linux-kernel - Re: [PATCH] drivers: fwnode: fix fwnode_irq_get

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Message-ID: <Y1eTj2v1cioIMwsV@kroah.com>
Date:   Tue, 25 Oct 2022 09:43:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Matti Vaittinen <mazziesaccount@...il.com>
Cc:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Wolfram Sang <wsa@...nel.org>,
        Akhil R <akhilrajeev@...dia.com>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: fwnode: fix fwnode_irq_get_byname() kerneldoc

On Tue, Oct 25, 2022 at 10:17:21AM +0300, Matti Vaittinen wrote:
> ti 25. lokak. 2022 klo 10.06 Matti Vaittinen
> (mazziesaccount@...il.com) kirjoitti:
> >
> > Hi Sakari,
> >
> > On 10/25/22 09:48, Sakari Ailus wrote:
> > > Moi,
> > >
> > > On Tue, Oct 25, 2022 at 08:24:24AM +0300, Matti Vaittinen wrote:
> > >> The fwnode_irq_get_byname() may return zero on device-tree mapping
> > >> error. Fix documentation to reflect this as current documentation
> > >> suggests check:
> > >>
> > >> if (ret < 0)
> > >> is enough to detect the errors. This is not the case.
> > >>
> > >> Add zero as a return value indicating error.
> > >>
> > >> Fixes: ca0acb511c21 ("device property: Add fwnode_irq_get_byname")
> > >> Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > >> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
> > >> ---
> > >>   drivers/base/property.c | 2 +-
> > >>   1 file changed, 1 insertion(+), 1 deletion(-)
> > >>
> > >> diff --git a/drivers/base/property.c b/drivers/base/property.c
> > >> index 4d6278a84868..df437d10aa08 100644
> > >> --- a/drivers/base/property.c
> > >> +++ b/drivers/base/property.c
> > >> @@ -960,7 +960,7 @@ EXPORT_SYMBOL(fwnode_irq_get);
> > >>    * string.
> > >>    *
> > >>    * Return:
> > >> - * Linux IRQ number on success, or negative errno otherwise.
> > >> + * Linux IRQ number on success, zero or negative errno otherwise.
> > >
> > > I wonder if it would be possible instead to always return a negative error
> > > code on error. Returning zero on error is really unconventional and can be
> > > expected to be a source of bugs.
> >
> > Agree, and I did also consider just adding:
> >
> > if (!ret)
> >         return -EINVAL; (or another feasible errno)
> >
> > return ret;
> >
> > at the end of the fwnode_irq_get_byname().
> >
> > However, such a functional change would require auditing the existing
> > callers which I have no time right now.
> 
> Oh. I just did grep the callers. It seems to me that there are only a
> handful of callers in 6.1-rc2. Auditing those does not seem like a big
> task after all. So I guess I can check them if changing the return
> value is preferred.

Yes, please do so.

thanks,

greg k-h