linux-kernel - Re: [PATCH 4/5] thermal/core: Enforce paired .bind/.unbind callbacks

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Message-ID: <CAJZ5v0gXfHQmRGEiHsZRXxTB+=dTLca9fbyQA299gL49ysF6rg@mail.gmail.com>
Date:   Fri, 24 Mar 2023 14:24:12 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Zhang Rui <rui.zhang@...el.com>
Cc:     linux-pm@...r.kernel.org, rafael.j.wysocki@...el.com,
        daniel.lezcano@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] thermal/core: Enforce paired .bind/.unbind callbacks

On Fri, Mar 24, 2023 at 8:08 AM Zhang Rui <rui.zhang@...el.com> wrote:
>
> The .bind/.unbind callbacks are designed to allow the thermal zone
> device to bind to/unbind from a matched cooling device, with thermal
> instances created/deleted.
>
> In this sense, .bind/.unbind callbacks must exist in pairs.
>
> Signed-off-by: Zhang Rui <rui.zhang@...el.com>
> ---
>  drivers/thermal/thermal_core.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 5225d65fb0e0..9c447f22cb39 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1258,6 +1258,11 @@ thermal_zone_device_register_with_trips(const char *type, struct thermal_trip *t
>         if (num_trips > 0 && (!ops->get_trip_type || !ops->get_trip_temp) && !trips)
>                 return ERR_PTR(-EINVAL);
>
> +       if ((ops->bind && !ops->unbind) || (!ops->bind && ops->unbind)) {

This can be written as

        if (!!ops->bind != !!ops->unbind) {

> +               pr_err("Thermal zone device .bind/.unbind not paired\n");

And surely none of the existing drivers do that?  Because it would be
a functional regression if they did.

> +               return ERR_PTR(-EINVAL);
> +       }
> +
>         if (!thermal_class)
>                 return ERR_PTR(-ENODEV);
>
> --