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Date: Thu, 8 May 2025 09:04:45 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Cosmin Ratiu <cratiu@nvidia.com>, Stanislav Fomichev <sdf@fomichev.me>
Cc: <netdev@vger.kernel.org>, "David S . Miller" <davem@davemloft.net>, Eric
 Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Simon
 Horman <horms@kernel.org>, Saeed Mahameed <saeedm@nvidia.com>, Tariq Toukan
 <tariqt@nvidia.com>, Dragos Tatulea <dtatulea@nvidia.com>
Subject: Re: [PATCH net v2] net: Lock lower level devices when updating
 features
Message-ID: <20250508090445.3b235bcc@kernel.org>
In-Reply-To: <20250508145459.1998067-1-cratiu@nvidia.com>
References: <20250508145459.1998067-1-cratiu@nvidia.com>
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On Thu, 8 May 2025 17:54:59 +0300 Cosmin Ratiu wrote:
>  			lower->wanted_features &= ~feature;
> +			netdev_lock_ops(lower);
>  			__netdev_update_features(lower);
> +			netdev_unlock_ops(lower);
>  
>  			if (unlikely(lower->features & feature))

I'd be slightly tempted to try to cover the accesses to members of
lower, because why not:

			netdev_lock_ops(lower);
 			lower->wanted_features &= ~feature;
 			__netdev_update_features(lower);
			still_enabled = lower->features & feature;
			netdev_unlock_ops(lower);

 			if (unlikely(still_enabled))

WDYT?