Messages in this thread | | | Date | Wed, 11 May 2022 11:45:24 +0100 | From | "Russell King (Oracle)" <> | Subject | Re: [PATCH v2 net] net: phy: mscc: Add error check when __phy_read() failed |
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On Tue, May 10, 2022 at 10:22:45PM +0800, Wan Jiabing wrote: > 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") > Signed-off-by: Wan Jiabing <wanjiabing@vivo.com> > --- > Changelog: > v2: > - Sort variable declaration and add a detailed comment. > --- > drivers/net/phy/mscc/mscc_macsec.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/phy/mscc/mscc_macsec.c b/drivers/net/phy/mscc/mscc_macsec.c > index b7b2521c73fb..58ad11a697b6 100644 > --- a/drivers/net/phy/mscc/mscc_macsec.c > +++ b/drivers/net/phy/mscc/mscc_macsec.c > @@ -22,9 +22,9 @@ > 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; > + > failed: > phy_restore_page(phydev, rc, rc); > > - return (val_h << 16) | val_l; > + return ret; > }
This is still wrong - phy_restore_page() can fail to retore the page.
It's rather unfortunate that you need to return a u32, where the high values become negative ints, which means you can't use phy_restore_page() as it's supposed to be used.
If you fail to read from the PHY, is returning zero acceptable?
I think what you should be doing at the very least is:
rc = phy_select_page(phydev, MSCC_PHY_PAGE_MACSEC); if (rc < 0) goto failed;
rc = __phy_write(phydev, MSCC_EXT_PAGE_MACSEC_20, ...); if (rc < 0) goto failed;
...
rc = __phy_write(phydev, MSCC_EXT_PAGE_MACSEC_19, ...); if (rc < 0) goto failed;
... do { val = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_19); if (val < 0) { rc = val; goto failed; } } while (...);
val_l = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_17); if (val_l < 0) { rc = val_l; goto failed; }
val_h = __phy_read(phydev, MSCC_EXT_PAGE_MACSEC_18); if (val_h < 0) rc = val_h;
failed: rc = phy_restore_page(phgydev, rc, 0);
return rc < 0 ? 0 : val_h << 16 | val_l;
Which means that if any of the PHY IO functions fail at any point, this returns zero.
-- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
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