linux-kernel - Re: [PATCH net-next 1/3] net: dsa: sync dsa_mall_policer_tc_entry with FLOW_ACTION

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Message-ID: <20260129152201.389fac74@kernel.org>
Date: Thu, 29 Jan 2026 15:22:01 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: David Yang <mmyangfl@...il.com>
Cc: netdev@...r.kernel.org, Vladimir Oltean <vladimir.oltean@....com>,
 Claudiu Manoil <claudiu.manoil@....com>, Alexandre Belloni
 <alexandre.belloni@...tlin.com>, UNGLinuxDriver@...rochip.com, Andrew Lunn
 <andrew@...n.ch>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Simon Horman
 <horms@...nel.org>, Russell King <linux@...linux.org.uk>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/3] net: dsa: sync dsa_mall_policer_tc_entry
 with FLOW_ACTION_POLICE

On Mon, 26 Jan 2026 14:13:29 +0800 David Yang wrote:
> -	policer->rate_bytes_per_sec = act->police.rate_bytes_ps;
> -	policer->burst = act->police.burst;
> +	/* so sad, flow_offload.h did not export the type of act->police, and
> +	 * it's a nightmare to copy it field by field
> +	 */
> +	static_assert(sizeof(act->police) == sizeof(*policer));
> +	memcpy(policer, &act->police, sizeof(*policer));

This is of course an unacceptable hack. Nobody will realize that
there's a layout dependency here, not to mention struct randomization.
If someone adds fields presumably they will have to update
dsa_mall_policer_tc_entry_type() anyway, so we aren't saving much with this hack