODE_FD_TDC_MASK to make it more
explicit that this mask is meant for CAN FD.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://patch.msgid.link/20241112165118.586613-10-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/calc_bittiming.c |  2 +-
 drivers/net/can/dev/netlink.c        | 12 ++++++------
 include/linux/can/bittiming.h        |  2 +-
 include/linux/can/dev.h              |  2 +-
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/net/can/dev/calc_bittiming.c b/drivers/net/can/dev/calc_bittiming.c
index 3809c148fb88..a94bd67c670c 100644
--- a/drivers/net/can/dev/calc_bittiming.c
+++ b/drivers/net/can/dev/calc_bittiming.c
@@ -179,7 +179,7 @@ void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 	if (!tdc_const || !(ctrlmode_supported & CAN_CTRLMODE_TDC_AUTO))
 		return;
 
-	*ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
+	*ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
 
 	/* As specified in ISO 11898-1 section 11.3.3 "Transmitter
 	 * delay compensation" (TDC) is only applicable if data BRP is
diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 4ebd5181aea9..08261cfcf6b2 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -67,12 +67,12 @@ static int can_validate(struct nlattr *tb[], struct nlattr *data[],
 
 	if (data[IFLA_CAN_CTRLMODE]) {
 		struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);
-		u32 tdc_flags = cm->flags & CAN_CTRLMODE_TDC_MASK;
+		u32 tdc_flags = cm->flags & CAN_CTRLMODE_FD_TDC_MASK;
 
 		is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
 
 		/* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually exclusive */
-		if (tdc_flags == CAN_CTRLMODE_TDC_MASK)
+		if (tdc_flags == CAN_CTRLMODE_FD_TDC_MASK)
 			return -EOPNOTSUPP;
 		/* If one of the CAN_CTRLMODE_TDC_* flag is set then
 		 * TDC must be set and vice-versa
@@ -230,16 +230,16 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 			dev->mtu = CAN_MTU;
 			memset(&priv->fd.data_bittiming, 0,
 			       sizeof(priv->fd.data_bittiming));
-			priv->ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
+			priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
 			memset(&priv->fd.tdc, 0, sizeof(priv->fd.tdc));
 		}
 
-		tdc_mask = cm->mask & CAN_CTRLMODE_TDC_MASK;
+		tdc_mask = cm->mask & CAN_CTRLMODE_FD_TDC_MASK;
 		/* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually
 		 * exclusive: make sure to turn the other one off
 		 */
 		if (tdc_mask)
-			priv->ctrlmode &= cm->flags | ~CAN_CTRLMODE_TDC_MASK;
+			priv->ctrlmode &= cm->flags | ~CAN_CTRLMODE_FD_TDC_MASK;
 	}
 
 	if (data[IFLA_CAN_BITTIMING]) {
@@ -339,7 +339,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 			err = can_tdc_changelink(priv, data[IFLA_CAN_TDC],
 						 extack);
 			if (err) {
-				priv->ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
+				priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
 				return err;
 			}
 		} else if (!tdc_mask) {
diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h
index 9b8a9c39614b..5dfdbb63b1d5 100644
--- a/include/linux/can/bittiming.h
+++ b/include/linux/can/bittiming.h
@@ -14,7 +14,7 @@
 #define CAN_BITRATE_UNSET 0
 #define CAN_BITRATE_UNKNOWN (-1U)
 
-#define CAN_CTRLMODE_TDC_MASK					\
+#define CAN_CTRLMODE_FD_TDC_MASK				\
 	(CAN_CTRLMODE_TDC_AUTO | CAN_CTRLMODE_TDC_MANUAL)
 
 /*
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 492d23bec7be..e492dfa8a472 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -93,7 +93,7 @@ struct can_priv {
 
 static inline bool can_tdc_is_enabled(const struct can_priv *priv)
 {
-	return !!(priv->ctrlmode & CAN_CTRLMODE_TDC_MASK);
+	return !!(priv->ctrlmode & CAN_CTRLMODE_FD_TDC_MASK);
 }
 
 /*
-- 
2.47.2

[PATCH net-next 3/7] can: bittiming: rename can_tdc_is_enabled() into can_fd_tdc_is_enabled()

[Marc Kleine-Budde]

