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

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Message-ID: <CANhJrGPzg9-14OhscgCv6P_9kUG8Nx3mZLEq41aSJ45qh6eaKg@mail.gmail.com>
Date:   Tue, 25 Oct 2022 10:17:21 +0300
From:   Matti Vaittinen <mazziesaccount@...il.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     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>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "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

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.

Yours,
--Matti