Messages in this thread | | | Date | Thu, 14 Dec 2023 18:29:28 +0100 | From | Christian Marangi <> | Subject | Re: [net-next PATCH v7 2/4] net: phy: extend PHY package API to support multiple global address |
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On Thu, Dec 14, 2023 at 11:54:26PM +0000, Russell King (Oracle) wrote: > On Thu, Dec 14, 2023 at 05:54:51PM +0100, Christian Marangi wrote: > > What I don't like is the wrap check. > > > > But I wonder... Isn't it easier to have > > > > unsigned int addr = shared->base_addr + addr_offset; > > > > and check if >= PHY_MAC_ADDR? > > > > Everything is unsigned (so no negative case) and wrap is not possible as > > nothing is downcasted. > > I'm afraid that I LOL'd at "wrap is not possible" ! Of course it's > possible. Here's an example: >
Yes I just think about it and I'm also LOLing at the "not possible"...
> shared->base_addr is 20 > addr_offset is ~0 (or -1 casted to an unsigned int) > addr becomes 19 > > How about: > > if (addr_offset >= PHY_MAX_ADDR) > return -EIO; > > addr = shared->base_addr + addr_offset; > if (addr >= PHY_MAX_ADDR) > return -EIO; > > and then we could keep 'addr' as u8.
Ok just to make sure
static int phy_package_address(struct phy_device *phydev, unsigned int addr_offset) { struct phy_package_shared *shared = phydev->shared; unsigned int addr;
if (addr_offset >= PHY_MAX_ADDR) return -EIO;
addr = shared->base_addr + addr_offset; 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 call u8 addr = phy_package_address(phydev, addr_offset);
Maybe one if can be skipped with the following fun thing?
static int phy_package_address(struct phy_device *phydev, unsigned int addr_offset) { struct phy_package_shared *shared = phydev->shared; u8 base_addr = shared->base_addr;
if (addr_offset >= PHY_MAX_ADDR - base_addr) 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 base_addr + addr_offset; }
(don't hate me it's late here and my brain is half working ahahha)
> > Honestly, I have wondered why the mdio bus address is a signed int, but > never decided to do anything about it. >
Maybe because direct usage of mdiobus_ is discouraged and phy_write will use an addr that is already validated.
-- Ansuel
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