From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

With the introduction of CAN XL, a new can_xl_tdc_is_enabled() helper
function will be introduced later on. Rename can_tdc_is_enabled() into
can_fd_tdc_is_enabled() to make it more explicit that this helper is
meant for CAN FD.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://patch.msgid.link/20241112165118.586613-11-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/netlink.c             | 6 +++---
 drivers/net/can/usb/etas_es58x/es58x_fd.c | 2 +-
 drivers/net/can/xilinx_can.c              | 2 +-
 include/linux/can/dev.h                   | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 08261cfcf6b2..16b0f326c143 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -144,7 +144,7 @@ static int can_tdc_changelink(struct can_priv *priv, const struct nlattr *nla,
 	const struct can_tdc_const *tdc_const = priv->fd.tdc_const;
 	int err;
 
-	if (!tdc_const || !can_tdc_is_enabled(priv))
+	if (!tdc_const || !can_fd_tdc_is_enabled(priv))
 		return -EOPNOTSUPP;
 
 	err = nla_parse_nested(tb_tdc, IFLA_CAN_TDC_MAX, nla,
@@ -409,7 +409,7 @@ static size_t can_tdc_get_size(const struct net_device *dev)
 		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCF_MAX */
 	}
 
-	if (can_tdc_is_enabled(priv)) {
+	if (can_fd_tdc_is_enabled(priv)) {
 		if (priv->ctrlmode & CAN_CTRLMODE_TDC_MANUAL ||
 		    priv->fd.do_get_auto_tdcv)
 			size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCV */
@@ -490,7 +490,7 @@ static int can_tdc_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	     nla_put_u32(skb, IFLA_CAN_TDC_TDCF_MAX, tdc_const->tdcf_max)))
 		goto err_cancel;
 
-	if (can_tdc_is_enabled(priv)) {
+	if (can_fd_tdc_is_enabled(priv)) {
 		u32 tdcv;
 		int err = -EINVAL;
 
diff --git a/drivers/net/can/usb/etas_es58x/es58x_fd.c b/drivers/net/can/usb/etas_es58x/es58x_fd.c
index d924b053677b..6476add1c105 100644
--- a/drivers/net/can/usb/etas_es58x/es58x_fd.c
+++ b/drivers/net/can/usb/etas_es58x/es58x_fd.c
@@ -429,7 +429,7 @@ static int es58x_fd_enable_channel(struct es58x_priv *priv)
 		es58x_fd_convert_bittiming(&tx_conf_msg.data_bittiming,
 					   &priv->can.fd.data_bittiming);
 
-		if (can_tdc_is_enabled(&priv->can)) {
+		if (can_fd_tdc_is_enabled(&priv->can)) {
 			tx_conf_msg.tdc_enabled = 1;
 			tx_conf_msg.tdco = cpu_to_le16(priv->can.fd.tdc.tdco);
 			tx_conf_msg.tdcf = cpu_to_le16(priv->can.fd.tdc.tdcf);
diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index 3f2e378199ab..81baec8eb1e5 100644
--- a/drivers/net/can/xilinx_can.c
+++ b/drivers/net/can/xilinx_can.c
@@ -515,7 +515,7 @@ static int xcan_set_bittiming(struct net_device *ndev)
 	    priv->devtype.cantype == XAXI_CANFD_2_0) {
 		/* Setting Baud Rate prescaler value in F_BRPR Register */
 		btr0 = dbt->brp - 1;
-		if (can_tdc_is_enabled(&priv->can)) {
+		if (can_fd_tdc_is_enabled(&priv->can)) {
 			if (priv->devtype.cantype == XAXI_CANFD)
 				btr0 |= FIELD_PREP(XCAN_BRPR_TDCO_MASK, priv->can.fd.tdc.tdco) |
 					XCAN_BRPR_TDC_ENABLE;
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index e492dfa8a472..9a92cbe5b2cb 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -91,7 +91,7 @@ struct can_priv {
 				   struct can_berr_counter *bec);
 };
 
-static inline bool can_tdc_is_enabled(const struct can_priv *priv)
+static inline bool can_fd_tdc_is_enabled(const struct can_priv *priv)
 {
 	return !!(priv->ctrlmode & CAN_CTRLMODE_FD_TDC_MASK);
 }
-- 
2.47.2

[PATCH net-next 4/7] can: netlink: can_changelink(): rename tdc_mask into fd_tdc_flag_provided

[Marc Kleine-Budde]

From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

The only purpose of the tdc_mask variable is to check whether or not
any tdc flags (CAN_CTRLMODE_TDC_{AUTO,MANUAL}) were provided. At this
point, the actual value of the flags do no matter any more because
these can be deduced from some other information.

