Hello Kurt,
thanks for the patch.
I really appreciate this extension.
Some remarks inline ...
On 15.10.2010 17:38, Kurt Van Dijck wrote:
> diff --git a/Documentation/networking/can.txt
> b/Documentation/networking/can.txt
> index cd79735..95341aa 100644
> --- a/Documentation/networking/can.txt
> +++ b/Documentation/networking/can.txt
> @@ -22,6 +22,7 @@ This file contains
> 4.1.2 RAW socket option CAN_RAW_ERR_FILTER
> 4.1.3 RAW socket option CAN_RAW_LOOPBACK
> 4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
> + 4.1.5 RAW socket returned flags
> 4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
> 4.3 connected transport protocols (SOCK_SEQPACKET)
> 4.4 unconnected transport protocols (SOCK_DGRAM)
> @@ -471,6 +472,16 @@ solution for a couple of reasons:
> setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
> &recv_own_msgs, sizeof(recv_own_msgs));
>
> + 4.1.5 RAW socket returned flags
> +
> + When using recvmsg() call, the msg->msg_flags may contain following flags:
> +
> + MSG_DONTROUTE: set when the frame was sent via the same physical device,
> + ie. a loopback frame.
According the code MSG_DONTROUTE indicates frames that have been originated on
the local host. Nothing more.
Only when you enabled CAN_RAW_RECV_OWN_MSGS and you bound the socket to a
specific CAN interface, the description becomes correct.
Better write:
MSG_DONTROUTE : set when the received frame was created on the local host.
> + MSG_CONFIRM: set when the frame was sent via the socket it is received
> on.
ok.
> + This flag acts as a 'transmission confirmation'.
Better:
This flag can be interpreted as a 'transmission confirmation' when the CAN
driver supports the echo of CAN frames on driver level, see 3.2 and 6.2
> + In order to receive such messages, CAN_RAW_RECV_OWN_MSGS must be set.
> +
> 4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
> 4.3 connected transport protocols (SOCK_SEQPACKET)
> 4.4 unconnected transport protocols (SOCK_DGRAM)
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 7d77e67..9020c4f 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -90,23 +90,39 @@ struct raw_sock {
> can_err_mask_t err_mask;
> };
>
> +/*
> + * return some space to store extra msg flags in.
> + * We use 1 int beyond the 'struct sockaddr_can' in skb->cb
> + * to store those.
> + * These flags will be use in raw_recvmsg()
> + */
/*
* Return pointer to store the extra msg flags for raw_recvmsg().
* We use the space of one unsigned int beyond the 'struct sockaddr_can'
* in skb->cb.
*/
> +static inline unsigned int *raw_flags(struct sk_buff *skb)
> +{
> + BUILD_BUG_ON(sizeof(skb->cb) <= (sizeof(struct sockaddr_can)
> + + sizeof(unsigned int)));
One empty line would be nice here ...
> + /* return pointer after struct sockaddr_can */
> + return (unsigned int *)(&((struct sockaddr_can *)skb->cb)[1]);
> +}
> +
> static inline struct raw_sock *raw_sk(const struct sock *sk)
> {
> return (struct raw_sock *)sk;
> }
>
> -static void raw_rcv(struct sk_buff *skb, void *data)
> +static void raw_rcv(struct sk_buff *oskb, void *data)
> {
> struct sock *sk = (struct sock *)data;
> struct raw_sock *ro = raw_sk(sk);
> struct sockaddr_can *addr;
> + struct sk_buff *skb;
> + unsigned int *pflags;
>
> /* check the received tx sock reference */
> - if (!ro->recv_own_msgs && skb->sk == sk)
> + if (!ro->recv_own_msgs && oskb->sk == sk)
> return;
>
> /* clone the given skb to be able to enqueue it into the rcv queue */
> - skb = skb_clone(skb, GFP_ATOMIC);
> + skb = skb_clone(oskb, GFP_ATOMIC);
> if (!skb)
> return;
>
> @@ -123,6 +139,14 @@ static void raw_rcv(struct sk_buff *skb, void *data)
> addr->can_family = AF_CAN;
> addr->can_ifindex = skb->dev->ifindex;
>
> + /* prepare the flags for raw_recvmsg() */
> + pflags = raw_flags(skb);
> + *pflags = 0;
> + if (oskb->sk)
> + *pflags |= MSG_DONTROUTE;
> + if (oskb->sk == sk)
> + *pflags |= MSG_CONFIRM;
> +
A good improvement since your first proof-of-concept code :-)
> if (sock_queue_rcv_skb(sk, skb) < 0)
> kfree_skb(skb);
> }
> @@ -707,6 +731,9 @@ static int raw_recvmsg(struct kiocb *iocb, struct socket
> *sock,
> memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
> }
>
> + /* assign the flags that have been recorded in raw_rcv() */
> + msg->msg_flags |= *(raw_flags(skb));
> +
dito :-)
> skb_free_datagram(sk, skb);
>
> return size;
Tnx & regards,
Oliver
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