Re: [PATCH v2 net] net/sched: taprio: enforce minimum value for picos_per_byte

[Jakub Kicinski <kuba@kernel.org>]

On Sat, 26 Jul 2025 10:08:15 +0900 Takamitsu Iwai wrote:
>  #define TAPRIO_FLAGS_INVALID U32_MAX
> +/* Minimum value for picos_per_byte to ensure non-zero duration
> + * for minimum-sized Ethernet frames (ETH_ZLEN = 60).
> + * 60 * 17 > PSEC_PER_NSEC (1000)
> + */
> +#define TAPRIO_PICOS_PER_BYTE_MIN 17
> +

unnecessary new line

>  struct sched_entry {
>  	/* Durations between this GCL entry and the GCL entry where the
> @@ -1300,6 +1306,11 @@ static void taprio_set_picos_per_byte(struct net_device *dev,
>  
>  skip:
>  	picos_per_byte = (USEC_PER_SEC * 8) / speed;
> +	if (picos_per_byte < TAPRIO_PICOS_PER_BYTE_MIN) {
> +		pr_warn("Link speed %d is too high. Schedule may be inaccurate.\n",
> +			speed);
> +		picos_per_byte = TAPRIO_PICOS_PER_BYTE_MIN;

for the path coming in from taprio_change() you should use the extack
to report the warning (if return value is 0 but extack was set CLIs
will print that message as a warning directly to the user)
-- 
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