RE: [PATCH v3] net: stmmac: fix maxmtu assignment to be within valid range

[Kweh, Hock Leong]

> -----Original Message-----
> From: Joao Pinto [mailto:Joao.Pinto@xxxxxxxxxxxx]
> Sent: Saturday, January 07, 2017 12:58 AM
> To: Kweh, Hock Leong <hock.leong.kweh@xxxxxxxxx>; David S. Miller
> <davem@xxxxxxxxxxxxx>; Joao Pinto <Joao.Pinto@xxxxxxxxxxxx>; Giuseppe
> CAVALLARO <peppe.cavallaro@xxxxxx>; seraphin.bonnaffe@xxxxxx; Jarod
> Wilson <jarod@xxxxxxxxxx>; Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Cc: Alexandre TORGUE <alexandre.torgue@xxxxxxxxx>; Joachim Eastwood
> <manabian@xxxxxxxxx>; Niklas Cassel <niklas.cassel@xxxxxxxx>; Johan Hovold
> <johan@xxxxxxxxxx>; pavel@xxxxxx; lars.persson@xxxxxxxx; netdev
> <netdev@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>
> Subject: Re: [PATCH v3] net: stmmac: fix maxmtu assignment to be within valid
> range
> 
> 
> Hi Wilson,
> 
> Às 12:49 AM de 1/7/2017, Kweh, Hock Leong escreveu:
> > From: "Kweh, Hock Leong" <hock.leong.kweh@xxxxxxxxx>
> >
> > There is no checking valid value of maxmtu when getting it from device tree.
> > This resolution added the checking condition to ensure the assignment is
> > made within a valid range.
> >
> > Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@xxxxxxxxx>
> > ---
> > changelog v3:
> > * print the warning message only if maxmtu < min_mtu
> > * add maxmtu = JUMBO_LEN at stmmac_pci.c to follow stmmac_platform.c
> >
> > changelog v2:
> > * correction of "devicetree" to "device tree" reported by Andy
> > * print warning message while maxmtu is not in valid range
> >
> >  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |    8 +++++++-
> >  drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c  |    4 ++++
> >  2 files changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > index 92ac006..ce74ae6 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > @@ -3345,8 +3345,14 @@ int stmmac_dvr_probe(struct device *device,
> >  		ndev->max_mtu = JUMBO_LEN;
> >  	else
> >  		ndev->max_mtu = SKB_MAX_HEAD(NET_SKB_PAD +
> NET_IP_ALIGN);
> > -	if (priv->plat->maxmtu < ndev->max_mtu)
> > +
> > +	if ((priv->plat->maxmtu < ndev->max_mtu) &&
> > +	    (priv->plat->maxmtu >= ndev->min_mtu))
> >  		ndev->max_mtu = priv->plat->maxmtu;
> > +	else if (priv->plat->maxmtu < ndev->min_mtu)
> > +		netdev_warn(priv->dev,
> > +			    "%s: warning: maxmtu having invalid value (%d)\n",
> > +			    __func__, priv->plat->maxmtu);
> >
> >  	if (flow_ctrl)
> >  		priv->flow_ctrl = FLOW_AUTO;	/* RX/TX pause on */
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
> > index a283177..e539afe 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
> > @@ -204,6 +204,10 @@ static int stmmac_pci_probe(struct pci_dev *pdev,
> >
> >  	pci_set_master(pdev);
> >
> > +	/* Set the maxmtu to a default of JUMBO_LEN in case the
> > +	 * parameter is not defined for the device.
> > +	 */
> > +	plat->maxmtu = JUMBO_LEN;
> 
> I suggest to put this configuration in one of the default config functions.
> 
> Tahnks.
> 

My original thought is to have one line for all *_default_data() instead of having
multiple same line inside each *_default_data(). If this is not a big concern of
future expand, I can do that. Thanks.

> >  	if (info) {
> >  		info->pdev = pdev;
> >  		if (info->setup) {
> >