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Date: Mon, 5 Jan 2026 15:37:29 -0800
From: Jakub Kicinski <kuba@kernel.org>
To: Qingfang Deng <dqfext@gmail.com>
Cc: David Yang <mmyangfl@gmail.com>, netdev@vger.kernel.org, Andrew Lunn
 <andrew@lunn.ch>, Vladimir Oltean <olteanv@gmail.com>, "David S. Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v3 2/2] net: dsa: yt921x: Protect MIB stats
 with a lock
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In-Reply-To: <20260105025139.2348-1-dqfext@gmail.com>
References: <20260105020905.3522484-1-mmyangfl@gmail.com>
	<20260105020905.3522484-3-mmyangfl@gmail.com>
	<20260105025139.2348-1-dqfext@gmail.com>
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On Mon,  5 Jan 2026 10:51:39 +0800 Qingfang Deng wrote:
> On Mon, 5 Jan 2026 10:09:01 +0800, David Yang wrote:
> > 64bit variables might not be atomic on 32bit architectures, thus cannot
> > be made lock-free. Protect them with a spin lock since get_stats64()
> > cannot sleep.  
> 
> Synchronizing both reads and updates with a spin lock is an overkill.
> See include/linux/u64_stats_sync.h for a better approach.

OTOH seq locks require error prone retry logic, YMMV.