Re: [PATCH net] net: dsa: felix: fix taprio guard band overflow at 10Mbps with jumbo frames

From: patchwork-bot+netdevbpf
Date: Thu Jun 15 2023 - 02:10:27 EST


Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@xxxxxxxxxx>:

On Tue, 13 Jun 2023 20:09:07 +0300 you wrote:
> The DEV_MAC_MAXLEN_CFG register contains a 16-bit value - up to 65535.
> Plus 2 * VLAN_HLEN (4), that is up to 65543.
>
> The picos_per_byte variable is the largest when "speed" is lowest -
> SPEED_10 = 10. In that case it is (1000000L * 8) / 10 = 800000.
>
> Their product - 52434400000 - exceeds 32 bits, which is a problem,
> because apparently, a multiplication between two 32-bit factors is
> evaluated as 32-bit before being assigned to a 64-bit variable.
> In fact it's a problem for any MTU value larger than 5368.
>
> [...]

Here is the summary with links:
- [net] net: dsa: felix: fix taprio guard band overflow at 10Mbps with jumbo frames
https://git.kernel.org/netdev/net/c/6ac7a27a8b07

You are awesome, thank you!
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