Rename the tdc_mask variable into fd_tdc_flag_provided to make this
more explicit. Note that the fd_ prefix is added in preparation of the
introduction of CAN XL.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://patch.msgid.link/20241112165118.586613-12-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/netlink.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 16b0f326c143..13826e8a707b 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -189,7 +189,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 			  struct netlink_ext_ack *extack)
 {
 	struct can_priv *priv = netdev_priv(dev);
-	u32 tdc_mask = 0;
+	bool fd_tdc_flag_provided = false;
 	int err;
 
 	/* We need synchronization with dev->stop() */
@@ -234,11 +234,11 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 			memset(&priv->fd.tdc, 0, sizeof(priv->fd.tdc));
 		}
 
-		tdc_mask = cm->mask & CAN_CTRLMODE_FD_TDC_MASK;
+		fd_tdc_flag_provided = cm->mask & CAN_CTRLMODE_FD_TDC_MASK;
 		/* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually
 		 * exclusive: make sure to turn the other one off
 		 */
-		if (tdc_mask)
+		if (fd_tdc_flag_provided)
 			priv->ctrlmode &= cm->flags | ~CAN_CTRLMODE_FD_TDC_MASK;
 	}
 
@@ -342,7 +342,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 				priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
 				return err;
 			}
-		} else if (!tdc_mask) {
+		} else if (!fd_tdc_flag_provided) {
 			/* Neither of TDC parameters nor TDC flags are
 			 * provided: do calculation
 			 */
-- 
2.47.2

[PATCH net-next 5/7] documentation: networking: can: Document alloc_candev_mqs()

[Marc Kleine-Budde]

From: Geert Uytterhoeven <geert+renesas@glider.be>

Since the introduction of alloc_candev_mqs() and friends, there is no
longer a need to allocate a generic network device and perform explicit
CAN-specific setup.  Remove the code showing this setup, and document
alloc_candev_mqs() instead.

Fixes: 39549eef3587f1c1 ("can: CAN Network device driver and Netlink interface")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/c0f9a706ba31f1a49eb72e58526cd294d97a1ce9.1748865431.git.geert+renesas@glider.be
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 Documentation/networking/can.rst | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/Documentation/networking/can.rst b/Documentation/networking/can.rst
index b018ce346392..bc1b585355f7 100644
--- a/Documentation/networking/can.rst
+++ b/Documentation/networking/can.rst
@@ -1104,15 +1104,12 @@ for writing CAN network device driver are described below:
 General Settings
 ----------------
 
+CAN network device drivers can use alloc_candev_mqs() and friends instead of
+alloc_netdev_mqs(), to automatically take care of CAN-specific setup:
+
 .. code-block:: C
 
-    dev->type  = ARPHRD_CAN; /* the netdevice hardware type */
-    dev->flags = IFF_NOARP;  /* CAN has no arp */
-
-    dev->mtu = CAN_MTU; /* sizeof(struct can_frame) -> Classical CAN interface */
-
-    or alternative, when the controller supports CAN with flexible data rate:
-    dev->mtu = CANFD_MTU; /* sizeof(struct canfd_frame) -> CAN FD interface */
+    dev = alloc_candev_mqs(...);
 
 The struct can_frame or struct canfd_frame is the payload of each socket
 buffer (skbuff) in the protocol family PF_CAN.
-- 
2.47.2

[PATCH net-next 6/7] can: add drop reasons in the receive path of AF_CAN

[Marc Kleine-Budde]

From: Davide Caratti <dcaratti@redhat.com>

Besides the existing pr_warn_once(), use skb drop reasons in case AF_CAN
layer drops non-conformant CAN{,FD,XL} frames, or conformant frames
received by "wrong" devices, so that it's possible to debug (and count)
such events using existing tracepoints:

| # perf record -e skb:kfree_skb -aR -- ./drv/canfdtest -v -g -l 1 vcan0
| # perf script
| [...]
| canfdtest  1123 [000]  3893.271264: skb:kfree_skb: skbaddr=0xffff975703c9f700 rx_sk=(nil) protocol=12 location=can_rcv+0x4b  reason: CAN_RX_INVALID_FRAME

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://patch.msgid.link/20250604160605.1005704-2-dcaratti@redhat.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 include/net/dropreason-core.h | 18 ++++++++++++++++++
 net/can/af_can.c              |  6 +++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index bcf9d7467e1a..b9e78290269e 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -121,6 +121,9 @@
 	FN(ARP_PVLAN_DISABLE)		\
 	FN(MAC_IEEE_MAC_CONTROL)	\
 	FN(BRIDGE_INGRESS_STP_STATE)	\
+	FN(CAN_RX_INVALID_FRAME)	\
+	FN(CANFD_RX_INVALID_FRAME)	\
+	FN(CANXL_RX_INVALID_FRAME)	\
 	FNe(MAX)
 
