Re: [PATCH 01/32] perf: Allow a PMU to have a parent

[Yicong Yang]

On 2023/4/4 21:41, Jonathan Cameron wrote:
> Some PMUs have well defined parents such as PCI devices.
> As the device_initialize() and device_add() are all within
> pmu_dev_alloc() which is called from perf_pmu_register()
> there is no opportunity to set the parent from within a driver.
> 
> Add a struct device *parent field to struct pmu and use that
> to set the parent.
> 
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> 
> ---
> Previously posted in CPMU series hence the change log.
> v3: No change
> ---
>  include/linux/perf_event.h | 1 +
>  kernel/events/core.c       | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index d5628a7b5eaa..b99db1eda72c 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -303,6 +303,7 @@ struct pmu {
>  
>  	struct module			*module;
>  	struct device			*dev;
> +	struct device			*parent;
>  	const struct attribute_group	**attr_groups;
>  	const struct attribute_group	**attr_update;
>  	const char			*name;
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index fb3e436bcd4a..a84c282221f2 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -11367,6 +11367,7 @@ static int pmu_dev_alloc(struct pmu *pmu)
>  
>  	dev_set_drvdata(pmu->dev, pmu);
>  	pmu->dev->bus = &pmu_bus;
> +	pmu->dev->parent = pmu->parent;

If there's no parent assigned, is it ok to add some check here? Then we can find it earlier
maybe at develop stage.

Thanks.

>  	pmu->dev->release = pmu_dev_release;
>  
>  	ret = dev_set_name(pmu->dev, "%s", pmu->name);
>