linux-kernel - Re: [PATCH 5/5] staging: fsl-dpaa2/eth: Remove Rx frame size check

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Date:   Tue, 10 Jul 2018 19:45:42 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Ioana Ciocoi Radulescu <ruxandra.radulescu@....com>
Cc:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: Re: [PATCH 5/5] staging: fsl-dpaa2/eth: Remove Rx frame size check

On Tue, Jul 10, 2018 at 03:55:32PM +0000, Ioana Ciocoi Radulescu wrote:
> > -----Original Message-----
> > From: Dan Carpenter [mailto:dan.carpenter@...cle.com]
> > Sent: Monday, July 9, 2018 10:28 PM
> > To: Ioana Ciocoi Radulescu <ruxandra.radulescu@....com>
> > Cc: gregkh@...uxfoundation.org; devel@...verdev.osuosl.org; linux-
> > kernel@...r.kernel.org; Ioana Ciornei <ioana.ciornei@....com>
> > Subject: Re: [PATCH 5/5] staging: fsl-dpaa2/eth: Remove Rx frame size check
> > 
> > On Mon, Jul 09, 2018 at 10:01:11AM -0500, Ioana Radulescu wrote:
> > > @@ -2385,6 +2365,12 @@ static int netdev_init(struct net_device
> > *net_dev)
> > >
> > >  	/* Set MTU upper limit; lower limit is 68B (default value) */
> > >  	net_dev->max_mtu = DPAA2_ETH_MAX_MTU;
> > > +	err = dpni_set_max_frame_length(priv->mc_io, 0, priv->mc_token,
> > > +					(u16)DPAA2_ETH_MFL);
> > 
> > The cast was there in the original code so this is not a comment on this
> > particular patch (which seems fine) but there is no need to cast.
> > 
> > Generally it's best to avoid unnecessary casts.  As a human reader, I
> > find the cast confusing.  It indicates that DPAA2_ETH_MFL somehow
> > requires special handling.  Perhaps it's negative or we are trying to
> > truncate away the high bits.  But neither of those things really make
> > sense.
> > 
> > From a static analysis perspective if DPAA2_ETH_MFL doesn't fit nicely
> > then we would want to generate a warning.  But the cast explicitly
> > disables the check.
> 
> I really don't remember why the cast was there in the first place.
> It doesn't look like it's needed anymore, DPAA2_ETH_MFL has a
> positive value (around 10K) that fits just fine inside a u16.
> 
> I see Greg already applied the patch, so I'll send a separate one to
> remove the cast.

Yeah.  I wasn't saying redo the patch.  That was there in the original
and it's not like it's a bug or anything.

regards,
dan carpenter