On Sun, Dec 31, 2017 at 10:07:14AM +0000, Russell King - ARM Linux wrote:
> On Sun, Dec 31, 2017 at 09:10:39AM +0100, Andrew Lunn wrote:
> > > +/**
> > > + * phy_save_page() - take the bus lock and save the current page
> > > + * @phydev: a pointer to a &struct phy_device
> > > + *
> > > + * Take the MDIO bus lock, and return the current page number. On error,
> > > + * returns a negative errno. phy_restore_page() must be called after this
> > > + * to release the lock even on failure.
> > > + */
> > > +int phy_save_page(struct phy_device *phydev)
> > > +{
> > > + mutex_lock(&phydev->mdio.bus->mdio_lock);
> > > + return __phy_read_page(phydev);
> > > +}
> > > +EXPORT_SYMBOL_GPL(phy_save_page);
> > > +
> > > +/**
> > > + * phy_select_page() - take the bus lock, save the current page, and set
> > > a page
> > > + * @phydev: a pointer to a &struct phy_device
> > > + * @page: desired page
> > > + *
> > > + * Take the MDIO bus lock to protect against concurrent access, save the
> > > + * current PHY page, and set the current page. On error, returns a
> > > + * negative errno, otherwise returns the previous page number.
> > > + * phy_restore_page() must be called after this to restore the page
> > > + * number (if this call was successful) and release the lock.
> >
> > Hi Russell
> >
> > This comment seems wrong. It looks like you need to call
> > phy_restore_page() on error as well. I think the text in () should be
> > removed, and add the "even on failure" which the previous function
> > states.
>
> It's one of those slightly confusing bits of English, and I doubt
> there's a way to express it better.
>
> phy_restore_page() must be called after this to [restore the page
> number (if this call was successful) and] release the lock.
>
> I could use:
>
> phy_restore_page() must always be called to release the lock,
> and restore the page number if this call was successful.
>
> but that can still be read in an ambiguous manner.
I've decided to solve this by changing it to:
+ * phy_restore_page() must always be called after this, irrespective
+ * of success or failure of this call.
iow, not explaining /why/.
--
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