linux-kernel - Re: [PATCH] mfd: omap-usb-tll: handle clk_prepare return code in usbtll_omap

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Message-ID: <CAKwoAfp6iPN0F_kfNbF8xbpX7+Qh+BS55KgmZ5nis0u00vOFhw@mail.gmail.com>
Date: Thu, 7 Nov 2024 12:12:52 +0100
From: Karol P <karprzy7@...il.com>
To: Andreas Kemnade <andreas@...nade.info>
Cc: aaro.koskinen@....fi, khilman@...libre.com, rogerq@...nel.org, 
	tony@...mide.com, lee@...nel.org, linux-omap@...r.kernel.org, 
	linux-kernel@...r.kernel.org, skhan@...uxfoundation.org
Subject: Re: [PATCH] mfd: omap-usb-tll: handle clk_prepare return code in usbtll_omap_probe

On Thu, 7 Nov 2024 at 00:15, Andreas Kemnade <andreas@...nade.info> wrote:
>
> Am Wed,  6 Nov 2024 23:33:24 +0100
> schrieb Karol Przybylski <karprzy7@...il.com>:
>
> > clk_prepare() is called in usbtll_omap_probe to fill clk array.
> > Return code is not checked, leaving possible error condition unhandled.
> >
> > Added variable to hold return value from clk_prepare() and return statement
> > when it's not successful.
> >
> > Found in coverity scan, CID 1594680
> >
> > Signed-off-by: Karol Przybylski <karprzy7@...il.com>
> > ---
> >  drivers/mfd/omap-usb-tll.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
> > index 0f7fdb99c809..28446b082c85 100644
> > --- a/drivers/mfd/omap-usb-tll.c
> > +++ b/drivers/mfd/omap-usb-tll.c
> > @@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> >       struct device                           *dev =  &pdev->dev;
> >       struct usbtll_omap                      *tll;
> >       void __iomem                            *base;
> > -     int                                     i, nch, ver;
> > +     int                                     i, nch, ver, err;
> >
> >       dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
> >
> > @@ -251,7 +251,11 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> >               if (IS_ERR(tll->ch_clk[i]))
> >                       dev_dbg(dev, "can't get clock : %s\n", clkname);
>
> if you add more intensive error checking, then why is this error
> ignored and not returned?

Thank you for the feedback. It does seem that elevated error checking
is not the way
to go in this case. Do you think it would be good to add a similar
statement instead of
my initial changes? It would look something like this:

+               else {
                        err = clk_prepare(tll->ch_clk[i]);
+                       if (err)
+                               dev_dbg(dev, "clock prepare error for:
%s\n", clkname);
+               }

>
> >               else
> > -                     clk_prepare(tll->ch_clk[i]);
> > +                     err = clk_prepare(tll->ch_clk[i]);
> > +                     if (err) {
> unnatural braces, if (err) is not in the else branch ?!
> > +                             dev_err(dev, "Unable to prepare clock\n");
> > +                             return err;
> > +     }
> >       }
> >
> >       pm_runtime_put_sync(dev);
> and this one is not called if you return early.
>
> Regards,
> Andreas