 /**
@@ -573,6 +576,21 @@ enum skb_drop_reason {
 	 * ingress bridge port does not allow frames to be forwarded.
 	 */
 	SKB_DROP_REASON_BRIDGE_INGRESS_STP_STATE,
+	/**
+	 * @SKB_DROP_REASON_CAN_RX_INVALID_FRAME: received
+	 * non conform CAN frame (or device is unable to receive CAN frames)
+	 */
+	SKB_DROP_REASON_CAN_RX_INVALID_FRAME,
+	/**
+	 * @SKB_DROP_REASON_CANFD_RX_INVALID_FRAME: received
+	 * non conform CAN-FD frame (or device is unable to receive CAN frames)
+	 */
+	SKB_DROP_REASON_CANFD_RX_INVALID_FRAME,
+	/**
+	 * @SKB_DROP_REASON_CANXL_RX_INVALID_FRAME: received
+	 * non conform CAN-XL frame (or device is unable to receive CAN frames)
+	 */
+	SKB_DROP_REASON_CANXL_RX_INVALID_FRAME,
 	/**
 	 * @SKB_DROP_REASON_MAX: the maximum of core drop reasons, which
 	 * shouldn't be used as a real 'reason' - only for tracing code gen
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 4aab7033c933..b2387a46794a 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -683,7 +683,7 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
-		kfree_skb(skb);
+		kfree_skb_reason(skb, SKB_DROP_REASON_CAN_RX_INVALID_FRAME);
 		return NET_RX_DROP;
 	}
 
@@ -698,7 +698,7 @@ static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
-		kfree_skb(skb);
+		kfree_skb_reason(skb, SKB_DROP_REASON_CANFD_RX_INVALID_FRAME);
 		return NET_RX_DROP;
 	}
 
@@ -713,7 +713,7 @@ static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
 		pr_warn_once("PF_CAN: dropped non conform CAN XL skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
-		kfree_skb(skb);
+		kfree_skb_reason(skb, SKB_DROP_REASON_CANXL_RX_INVALID_FRAME);
 		return NET_RX_DROP;
 	}
 
-- 
2.47.2

Re: [PATCH net-next 6/7] can: add drop reasons in the receive path of AF_CAN

[Jakub Kicinski]

On Tue, 10 Jun 2025 11:46:21 +0200 Marc Kleine-Budde wrote:
> Besides the existing pr_warn_once(), use skb drop reasons in case AF_CAN
> layer drops non-conformant CAN{,FD,XL} frames, or conformant frames
> received by "wrong" devices, so that it's possible to debug (and count)
> such events using existing tracepoints:

Hm, I wonder if the protocol is really the most useful way 
to categorize. Does it actually help to identify problems on
production systems?

AFAIU we try to categorize by drop condition. So given the condition
is:

	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canfd_skb(skb))) 

my intuition would be to split this into two: "not a CAN device" and
"invalid CAN frame". The latter not split by proto - user can dig into
the stack traces of the relevant drop for more details.

But drop reasons are not uAPI so we can re-align later.

Re: [PATCH net-next 6/7] can: add drop reasons in the receive path of AF_CAN

[Davide Caratti]

On Tue, Jun 10, 2025 at 03:50:39PM -0700, Jakub Kicinski wrote:
> On Tue, 10 Jun 2025 11:46:21 +0200 Marc Kleine-Budde wrote:
> > Besides the existing pr_warn_once(), use skb drop reasons in case AF_CAN
> > layer drops non-conformant CAN{,FD,XL} frames, or conformant frames
> > received by "wrong" devices, so that it's possible to debug (and count)
> > such events using existing tracepoints:
> 
> Hm, I wonder if the protocol is really the most useful way 
> to categorize. Does it actually help to identify problems on
> production systems?
> 
> AFAIU we try to categorize by drop condition. So given the condition
> is:
> 
> 	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canfd_skb(skb))) 
> 
> my intuition would be to split this into two: "not a CAN device" and
> "invalid CAN frame". 

hello,

yes, that makes sense: I will post a follow-up patch soon.

thanks,
-- 
davide

[PATCH net-next 7/7] can: add drop reasons in CAN protocols receive path

[Marc Kleine-Budde]

From: Davide Caratti <dcaratti@redhat.com>

sock_queue_rcv_skb() can fail because of lack of memory resources: use
drop reasons and pass the receiving socket to the tracepoint, so that
it's possible to better locate/debug such events.

