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Date: Fri, 28 Aug 2026 14:10:48 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Koichiro Den <den@valinux.co.jp>
Cc: Simon Horman <horms@kernel.org>, Jon Mason <jdmason@kudzu.us>, Dave
 Jiang <dave.jiang@intel.com>, Allen Hubbe <allenbh@gmail.com>, Andrew Lunn
 <andrew+netdev@lunn.ch>, "David S. Miller" <davem@davemloft.net>, Eric
 Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>,
 netdev@vger.kernel.org, ntb@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net v2] net: ntb_netdev: Fix statistics races
Message-ID: <20260828141048.685b9e9a@kernel.org>
In-Reply-To: <20260828134957.5b95472b@kernel.org>
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	<20260828134957.5b95472b@kernel.org>
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On Fri, 28 Aug 2026 13:49:57 -0700 Jakub Kicinski wrote:
> On Sat, 29 Aug 2026 00:41:22 +0900 Koichiro Den wrote:
> > Note that transport callbacks may still complete after
> > unregister_netdev(), so tie the tstats lifetime to the client device.  
> 
> We shouldn't really call devm_netdev_alloc_pcpu_stats() for types
> of stats declared by netdev core. We should set the pointer type
> like you did in v1.
> 
> Could you instead fix the fact that the Tx callback runs on 
> an unregistered device? Maybe just wrap the whole body of
> ntb_netdev_tx_handler() in RCU and check 
> 
> 	READ_ONCE(ndev->reg_state) == NETREG_REGISTERED
> 
> ?

Maybe it's over-complicating. IDK.