Re: [PATCH net-next v2 2/4] net: phy: micrel: Introduce lanphy_modify_page_reg

The 07/24/2025 21:41, Russell King (Oracle) wrote:

Hi Russell,

On Thu, Jul 24, 2025 at 10:08:24PM +0200, Horatiu Vultur wrote:

quoted

+static int lanphy_modify_page_reg(struct phy_device *phydev, int page, u16 addr,
+                               u16 mask, u16 set)
+{
+     int new, ret;
+
+     ret = lanphy_read_page_reg(phydev, page, addr);
+     if (ret < 0)
+             return ret;
+
+     new = (ret & ~mask) | set;
+     if (new == ret)
+             return 0;
+
+     ret = lanphy_write_page_reg(phydev, page, addr, new);

Please implement this more safely. Another user could jump in between
the read and the write and change this same register.

        phy_lock_mdio_bus(phydev);
        __phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL, page);
        __phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, addr);
        __phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL,
                    (page | LAN_EXT_PAGE_ACCESS_CTRL_EP_FUNC));
        ret = __phy_modify_changed(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA,
                                   mask, set);
        if (ret < 0)
                phydev_err(phydev, "Error: phy_modify has returned error %d\n",
                           ret);

unlock:
        phy_unlock_mdio_bus(phydev);

        return ret;

is all that it'll take (assuming the control/address register doesn't
need to be rewritten.)

Thanks, I will look into this.

--
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-- 
/Horatiu