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Message-ID: <ZXs14wrGKGtTfiui@shell.armlinux.org.uk>
Date: Thu, 14 Dec 2023 17:05:39 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Christian Marangi <ansuelsmth@...il.com>
Cc: Florian Fainelli <florian.fainelli@...adcom.com>,
Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
Andrew Lunn <andrew@...n.ch>,
Heiner Kallweit <hkallweit1@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Vladimir Oltean <olteanv@...il.com>,
David Epping <david.epping@...singlinkelectronics.com>,
Harini Katakam <harini.katakam@....com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [net-next PATCH v7 2/4] net: phy: extend PHY package API to
support multiple global address
On Thu, Dec 14, 2023 at 01:10:24PM +0100, Christian Marangi wrote:
> @@ -1998,46 +1999,54 @@ int __phy_hwtstamp_set(struct phy_device *phydev,
> struct kernel_hwtstamp_config *config,
> struct netlink_ext_ack *extack);
>
> -static inline int phy_package_read(struct phy_device *phydev, u32 regnum)
> +static inline int phy_package_read(struct phy_device *phydev,
> + unsigned int addr_offset, u32 regnum)
> {
> struct phy_package_shared *shared = phydev->shared;
> + u8 addr = shared->base_addr + addr_offset;
>
> - if (!shared)
> + if (addr >= PHY_MAX_ADDR)
> return -EIO;
I did notice that you're using u8 in patch 1 as well - and while it's
fine in patch 1 (because we validate the range of the value we will
assign to that variable) that is not the case here.
Yes, shared->base_addr is a u8, but addr_offset is an unsigned int,
and this is implicitly cast-down to a u8 in the calculation of addr,
chopping off the bits above bit 7.
How about this approach:
static int phy_package_address(struct phy_device *phydev,
unsigned int addr_offset)
{
struct phy_package_shared *shared = phydev->shared;
unsigned int addr = shared->addr + addr_offset;
/* detect wrap */
if (addr < addr_offset)
return -EIO;
/* detect invalid address */
if (addr >= PHY_ADDR_MAX)
return -EIO;
/* we know that addr will be in the range 0..31 and thus the
* implicit cast to a signed int is not a problem.
*/
return addr;
}
and then these functions all become:
int addr = phy_package_address(phydev, addr_offset);
if (addr < 0)
return addr;
I'll give you that this is belt and braces, but it avoids problems
should a negative errno value be passed in as addr_offset (which will
be cast to a very large positive integer.)
Andrew, any opinions on how far this should be taken?
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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