linux-kernel - Re: [PATCH v2] ice: use min_t() to make code cleaner in ice

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Message-Id: <20220322175038.2691665-1-alexandr.lobakin@intel.com>
Date:   Tue, 22 Mar 2022 18:50:38 +0100
From:   Alexander Lobakin <alexandr.lobakin@...el.com>
To:     David Laight <David.Laight@...LAB.COM>
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        "'Wan Jiabing'" <wanjiabing@...o.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] ice: use min_t() to make code cleaner in ice_gnss

From: David Laight <David.Laight@...LAB.COM>
Date: Mon, 21 Mar 2022 16:02:20 +0000

> From: Wan Jiabing
> > Sent: 21 March 2022 14:00
> >
> > Fix the following coccicheck warning:
> > ./drivers/net/ethernet/intel/ice/ice_gnss.c:79:26-27: WARNING opportunity for min()
> >
> > Signed-off-by: Wan Jiabing <wanjiabing@...o.com>
> > ---
> > Changelog:
> > v2:
> > - Use typeof(bytes_left) instead of u8.
> > ---
> >  drivers/net/ethernet/intel/ice/ice_gnss.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/ice/ice_gnss.c b/drivers/net/ethernet/intel/ice/ice_gnss.c
> > index 35579cf4283f..57586a2e6dec 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_gnss.c
> > +++ b/drivers/net/ethernet/intel/ice/ice_gnss.c
> > @@ -76,8 +76,7 @@ static void ice_gnss_read(struct kthread_work *work)
> >  	for (i = 0; i < data_len; i += bytes_read) {
> >  		u16 bytes_left = data_len - i;
> 
> Oh FFS why is that u16?
> Don't do arithmetic on anything smaller than 'int'

Any reasoning? I don't say it's good or bad, just want to hear your
arguments (disasms, perf and object code measurements) etc.

> 
> 	David
> 
> >
> > -		bytes_read = bytes_left < ICE_MAX_I2C_DATA_SIZE ? bytes_left :
> > -					  ICE_MAX_I2C_DATA_SIZE;
> > +		bytes_read = min_t(typeof(bytes_left), bytes_left, ICE_MAX_I2C_DATA_SIZE);
> >
> >  		err = ice_aq_read_i2c(hw, link_topo, ICE_GNSS_UBX_I2C_BUS_ADDR,
> >  				      cpu_to_le16(ICE_GNSS_UBX_EMPTY_DATA),
> > --
> > 2.35.1
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)

Thanks,
Al