[PATCH v3 24/31] coresight: Add per-CPU path pointer

[Leo Yan]

On Thu, Oct 02, 2025 at 03:22:17PM +0100, Mike Leach wrote:

[...]

> > +static DEFINE_PER_CPU(struct coresight_path *, csdev_cpu_path);
> 
> This replicates the per-cpu tracer_path variable in coresight-sysfs.c
> - seems there should be a way to combine them.
> This is also set / unset on enable / disable

Good question.

I considered this and piloted change, but I gave up. The main reason is
that coresight-sysfs.c not only maintains paths for CPU bound sources;
it also needs to retrieve the path pointer for uncore sources.
Consolidating all of this would make this series complex.

In next spin, I will try to export a helper, like
coresight_get_path(csdev), to retrieve path pointer for per-CPU source.

[...]

> > +int coresight_enable_path(struct coresight_path *path, enum cs_mode mode,
> > +                         void *sink_data)
> > +{
> > +       int ret;
> > +       struct coresight_device *source;
> > +
> > +       ret = _coresight_enable_path(path, mode, sink_data);
> > +       if (ret)
> > +               return ret;
> > +
> > +       source = coresight_get_source(path);
> > +       if (coresight_is_percpu_source(source))
> > +               per_cpu(csdev_cpu_path, source->cpu) = path;
> 
> 
> why is this in a refactored function for enable() but not disable().
> Seems that the original coresight_enable_path() creates a 'source'
> variable, so just the two lines
> 
> if (coresight_is_percpu_source(source))
>               per_cpu(csdev_cpu_path, source->cpu) = path;

It would be (checking for only success case):

    if (!ret && coresight_is_percpu_source(source))
            per_cpu(csdev_cpu_path, source->cpu) = path;

> added to the original function acheives the same thing with less churn

Okay, will do.

Thanks,
Leo