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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Fri, 11 Aug 2023 18:55:19 +0200
Message-ID: <CAJZ5v0jgvfzN+Ug9G_gLV=NXLvfmuC98XzjLes709g2uypQ5nA@mail.gmail.com>
Subject: Re: [PATCH] thermal: intel: intel_soc_dts_iosf: Fix thermal_zone removal
To:     Zhang Rui <rui.zhang@intel.com>
Cc:     rafael.j.wysocki@intel.com, daniel.lezcano@linaro.or,
        srinivas.pandruvada@intel.com, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org
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On Fri, Aug 11, 2023 at 10:45 AM Zhang Rui <rui.zhang@intel.com> wrote:
>
> All of the existing callers of remove_dts_thermal_zone() pass a valid
> pointer as the argument, so checking for the NULL pointer is redundant.

True.

> Plus, when calling remove_dts_thermal_zone() from
> intel_soc_dts_iosf_init(), it is possible that
> 1. dts->tzone is an error pointer, when the sensor fails to be
>    registered as a valid thermal zone
> 2. dts->tzone is unregistered in add_dts_thermal_zone(), when some
>    failure occurs after thermal zone registered
> In both cases, there is no need to unregister dts->tzone in
> remove_dts_thermal_zone().
>
> Clear dst->tzone when add_dts_thermal_zone() fails. And do thermal zone
> removal in remove_dts_thermal_zone() only when dts->tzone is set.

Well, I'm not sure.

thermal_zone_device_unregister() will do nothing if the thermal zone
is not really registered AFAICS and it is prudent to restore
SOC_DTS_OFFSET_ENABLE on failure IMO.


> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
>  drivers/thermal/intel/intel_soc_dts_iosf.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/intel/intel_soc_dts_iosf.c b/drivers/thermal/intel/intel_soc_dts_iosf.c
> index 7a66d0f077b0..c5203ba8f0b9 100644
> --- a/drivers/thermal/intel/intel_soc_dts_iosf.c
> +++ b/drivers/thermal/intel/intel_soc_dts_iosf.c
> @@ -212,7 +212,7 @@ static int soc_dts_enable(int id)
>
>  static void remove_dts_thermal_zone(struct intel_soc_dts_sensor_entry *dts)
>  {
> -       if (dts) {
> +       if (dts->tzone) {
>                 iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE,
>                                SOC_DTS_OFFSET_ENABLE, dts->store_status);
>                 thermal_zone_device_unregister(dts->tzone);
> @@ -277,6 +277,7 @@ static int add_dts_thermal_zone(int id, struct intel_soc_dts_sensor_entry *dts,
>  err_enable:
>         thermal_zone_device_unregister(dts->tzone);
>  err_ret:
> +       dts->tzone = NULL;
>         return ret;
>  }
>
> --
> 2.34.1
>