Re: [PATCH v2] perf/arm_pmu_platform: Fix an error message related to dev_err_probe() usage

[Christophe JAILLET]

Le 08/08/2022 à 16:57, Robin Murphy a écrit :
> On 2022-08-05 21:55, Christophe JAILLET wrote:
> > dev_err() is a macro that expand dev_fmt, but dev_err_probe() is a
> > function and cannot perform this macro expansion.
> >
> > So hard code the "hw perfevents: " prefix and dd a comment explaining 
> > why.
> >
> > Fixes: 11fa1dc8020a ("perf/arm_pmu_platform: Use dev_err_probe() for 
> > IRQ errors")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> > Untested, but I can't see how it could work.
> >
> > v1 --> v2
> >    - fix a typo in the comment
> > ---
> >   drivers/perf/arm_pmu_platform.c | 7 +++++--
> >   1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/perf/arm_pmu_platform.c 
> > b/drivers/perf/arm_pmu_platform.c
> > index 513de1f54e2d..02cca4b8f0fd 100644
> > --- a/drivers/perf/arm_pmu_platform.c
> > +++ b/drivers/perf/arm_pmu_platform.c
> > @@ -101,8 +101,11 @@ static int pmu_parse_irqs(struct arm_pmu *pmu)
> >       struct device *dev = &pdev->dev;
> >       num_irqs = platform_irq_count(pdev);
> > -    if (num_irqs < 0)
> > -        return dev_err_probe(dev, num_irqs, "unable to count PMU 
> > IRQs\n");
> > +    if (num_irqs < 0) {
> > +        /* dev_err_probe() does not handle dev_fmt, so hard-code the 
> > prefix */
> > +        return dev_err_probe(dev, num_irqs,
> > +                     "hw perfevents: unable to count PMU IRQs\n");
>
> Why not use dev_fmt directly? But even better, is there any practical 
> reason why this couldn't be fixed at the source by indirecting 
> dev_err_probe() through a macro wrapper just like all its friends:
>
> #define dev_err_probe(dev, err, fmt, ...) \
>      _dev_err_probe(dev, err, dev_fmt(fmt), ##__VA_ARGS__)
>
> ?

Looks nice.

I'll propose it in a week or so, unless s.o. does it in the mean-time.

CJ

> Thanks,
> Robin.
>
> > +    }
> >       /*
> >        * In this case we have no idea which CPUs are covered by the PMU.