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SubjectRe: [PATCH v2 net] net: phy: mscc: Add error check when __phy_read() failed
Date
Hello,

Quoting Wan Jiabing (2022-05-10 16:22:45)
> Calling __phy_read() might return a negative error code. Use 'int'
> to declare variables which call __phy_read() and also add error check
> for them.
>
> The numerous callers of vsc8584_macsec_phy_read() don't expect it to
> fail. So don't return the error code from __phy_read(), but also don't
> return random values if it does fail.
>
> Fixes: fa164e40c53b ("net: phy: mscc: split the driver into separate files")

Does this fix an actual issue or was this found by code inspection? If
that is not fixing a real issue I don't think it should go to stable
trees.

Also this is not the right commit, the __phy_read call was introduced
before splitting the file.

> static u32 vsc8584_macsec_phy_read(struct phy_device *phydev,
> enum macsec_bank bank, u32 reg)
> {
> - u32 val, val_l = 0, val_h = 0;
> + int rc, val, val_l, val_h;
> unsigned long deadline;
> - int rc;
> + u32 ret = 0;
>
> rc = phy_select_page(phydev, MSCC_PHY_PAGE_MACSEC);
> if (rc < 0)
> @@ -47,15 +47,20 @@ static u32 vsc8584_macsec_phy_read(struct phy_device *phydev,
> deadline = jiffies + msecs_to_jiffies(PROC_CMD_NCOMPLETED_TIMEOUT_MS);
> do {
> val = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_19);
> + if (val < 0)
> + goto failed;
> } while (time_before(jiffies, deadline) && !(val & MSCC_PHY_MACSEC_19_CMD));
>
> val_l = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_17);
> val_h = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_18);
>
> + if (val_l > 0 && val_h > 0)
> + ret = (val_h << 16) | val_l;

Both values have to be non-0 for the function to return a value? I
haven't checked but I would assume it is valid to have one of the two
being 0.

> failed:
> phy_restore_page(phydev, rc, rc);
>
> - return (val_h << 16) | val_l;
> + return ret;
> }

Thanks,
Antoine

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