diff mbox series

[net-next,v6,7/9] net: dsa: microchip: Add error handling for ksz_switch_macaddr_get()

Message ID 20231019122850.1199821-8-o.rempel@pengutronix.de
State New
Headers
Series net: dsa: microchip: provide Wake on LAN support |

Commit Message

Oleksij Rempel Oct. 19, 2023, 12:28 p.m. UTC 
  Enhance the ksz_switch_macaddr_get() function to handle errors that may
occur during the call to ksz_write8(). Specifically, this update checks
the return value of ksz_write8(), which may fail if regmap ranges
validation is not passed and returns the error code.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/net/dsa/microchip/ksz_common.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

Vladimir Oltean Oct. 19, 2023, 5:13 p.m. UTC | #1 
On Thu, Oct 19, 2023 at 02:28:48PM +0200, Oleksij Rempel wrote:
> Enhance the ksz_switch_macaddr_get() function to handle errors that may
> occur during the call to ksz_write8(). Specifically, this update checks
> the return value of ksz_write8(), which may fail if regmap ranges
> validation is not passed and returns the error code.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
> ---
>  drivers/net/dsa/microchip/ksz_common.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> index 7b05de6fe987..79052a54880c 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -3612,7 +3612,7 @@ int ksz_switch_macaddr_get(struct dsa_switch *ds, int port,
>  	struct ksz_switch_macaddr *switch_macaddr;
>  	struct ksz_device *dev = ds->priv;
>  	const u16 *regs = dev->info->regs;
> -	int i;
> +	int i, ret;
>  
>  	/* Make sure concurrent MAC address changes are blocked */
>  	ASSERT_RTNL();
> @@ -3639,8 +3639,11 @@ int ksz_switch_macaddr_get(struct dsa_switch *ds, int port,
>  	dev->switch_macaddr = switch_macaddr;
>  
>  	/* Program the switch MAC address to hardware */
> -	for (i = 0; i < ETH_ALEN; i++)
> -		ksz_write8(dev, regs[REG_SW_MAC_ADDR] + i, addr[i]);
> +	for (i = 0; i < ETH_ALEN; i++) {
> +		ret = ksz_write8(dev, regs[REG_SW_MAC_ADDR] + i, addr[i]);
> +		if (ret)
> +			return ret;
> +	}

I understand that you intend the error to be fatal, but this leaks memory and a refcount.
Vladimir Oltean Oct. 19, 2023, 5:19 p.m. UTC | #2 
On Thu, Oct 19, 2023 at 08:13:08PM +0300, Vladimir Oltean wrote:
> On Thu, Oct 19, 2023 at 02:28:48PM +0200, Oleksij Rempel wrote:
> > Enhance the ksz_switch_macaddr_get() function to handle errors that may
> > occur during the call to ksz_write8(). Specifically, this update checks
> > the return value of ksz_write8(), which may fail if regmap ranges
> > validation is not passed and returns the error code.
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> > Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> > Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
> > ---
> >  drivers/net/dsa/microchip/ksz_common.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> > index 7b05de6fe987..79052a54880c 100644
> > --- a/drivers/net/dsa/microchip/ksz_common.c
> > +++ b/drivers/net/dsa/microchip/ksz_common.c
> > @@ -3612,7 +3612,7 @@ int ksz_switch_macaddr_get(struct dsa_switch *ds, int port,
> >  	struct ksz_switch_macaddr *switch_macaddr;
> >  	struct ksz_device *dev = ds->priv;
> >  	const u16 *regs = dev->info->regs;
> > -	int i;
> > +	int i, ret;
> >  
> >  	/* Make sure concurrent MAC address changes are blocked */
> >  	ASSERT_RTNL();
> > @@ -3639,8 +3639,11 @@ int ksz_switch_macaddr_get(struct dsa_switch *ds, int port,
> >  	dev->switch_macaddr = switch_macaddr;
> >  
> >  	/* Program the switch MAC address to hardware */
> > -	for (i = 0; i < ETH_ALEN; i++)
> > -		ksz_write8(dev, regs[REG_SW_MAC_ADDR] + i, addr[i]);
> > +	for (i = 0; i < ETH_ALEN; i++) {
> > +		ret = ksz_write8(dev, regs[REG_SW_MAC_ADDR] + i, addr[i]);
> > +		if (ret)
> > +			return ret;
> > +	}
> 
> I understand that you intend the error to be fatal, but this leaks memory and a refcount.

I didn't estimate correctly what would happen.

If ksz_write8() fails as you say, we will leave behind the reference to
dev->switch_macaddr, which points to valid memory. Which means that the
second time around, the call to ksz_switch_macaddr_get() will succeed,
because the driver thinks that the address has been programmed to
hardware, and it is unaware of the previous failure. But it will not
work. Am I correct?

If so, it needs to tear down properly, because if ksz_switch_macaddr_get()
fails once to write to hardware, it should fail always.
diff mbox series

Patch

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 7b05de6fe987..79052a54880c 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -3612,7 +3612,7 @@  int ksz_switch_macaddr_get(struct dsa_switch *ds, int port,
 	struct ksz_switch_macaddr *switch_macaddr;
 	struct ksz_device *dev = ds->priv;
 	const u16 *regs = dev->info->regs;
-	int i;
+	int i, ret;
 
 	/* Make sure concurrent MAC address changes are blocked */
 	ASSERT_RTNL();
@@ -3639,8 +3639,11 @@  int ksz_switch_macaddr_get(struct dsa_switch *ds, int port,
 	dev->switch_macaddr = switch_macaddr;
 
 	/* Program the switch MAC address to hardware */
-	for (i = 0; i < ETH_ALEN; i++)
-		ksz_write8(dev, regs[REG_SW_MAC_ADDR] + i, addr[i]);
+	for (i = 0; i < ETH_ALEN; i++) {
+		ret = ksz_write8(dev, regs[REG_SW_MAC_ADDR] + i, addr[i]);
+		if (ret)
+			return ret;
+	}
 
 	return 0;
 }