netdev - Re: [PATCH v3] netfilter: nft_counter: Fix reset of counters on 32bit archs

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Message-ID: <aYH-Mr0Hy7EfivBt@strlen.de>
Date: Tue, 3 Feb 2026 14:54:58 +0100
From: Florian Westphal <fw@...len.de>
To: anders.grahn@...il.com
Cc: Pablo Neira Ayuso <pablo@...filter.org>, Phil Sutter <phil@....cc>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-kernel@...r.kernel.org, netfilter-devel@...r.kernel.org,
	coreteam@...filter.org, netdev@...r.kernel.org
Subject: Re: [PATCH v3] netfilter: nft_counter: Fix reset of counters on
 32bit archs

anders.grahn@...il.com <anders.grahn@...il.com> wrote:
> From: Anders Grahn <anders.grahn@...il.com>
> 
> nft_counter_reset() calls u64_stats_add() with a negative value to reset
> the counter. This will work on 64bit archs, hence the negative value
> added will wrap as a 64bit value which then can wrap the stat counter as
> well.
> 
> On 32bit archs, the added negative value will wrap as a 32bit value and
> _not_ wrapping the stat counter properly. In most cases, this would just
> lead to a very large 32bit value being added to the stat counter.
> 
> Fix by introducing u64_stats_sub().

Thanks Anders.

I will apply this in the next days unless there is a NACK from
netdev maintainers.