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cc4b08c31b
The actual payload length of the CAN Remote Transmission Request (RTR)
frames is always 0, i.e. no payload is transmitted on the wire.
However, those RTR frames still use the DLC to indicate the length of
the requested frame.
As such, net_device_stats::tx_bytes should not be increased when
sending RTR frames.
The function can_get_echo_skb() already returns the correct length,
even for RTR frames (c.f. [1]). However, for historical reasons, the
drivers do not use can_get_echo_skb()'s return value and instead, most
of them store a temporary length (or dlc) in some local structure or
array. Using the return value of can_get_echo_skb() solves the
issue. After doing this, such length/dlc fields become unused and so
this patch does the adequate cleaning when needed.
This patch fixes all the CAN drivers.
Finally, can_get_echo_skb() is decorated with the __must_check
attribute in order to force future drivers to correctly use its return
value (else the compiler would emit a warning).
[1] commit ed3320cec2 ("can: dev: __can_get_echo_skb():
fix real payload length return value for RTR frames")
Link: https://lore.kernel.org/all/20211207121531.42941-6-mailhol.vincent@wanadoo.fr
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Yasushi SHOJI <yashi@spacecubics.com>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Stephane Grosjean <s.grosjean@peak-system.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Tested-by: Jimmy Assarsson <extja@kvaser.com> # kvaser
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Acked-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2
Tested-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2
[mkl: add conversion for grcan]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
163 lines
4.5 KiB
C
163 lines
4.5 KiB
C
/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
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/*
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* linux/can/skb.h
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*
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* Definitions for the CAN network socket buffer
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*
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* Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
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*
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*/
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#ifndef _CAN_SKB_H
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#define _CAN_SKB_H
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#include <linux/types.h>
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#include <linux/skbuff.h>
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#include <linux/can.h>
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#include <net/sock.h>
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void can_flush_echo_skb(struct net_device *dev);
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int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
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unsigned int idx, unsigned int frame_len);
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struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
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u8 *len_ptr, unsigned int *frame_len_ptr);
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unsigned int __must_check can_get_echo_skb(struct net_device *dev,
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unsigned int idx,
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unsigned int *frame_len_ptr);
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void can_free_echo_skb(struct net_device *dev, unsigned int idx,
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unsigned int *frame_len_ptr);
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struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
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struct sk_buff *alloc_canfd_skb(struct net_device *dev,
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struct canfd_frame **cfd);
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struct sk_buff *alloc_can_err_skb(struct net_device *dev,
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struct can_frame **cf);
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/*
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* The struct can_skb_priv is used to transport additional information along
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* with the stored struct can(fd)_frame that can not be contained in existing
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* struct sk_buff elements.
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* N.B. that this information must not be modified in cloned CAN sk_buffs.
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* To modify the CAN frame content or the struct can_skb_priv content
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* skb_copy() needs to be used instead of skb_clone().
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*/
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/**
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* struct can_skb_priv - private additional data inside CAN sk_buffs
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* @ifindex: ifindex of the first interface the CAN frame appeared on
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* @skbcnt: atomic counter to have an unique id together with skb pointer
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* @frame_len: length of CAN frame in data link layer
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* @cf: align to the following CAN frame at skb->data
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*/
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struct can_skb_priv {
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int ifindex;
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int skbcnt;
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unsigned int frame_len;
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struct can_frame cf[];
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};
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static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
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{
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return (struct can_skb_priv *)(skb->head);
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}
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static inline void can_skb_reserve(struct sk_buff *skb)
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{
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skb_reserve(skb, sizeof(struct can_skb_priv));
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}
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static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
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{
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/* If the socket has already been closed by user space, the
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* refcount may already be 0 (and the socket will be freed
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* after the last TX skb has been freed). So only increase
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* socket refcount if the refcount is > 0.
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*/
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if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) {
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skb->destructor = sock_efree;
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skb->sk = sk;
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}
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}
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/*
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* returns an unshared skb owned by the original sock to be echo'ed back
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*/
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static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
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{
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struct sk_buff *nskb;
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nskb = skb_clone(skb, GFP_ATOMIC);
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if (unlikely(!nskb)) {
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kfree_skb(skb);
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return NULL;
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}
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can_skb_set_owner(nskb, skb->sk);
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consume_skb(skb);
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return nskb;
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}
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/* Check for outgoing skbs that have not been created by the CAN subsystem */
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static inline bool can_skb_headroom_valid(struct net_device *dev,
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struct sk_buff *skb)
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{
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/* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */
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if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv)))
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return false;
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/* af_packet does not apply CAN skb specific settings */
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if (skb->ip_summed == CHECKSUM_NONE) {
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/* init headroom */
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can_skb_prv(skb)->ifindex = dev->ifindex;
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can_skb_prv(skb)->skbcnt = 0;
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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/* perform proper loopback on capable devices */
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if (dev->flags & IFF_ECHO)
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skb->pkt_type = PACKET_LOOPBACK;
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else
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skb->pkt_type = PACKET_HOST;
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skb_reset_mac_header(skb);
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skb_reset_network_header(skb);
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skb_reset_transport_header(skb);
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}
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return true;
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}
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/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
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static inline bool can_dropped_invalid_skb(struct net_device *dev,
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struct sk_buff *skb)
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{
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const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
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if (skb->protocol == htons(ETH_P_CAN)) {
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if (unlikely(skb->len != CAN_MTU ||
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cfd->len > CAN_MAX_DLEN))
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goto inval_skb;
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} else if (skb->protocol == htons(ETH_P_CANFD)) {
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if (unlikely(skb->len != CANFD_MTU ||
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cfd->len > CANFD_MAX_DLEN))
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goto inval_skb;
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} else
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goto inval_skb;
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if (!can_skb_headroom_valid(dev, skb))
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goto inval_skb;
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return false;
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inval_skb:
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kfree_skb(skb);
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dev->stats.tx_dropped++;
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return true;
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}
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static inline bool can_is_canfd_skb(const struct sk_buff *skb)
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{
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/* the CAN specific type of skb is identified by its data length */
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return skb->len == CANFD_MTU;
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}
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#endif /* !_CAN_SKB_H */
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