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From: Jakub Kicinski <kuba@kernel.org>
To: Takamitsu Iwai <takamitz@amazon.co.jp>
Cc: Vinicius Costa Gomes <vinicius.gomes@intel.com>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Jiri Pirko <jiri@resnulli.us>, <netdev@vger.kernel.org>,
	Kuniyuki Iwashima <kuniyu@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
	Vladimir Oltean <olteanv@gmail.com>, <takamitz@amazon.com>,
	<syzbot+398e1ee4ca2cac05fddb@syzkaller.appspotmail.com>
Subject: Re: [PATCH v2 net] net/sched: taprio: enforce minimum value for picos_per_byte
Date: Sat, 26 Jul 2025 11:37:43 -0700	[thread overview]
Message-ID: <20250726113743.0e9aad80@kernel.org> (raw)
In-Reply-To: <20250726010815.20198-1-takamitz@amazon.co.jp>

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)
-- 
pw-bot: cr

  reply	other threads:[~2025-07-26 18:37 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-26  1:08 [PATCH v2 net] net/sched: taprio: enforce minimum value for picos_per_byte Takamitsu Iwai
2025-07-26 18:37 ` Jakub Kicinski [this message]
2025-07-27  7:22   ` Takamitsu Iwai

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