On Fri, Nov 25, 2022 at 06:04:18PM +0100, Devid Antonio Filoni wrote:
> The ISO 11783-5 standard, in "4.5.2 - Address claim requirements", states:
> d) No CF shall begin, or resume, transmission on the network until 250
> ms after it has successfully claimed an address except when
> responding to a request for address-claimed.
>
> But "Figure 6" and "Figure 7" in "4.5.4.2 - Address-claim
> prioritization" show that the CF begins the transmission after 250 ms
> from the first AC (address-claimed) message even if it sends another AC
> message during that time window to resolve the address contention with
> another CF.
>
> As stated in "4.4.2.3 - Address-claimed message":
> In order to successfully claim an address, the CF sending an address
> claimed message shall not receive a contending claim from another CF
> for at least 250 ms.
>
> As stated in "4.4.3.2 - NAME management (NM) message":
> 1) A commanding CF can
> d) request that a CF with a specified NAME transmit the address-
> claimed message with its current NAME.
> 2) A target CF shall
> d) send an address-claimed message in response to a request for a
> matching NAME
>
> Taking the above arguments into account, the 250 ms wait is requested
> only during network initialization.
>
> Do not restart the timer on AC message if both the NAME and the address
> match and so if the address has already been claimed (timer has expired)
> or the AC message has been sent to resolve the contention with another
> CF (timer is still running).
>
> Signed-off-by: Devid Antonio Filoni <devid.filoni@xxxxxxxxxxxxxxxxxxxxx>
Acked-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
> ---
> v1 -> v2: Added ISO 11783-5 standard references
>
> net/can/j1939/address-claim.c | 40 +++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/net/can/j1939/address-claim.c b/net/can/j1939/address-claim.c
> index f33c47327927..ca4ad6cdd5cb 100644
> --- a/net/can/j1939/address-claim.c
> +++ b/net/can/j1939/address-claim.c
> @@ -165,6 +165,46 @@ static void j1939_ac_process(struct j1939_priv *priv, struct sk_buff *skb)
> * leaving this function.
> */
> ecu = j1939_ecu_get_by_name_locked(priv, name);
> +
> + if (ecu && ecu->addr == skcb->addr.sa) {
> + /* The ISO 11783-5 standard, in "4.5.2 - Address claim
> + * requirements", states:
> + * d) No CF shall begin, or resume, transmission on the
> + * network until 250 ms after it has successfully claimed
> + * an address except when responding to a request for
> + * address-claimed.
> + *
> + * But "Figure 6" and "Figure 7" in "4.5.4.2 - Address-claim
> + * prioritization" show that the CF begins the transmission
> + * after 250 ms from the first AC (address-claimed) message
> + * even if it sends another AC message during that time window
> + * to resolve the address contention with another CF.
> + *
> + * As stated in "4.4.2.3 - Address-claimed message":
> + * In order to successfully claim an address, the CF sending
> + * an address claimed message shall not receive a contending
> + * claim from another CF for at least 250 ms.
> + *
> + * As stated in "4.4.3.2 - NAME management (NM) message":
> + * 1) A commanding CF can
> + * d) request that a CF with a specified NAME transmit
> + * the address-claimed message with its current NAME.
> + * 2) A target CF shall
> + * d) send an address-claimed message in response to a
> + * request for a matching NAME
> + *
> + * Taking the above arguments into account, the 250 ms wait is
> + * requested only during network initialization.
> + *
> + * Do not restart the timer on AC message if both the NAME and
> + * the address match and so if the address has already been
> + * claimed (timer has expired) or the AC message has been sent
> + * to resolve the contention with another CF (timer is still
> + * running).
> + */
> + goto out_ecu_put;
> + }
> +
> if (!ecu && j1939_address_is_unicast(skcb->addr.sa))
> ecu = j1939_ecu_create_locked(priv, name);
>
> --
> 2.34.1
>
>
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