Re: [RFC PATCH v1 1/1] iplink_can: add new CAN FD bittiming parameters: Transmitter Delay Compensation (TDC)

From: Stephen Hemminger
Date: Thu May 06 2021 - 11:50:48 EST


On Thu, 6 May 2021 20:20:07 +0900
Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> wrote:

> + if (tb[IFLA_CAN_TDC_TDCV] && tb[IFLA_CAN_TDC_TDCO] &&
> + tb[IFLA_CAN_TDC_TDCF]) {
> + __u32 *tdcv = RTA_DATA(tb[IFLA_CAN_TDC_TDCV]);
> + __u32 *tdco = RTA_DATA(tb[IFLA_CAN_TDC_TDCO]);
> + __u32 *tdcf = RTA_DATA(tb[IFLA_CAN_TDC_TDCF]);
> +
> + if (is_json_context()) {
> + open_json_object("tdc");
> + print_int(PRINT_JSON, "tdcv", NULL, *tdcv);
> + print_int(PRINT_JSON, "tdco", NULL, *tdco);
> + print_int(PRINT_JSON, "tdcf", NULL, *tdcf);
> + close_json_object();
> + } else {
> + fprintf(f, "\n tdcv %d tdco %d tdcf %d",
> + *tdcv, *tdco, *tdcf);
> + }
> + }
> +

The most common pattern in iproute2 is to let json/non-json be decided
inside the print routine. I search for all instances of fprintf as
indication of broken code. Also these are not signed values so please
print unsigned. The code should use print_nl() to handle the single line
case. Also, there is helper to handle

Something like:
__u32 tdc = rte_getattr_u32(tb[IFLA_CAN_TDC_TDCV]);

open_json_object("tdc");
print_nl();
print_u32(PRINT_ANY, "tdcv", " tdcv %u", tdcv);
...