linux-kernel - Re: [PATCH] base: fix a missing check of clk

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Message-ID: <CAJZ5v0iJCaCju7sgCF9u7PYxmHF0jQDy95_QEVt8q+R2NX5zAA@mail.gmail.com>
Date:   Tue, 1 Jan 2019 22:05:39 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Pavel Machek <pavel@....cz>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>, kjlu@....edu,
        pakki001@....edu, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] base: fix a missing check of clk_prepare

On Tue, Jan 1, 2019 at 9:21 PM Pavel Machek <pavel@....cz> wrote:
>
> On Tue 2019-01-01 21:13:01, Rafael J. Wysocki wrote:
> > On Mon, Dec 31, 2018 at 6:25 PM Pavel Machek <pavel@....cz> wrote:
> > >
> > > On Wed 2018-12-26 10:37:54, Rafael J. Wysocki wrote:
> > > > On Wed, Dec 26, 2018 at 3:47 AM Kangjie Lu <kjlu@....edu> wrote:
> > > > >
> > > > > clk_prepare() could fail, so let's check its status, and if it fails,
> > > > > issue an error message.
> > > > >
> > > > > Signed-off-by: Kangjie Lu <kjlu@....edu>
> > > > > ---
> > > > >  drivers/base/power/clock_ops.c | 4 +++-
> > > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
> > > > > index 5a42ae4078c2..cb6144fb24e2 100644
> > > > > --- a/drivers/base/power/clock_ops.c
> > > > > +++ b/drivers/base/power/clock_ops.c
> > > > > @@ -65,7 +65,9 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
> > > > >         if (IS_ERR(ce->clk)) {
> > > > >                 ce->status = PCE_STATUS_ERROR;
> > > > >         } else {
> > > > > -               clk_prepare(ce->clk);
> > > > > +               if (clk_prepare(ce->clk))
> > > > > +                       dev_err(dev, "clk_prepare failed.\n");
> > > >
> > > > I'm not sure that this is useful.  The code continues regardless of
> > > > the error anyway and it should at least set ce->status to
> > > > PCE_STATUS_ERROR in the failing case.
> > >
> > > Maybe this is not complete fix, but dev_err() is preferable to silent
> > > failure.
> >
> > Preferable to you I suppose?
>
> Preferable to the poor person trying to figure out why his machine
> does not work?

Not really, unless that person knows what the message means.

Honestly, what would you do if you saw that message?