linux-kernel - Re: [PATCH v1] ethernet: marvell: Use min macro

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Message-ID: <20240827175745.GS1368797@kernel.org>
Date: Tue, 27 Aug 2024 18:57:45 +0100
From: Simon Horman <horms@...nel.org>
To: Yan Zhen <yanzhen@...o.com>
Cc: marcin.s.wojtas@...il.com, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, opensource.kernel@...o.com
Subject: Re: [PATCH v1] ethernet: marvell: Use min macro

On Tue, Aug 27, 2024 at 06:54:08PM +0100, Simon Horman wrote:
> On Tue, Aug 27, 2024 at 07:58:48PM +0800, Yan Zhen wrote:
> > 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>
> > ---
> >  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..415d2b9e63f9 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 = min(ring->rx_pending, MVNETA_MAX_RXD);
> 
> Given that the type of ring->rx_pending is __32, and MVNETA_MAX_RXD is
> a positive value.

Sorry, I hit send to soon. What I wanted to say is:

I think that it is appropriate to use umin() here.
Because:
1) As I understand things, the type of MVNETA_MAX_RXD is signed,
   but it always holds a positive value
2) ring->rx_pending is unsigned

> See: 80fcac55385c ("minmax: add umin(a, b) and umax(a, b)")
>      https://git.kernel.org/torvalds/c/80fcac55385c