Re: [PATCH 2/4] thermal/drivers/exynos: fix set_trip_temp() deadlock

From: Johan Hovold <johan@kernel.org>
To: Johan Hovold <johan+linaro@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Amit Kucheria <amitk@kernel.org>,
	Thara Gopinath <thara.gopinath@gmail.com>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Zhang Rui <rui.zhang@intel.com>,
	Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	linux-pm@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-tegra@vger.kernel.org
Subject: Re: [PATCH 2/4] thermal/drivers/exynos: fix set_trip_temp() deadlock
Date: Wed, 14 Dec 2022 15:45:57 +0100	[thread overview]
Message-ID: <Y5nhpfAislGiIQOU@hovoldconsulting.com> (raw)
In-Reply-To: <20221214131617.2447-3-johan+linaro@kernel.org>

On Wed, Dec 14, 2022 at 02:16:15PM +0100, Johan Hovold wrote:
> The set_trip_temp() callback is used when changing the trip temperature
> through sysfs. As it is called with the thermal-zone-device lock held
> it must not use thermal_zone_get_trip() directly or it will deadlock.
> 
> Fixes: 169865e317f2 ("thermal/drivers/exynos: Use generic thermal_zone_get_trip() function")
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/thermal/samsung/exynos_tmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> index 37465af59262..cf9028f80415 100644
> --- a/drivers/thermal/samsung/exynos_tmu.c
> +++ b/drivers/thermal/samsung/exynos_tmu.c
> @@ -354,7 +354,7 @@ static void exynos4210_tmu_set_trip_temp(struct exynos_tmu_data *data,
>  	struct thermal_trip trip;
>  	u8 ref, th_code;
>  
> -	if (thermal_zone_get_trip(data->tzd, 0, &trip))
> +	if (__thermal_zone_get_trip(data->tzd, 0, &trip))
>  		return;
>  
>  	ref = trip.temperature / MCELSIUS;

As Daniel noted, this patch is not correct as this function is not
actually a thermal_zone_device_ops::set_trip_temp callback.

Please drop this one.

Johan