Tested with:

| # modprobe vcan echo=1
| # ip link add name vcan2 type vcan
| # ip link set dev vcan2 up
| # ./netlayer/tst-proc 1 &
| # bg
| # while true ; do perf record -e skb:kfree_skb -aR  -- \
| > ./raw/tst-raw-sendto vcan2 ; perf script ; done
| [...]
| tst-raw-sendto 10942 [000] 506428.431856: skb:kfree_skb: skbaddr=0xffff97cec38b4200 rx_sk=0xffff97cf0f75a800 protocol=12 location=raw_rcv+0x20e reason: SOCKET_RCVBUF

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://patch.msgid.link/20250604160605.1005704-3-dcaratti@redhat.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/bcm.c          | 5 +++--
 net/can/isotp.c        | 5 +++--
 net/can/j1939/socket.c | 5 +++--
 net/can/raw.c          | 5 +++--
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 6bc1cc4c94c5..5e690a2377e4 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -359,6 +359,7 @@ static void bcm_send_to_user(struct bcm_op *op, struct bcm_msg_head *head,
 	unsigned int datalen = head->nframes * op->cfsiz;
 	int err;
 	unsigned int *pflags;
+	enum skb_drop_reason reason;
 
 	skb = alloc_skb(sizeof(*head) + datalen, gfp_any());
 	if (!skb)
@@ -413,11 +414,11 @@ static void bcm_send_to_user(struct bcm_op *op, struct bcm_msg_head *head,
 	addr->can_family  = AF_CAN;
 	addr->can_ifindex = op->rx_ifindex;
 
-	err = sock_queue_rcv_skb(sk, skb);
+	err = sock_queue_rcv_skb_reason(sk, skb, &reason);
 	if (err < 0) {
 		struct bcm_sock *bo = bcm_sk(sk);
 
-		kfree_skb(skb);
+		sk_skb_reason_drop(sk, skb, reason);
 		/* don't care about overflows in this statistic */
 		bo->dropped_usr_msgs++;
 	}
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 1efa377f002e..dee1412b3c9c 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -278,6 +278,7 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 flowstatus)
 static void isotp_rcv_skb(struct sk_buff *skb, struct sock *sk)
 {
 	struct sockaddr_can *addr = (struct sockaddr_can *)skb->cb;
+	enum skb_drop_reason reason;
 
 	BUILD_BUG_ON(sizeof(skb->cb) < sizeof(struct sockaddr_can));
 
@@ -285,8 +286,8 @@ static void isotp_rcv_skb(struct sk_buff *skb, struct sock *sk)
 	addr->can_family = AF_CAN;
 	addr->can_ifindex = skb->dev->ifindex;
 
-	if (sock_queue_rcv_skb(sk, skb) < 0)
-		kfree_skb(skb);
+	if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0)
+		sk_skb_reason_drop(sk, skb, reason);
 }
 
 static u8 padlen(u8 datalen)
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 6fefe7a68761..3d8b588822f9 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -311,6 +311,7 @@ static void j1939_sk_recv_one(struct j1939_sock *jsk, struct sk_buff *oskb)
 {
 	const struct j1939_sk_buff_cb *oskcb = j1939_skb_to_cb(oskb);
 	struct j1939_sk_buff_cb *skcb;
+	enum skb_drop_reason reason;
 	struct sk_buff *skb;
 
 	if (oskb->sk == &jsk->sk)
@@ -331,8 +332,8 @@ static void j1939_sk_recv_one(struct j1939_sock *jsk, struct sk_buff *oskb)
 	if (skb->sk)
 		skcb->msg_flags |= MSG_DONTROUTE;
 
-	if (sock_queue_rcv_skb(&jsk->sk, skb) < 0)
-		kfree_skb(skb);
+	if (sock_queue_rcv_skb_reason(&jsk->sk, skb, &reason) < 0)
+		sk_skb_reason_drop(&jsk->sk, skb, reason);
 }
 
 bool j1939_sk_recv_match(struct j1939_priv *priv, struct j1939_sk_buff_cb *skcb)
diff --git a/net/can/raw.c b/net/can/raw.c
index 020f21430b1d..76b867d21def 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -129,6 +129,7 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 {
 	struct sock *sk = (struct sock *)data;
 	struct raw_sock *ro = raw_sk(sk);
+	enum skb_drop_reason reason;
 	struct sockaddr_can *addr;
 	struct sk_buff *skb;
 	unsigned int *pflags;
@@ -205,8 +206,8 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	if (oskb->sk == sk)
 		*pflags |= MSG_CONFIRM;
 
-	if (sock_queue_rcv_skb(sk, skb) < 0)
-		kfree_skb(skb);
+	if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0)
+		sk_skb_reason_drop(sk, skb, reason);
 }
 
 static int raw_enable_filters(struct net *net, struct net_device *dev,
-- 
2.47.2