netdev - Re: [PATCH -next] net: broadcom: Use helper function IS_ERR_OR

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Date: Fri, 18 Aug 2023 21:41:16 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Ruan Jinjie <ruanjinjie@...wei.com>
Cc: netdev@...r.kernel.org,
	Rafał Miłecki <rafal@...ecki.pl>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Doug Berger <opendmb@...il.com>,
	Florian Fainelli <florian.fainelli@...adcom.com>
Subject: Re: [PATCH -next] net: broadcom: Use helper function IS_ERR_OR_NULL()

On Thu, Aug 17, 2023 at 05:01:51PM +0800, Ruan Jinjie wrote:
> 
> 
> On 2023/8/17 15:19, Leon Romanovsky wrote:
> > On Wed, Aug 16, 2023 at 05:53:56PM +0800, Ruan Jinjie wrote:
> >> Use IS_ERR_OR_NULL() instead of open-coding it
> >> to simplify the code.
> >>
> >> Signed-off-by: Ruan Jinjie <ruanjinjie@...wei.com>
> >> ---
> >>  drivers/net/ethernet/broadcom/bgmac.c        | 2 +-
> >>  drivers/net/ethernet/broadcom/genet/bcmmii.c | 2 +-
> >>  2 files changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c
> >> index 10c7c232cc4e..4cd7c6abb548 100644
> >> --- a/drivers/net/ethernet/broadcom/bgmac.c
> >> +++ b/drivers/net/ethernet/broadcom/bgmac.c
> >> @@ -1448,7 +1448,7 @@ int bgmac_phy_connect_direct(struct bgmac *bgmac)
> >>  	int err;
> >>  
> >>  	phy_dev = fixed_phy_register(PHY_POLL, &fphy_status, NULL);
> > 
> > When can fixed_phy_register() return NULL?
> > It looks like it returns or valid phy_dev or ERR_PTR().
> 
> It seems the following code has a problem:
> 
> 226 static struct phy_device *__fixed_phy_register(unsigned int irq,
> 227                            struct fixed_phy_status *status,
> 228                            struct device_node *np,
> 229                            struct gpio_desc *gpiod)
> 230 {
> 231     struct fixed_mdio_bus *fmb = &platform_fmb;
> 232     struct phy_device *phy;
> 233     int phy_addr;
> 234     int ret;
> 235
> 236     if (!fmb->mii_bus || fmb->mii_bus->state != MDIOBUS_REGISTERED)
> 237         return ERR_PTR(-EPROBE_DEFER);
> 238
> 239     /* Check if we have a GPIO associated with this fixed phy */
> 240     if (!gpiod) {
> 241         gpiod = fixed_phy_get_gpiod(np);
> 242         if (IS_ERR(gpiod))
> 243             return ERR_CAST(gpiod);
> 244     }
> 
> fixed_phy_get_gpiod() return valid gpio_desc or NULL.If
> fixed_phy_get_gpiod(np) failed, the error can not be returned with
> IS_ERR(gpiod) is true, so the 243 line code is a dead code.

Not really, gpiod can be ERR_PTR(-EPROBE_DEFER) too.

Thanks

> 
> > 
> > Thanks
> > 
> > 
> >> -	if (!phy_dev || IS_ERR(phy_dev)) {
> >> +	if (IS_ERR_OR_NULL(phy_dev)) {
> >>  		dev_err(bgmac->dev, "Failed to register fixed PHY device\n");
> >>  		return -ENODEV;
> >>  	}
> >> diff --git a/drivers/net/ethernet/broadcom/genet/bcmmii.c b/drivers/net/ethernet/broadcom/genet/bcmmii.c
> >> index 0092e46c46f8..aa9a436fb3ce 100644
> >> --- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
> >> +++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
> >> @@ -617,7 +617,7 @@ static int bcmgenet_mii_pd_init(struct bcmgenet_priv *priv)
> >>  		};
> >>  
> >>  		phydev = fixed_phy_register(PHY_POLL, &fphy_status, NULL);
> >> -		if (!phydev || IS_ERR(phydev)) {
> >> +		if (IS_ERR_OR_NULL(phydev)) {
> >>  			dev_err(kdev, "failed to register fixed PHY device\n");
> >>  			return -ENODEV;
> >>  		}
> >> -- 
> >> 2.34.1
> >>
> >>
>