linux-kernel - RE: [PATCH net-next v3] net: mvneta: Use min macro

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Message-ID: <d23dfbf563714d7090d163a075ca9a51@AcuMS.aculab.com>
Date: Sun, 1 Sep 2024 10:52:38 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Yan Zhen' <yanzhen@...o.com>, "marcin.s.wojtas@...il.com"
	<marcin.s.wojtas@...il.com>, "davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"opensource.kernel@...o.com" <opensource.kernel@...o.com>
Subject: RE: [PATCH net-next v3] net: mvneta: Use min macro

From: Yan Zhen
> Sent: 30 August 2024 02:04
> To: marcin.s.wojtas@...il.com; davem@...emloft.net; edumazet@...gle.com; kuba@...nel.org;
> 
> Using the real macro is usually more intuitive and readable,
> When the original file is guaranteed to contain the minmax.h header file
> and compile correctly.
> 
> Signed-off-by: Yan Zhen <yanzhen@...o.com>
> ---
> 
> Changes in v3:
> - Rewrite the subject.
> 
>  drivers/net/ethernet/marvell/mvneta.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index d72b2d5f96db..08d277165f40 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -4750,8 +4750,7 @@ mvneta_ethtool_set_ringparam(struct net_device *dev,
> 
>  	if ((ring->rx_pending == 0) || (ring->tx_pending == 0))
>  		return -EINVAL;
> -	pp->rx_ring_size = ring->rx_pending < MVNETA_MAX_RXD ?
> -		ring->rx_pending : MVNETA_MAX_RXD;
> +	pp->rx_ring_size = umin(ring->rx_pending, MVNETA_MAX_RXD);

Why did you use umin() instead of min() ?

> 
>  	pp->tx_ring_size = clamp_t(u16, ring->tx_pending,
>  				   MVNETA_MAX_SKB_DESCS * 2, MVNETA_MAX_TXD);

Hmmm how about a patch to fix the bug in that line?
A typical example of the complete misuse of the '_t' variants.
The fact that the LHS is u16 doesn't mean that it is anyway
correct to cast the RHS value to u16.
In this case if someone tries to set the ring size to 64k they'll
get the minimum supported size and not the maximum.

	David

> --
> 2.34.1
> 

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