Re: [PATCH v1] cpufreq: Avoid creating sysfs link for offline CPUs

[Zihuan Zhang]

在 2025/7/21 23:51, Rafael J. Wysocki 写道:
> On Mon, Jul 21, 2025 at 5:37 PM Zihuan Zhang <zzhwaxy.kernel@xxxxxxxxx> wrote:
> > Currently, cpufreq_add_dev() attempts to create a sysfs link
> > even when the target CPU is offline. Although guarded by a NULL
> > check on cpufreq_policy, this behavior is not strictly correct,
> > since offline CPUs shouldn't have their sysfs interface created.
> Why?


Thanks for the comment.

The idea was to avoid unnecessary sysfs operations for CPUs that are 
offline, even though the existing checks make it safe. But I understand 
it's not strictly needed — I'm fine with dropping it.

> > This patch cleans up the logic to only add the sysfs link
> > when the CPU is online and cpufreq policy is properly initialized.
> I don't really think that this change is necessary.  Thanks!
>
> > Signed-off-by: Zihuan Zhang <zzhwaxy.kernel@xxxxxxxxx>
> > ---
> >   drivers/cpufreq/cpufreq.c | 10 +++++-----
> >   1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index d7426e1d8bdd..0a77892d366c 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -1660,12 +1660,12 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
> >                  ret = cpufreq_online(cpu);
> >                  if (ret)
> >                          return ret;
> > -       }
> >
> > -       /* Create sysfs link on CPU registration */
> > -       policy = per_cpu(cpufreq_cpu_data, cpu);
> > -       if (policy)
> > -               add_cpu_dev_symlink(policy, cpu, dev);
> > +               /* Create sysfs link on CPU registration */
> > +               policy = per_cpu(cpufreq_cpu_data, cpu);
> > +               if (policy)
> > +                       add_cpu_dev_symlink(policy, cpu, dev);
> > +       }
> >
> >          return 0;
> >   }
> > --