[EXT] Re: [PATCH v5 1/2] net: stmmac: add support for platform specific reset

[Shenwei Wang]

> -----Original Message-----
> From: Simon Horman <simon.horman at corigine.com>
> Sent: Monday, April 3, 2023 2:50 PM
> To: Shenwei Wang <shenwei.wang at nxp.com>
> Cc: David S. Miller <davem at davemloft.net>; Eric Dumazet
> <edumazet at google.com>; Jakub Kicinski <kuba at kernel.org>; Paolo Abeni
> <pabeni at redhat.com>; Shawn Guo <shawnguo at kernel.org>; Sascha Hauer
> <s.hauer at pengutronix.de>; Pengutronix Kernel Team <kernel at pengutronix.de>;
> Giuseppe Cavallaro <peppe.cavallaro at st.com>; Alexandre Torgue
> <alexandre.torgue at foss.st.com>; Jose Abreu <joabreu at synopsys.com>; Fabio
> Estevam <festevam at gmail.com>; dl-linux-imx <linux-imx at nxp.com>; Maxime
> Coquelin <mcoquelin.stm32 at gmail.com>; Wong Vee Khee
> <veekhee at apple.com>; Kurt Kanzenbach <kurt at linutronix.de>; Mohammad
> Athari Bin Ismail <mohammad.athari.ismail at intel.com>; Andrey Konovalov
> <andrey.konovalov at linaro.org>; Jochen Henneberg <jh at henneberg-
> systemdesign.com>; Tan Tee Min <tee.min.tan at linux.intel.com>;
> netdev at vger.kernel.org; linux-arm-kernel at lists.infradead.org; linux-stm32 at st-
> md-mailman.stormreply.com; imx at lists.linux.dev
> Subject: [EXT] Re: [PATCH v5 1/2] net: stmmac: add support for platform specific
> reset
> 
> Caution: EXT Email
> 
> On Mon, Apr 03, 2023 at 10:24:07AM -0500, Shenwei Wang wrote:
> > This patch adds support for platform-specific reset logic in the
> > stmmac driver. Some SoCs require a different reset mechanism than the
> > standard dwmac IP reset. To support these platforms, a new function
> > pointer 'fix_soc_reset' is added to the plat_stmmacenet_data structure.
> > The stmmac_reset in hwif.h is modified to call the 'fix_soc_reset'
> > function if it exists. This enables the driver to use the
> > platform-specific reset logic when necessary.
> >
> > Signed-off-by: Shenwei Wang <shenwei.wang at nxp.com>
> > ---
> >  v5:
> >   - add the missing __iomem tag in the stmmac_reset definition.
> >
> >  drivers/net/ethernet/stmicro/stmmac/hwif.c | 10 ++++++++++
> > drivers/net/ethernet/stmicro/stmmac/hwif.h |  3 +--
> >  include/linux/stmmac.h                     |  1 +
> >  3 files changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > index bb7114f970f8..0eefa697ffe8 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > @@ -87,6 +87,16 @@ static int stmmac_dwxlgmac_quirks(struct stmmac_priv
> *priv)
> >       return 0;
> >  }
> >
> > +int stmmac_reset(struct stmmac_priv *priv, void __iomem *ioaddr) {
> > +     struct plat_stmmacenet_data *plat = priv ? priv->plat : NULL;
> 
> Here the case where priv is NULL is handled.
> 
> > +
> > +     if (plat && plat->fix_soc_reset)
> > +             return plat->fix_soc_reset(plat, ioaddr);
> > +
> > +     return stmmac_do_callback(priv, dma, reset, ioaddr);
> 
> But this will dereference priv unconditionally.
> 

The original macro implementation assumes that the priv pointer will not be NULL. However, adding 
an extra condition check for priv in the stmmac_reset() function can ensure that the code is more 
robust and secure.

Thanks,
Shenwei

> I think perhaps this is code that I suggested.
> If so, sorry about not noticing this then.
> 
> > +}
> > +
> >  static const struct stmmac_hwif_entry {
> >       bool gmac;
> >       bool gmac4;
> 
> ...