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Date: Mon, 30 Jun 2025 12:18:36 +0100
From: Simon Horman <horms@kernel.org>
To: Alok Tiwari <alok.a.tiwari@oracle.com>
Cc: sgoutham@marvell.com, andrew+netdev@lunn.ch, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net v2] net: thunderx: avoid direct MTU assignment after
 WRITE_ONCE()
Message-ID: <20250630111836.GE41770@horms.kernel.org>
References: <20250629051540.518216-1-alok.a.tiwari@oracle.com>
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In-Reply-To: <20250629051540.518216-1-alok.a.tiwari@oracle.com>

On Sat, Jun 28, 2025 at 10:15:37PM -0700, Alok Tiwari wrote:

...

> @@ -1589,16 +1588,18 @@ static int nicvf_change_mtu(struct net_device *netdev, int new_mtu)
>  		return -EINVAL;
>  	}
>  
> -	WRITE_ONCE(netdev->mtu, new_mtu);
>  
> -	if (!netif_running(netdev))
> +	if (!netif_running(netdev)) {
> +		WRITE_ONCE(netdev->mtu, new_mtu);
>  		return 0;
> +	}
>  
>  	if (nicvf_update_hw_max_frs(nic, new_mtu)) {
> -		netdev->mtu = orig_mtu;
>  		return -EINVAL;
>  	}

nit: curly brackets should be removed here, but see further comment below.

>  
> +	WRITE_ONCE(netdev->mtu, new_mtu);
> +
>  	return 0;
>  }

Could this be more succinctly expressed as follows?
(Completely untested!)

	if (netif_running(netdev) && nicvf_update_hw_max_frs(nic, new_mtu))
		return -ENIVAL;

	WRITE_ONCE(netdev->mtu, new_mtu);

	return 0;