linux-kernel - Re: [PATCH v3 4/4] drivers/thermal/exymos: Use guard notation when acquiring mutex

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Message-ID: <CANAwSgTpV_kGFEU-ND0N+OEtT6+j4ceq37xAoLyC7iHPWAuLjg@mail.gmail.com>
Date: Sat, 1 Mar 2025 00:06:10 +0530
From: Anand Moon <linux.amoon@...il.com>
To: Lukasz Luba <lukasz.luba@....com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>, 
	"open list:SAMSUNG THERMAL DRIVER" <linux-samsung-soc@...r.kernel.org>, 
	"open list:SAMSUNG THERMAL DRIVER" <linux-pm@...r.kernel.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	Daniel Lezcano <daniel.lezcano@...aro.org>, open list <linux-kernel@...r.kernel.org>, 
	"moderated list:ARM/SAMSUNG S3C, S5P AND EXYNOS ARM ARCHITECTURES" <linux-arm-kernel@...ts.infradead.org>, Zhang Rui <rui.zhang@...el.com>, 
	Krzysztof Kozlowski <krzk@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH v3 4/4] drivers/thermal/exymos: Use guard notation when
 acquiring mutex

Hi Lukasz,

On Fri, 28 Feb 2025 at 22:58, Lukasz Luba <lukasz.luba@....com> wrote:
>
>
>
> On 2/16/25 19:58, Anand Moon wrote:
> > Using guard notation makes the code more compact and error handling
> > more robust by ensuring that mutexes are released in all code paths
> > when control leaves critical section.
> >
> > Signed-off-by: Anand Moon <linux.amoon@...il.com>
> > ---
> > v3: new patch
> > ---
> >   drivers/thermal/samsung/exynos_tmu.c | 21 +++++++--------------
> >   1 file changed, 7 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> > index fe090c1a93ab..a34ba3858d64 100644
> > --- a/drivers/thermal/samsung/exynos_tmu.c
> > +++ b/drivers/thermal/samsung/exynos_tmu.c
> > @@ -256,7 +256,7 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
> >       unsigned int status;
> >       int ret = 0;
> >
> > -     mutex_lock(&data->lock);
> > +     guard(mutex)(&data->lock);
> >       clk_enable(data->clk);
> >       clk_enable(data->clk_sec);
> >
> > @@ -270,7 +270,6 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
> >
> >       clk_disable(data->clk_sec);
> >       clk_disable(data->clk);
> > -     mutex_unlock(&data->lock);
> >
> >       return ret;
> >   }
> > @@ -292,13 +291,12 @@ static int exynos_thermal_zone_configure(struct platform_device *pdev)
> >               return ret;
> >       }
> >
> > -     mutex_lock(&data->lock);
> > +     guard(mutex)(&data->lock);
> >       clk_enable(data->clk);
> >
> >       data->tmu_set_crit_temp(data, temp / MCELSIUS);
> >
> >       clk_disable(data->clk);
> > -     mutex_unlock(&data->lock);
> >
> >       return 0;
> >   }
> > @@ -325,12 +323,11 @@ static void exynos_tmu_control(struct platform_device *pdev, bool on)
> >   {
> >       struct exynos_tmu_data *data = platform_get_drvdata(pdev);
> >
> > -     mutex_lock(&data->lock);
> > +     guard(mutex)(&data->lock);
> >       clk_enable(data->clk);
> >       data->tmu_control(pdev, on);
> >       data->enabled = on;
> >       clk_disable(data->clk);
> > -     mutex_unlock(&data->lock);
> >   }
> >
> >   static void exynos_tmu_update_bit(struct exynos_tmu_data *data, int reg_off,
> > @@ -645,7 +642,7 @@ static int exynos_get_temp(struct thermal_zone_device *tz, int *temp)
> >                */
> >               return -EAGAIN;
> >
> > -     mutex_lock(&data->lock);
> > +     guard(mutex)(&data->lock);
> >       clk_enable(data->clk);
> >
> >       value = data->tmu_read(data);
> > @@ -655,7 +652,6 @@ static int exynos_get_temp(struct thermal_zone_device *tz, int *temp)
> >               *temp = code_to_temp(data, value) * MCELSIUS;
> >
> >       clk_disable(data->clk);
> > -     mutex_unlock(&data->lock);
> >
> >       return ret;
> >   }
> > @@ -720,11 +716,10 @@ static int exynos_tmu_set_emulation(struct thermal_zone_device *tz, int temp)
> >       if (temp && temp < MCELSIUS)
> >               goto out;
> >
> > -     mutex_lock(&data->lock);
> > +     guard(mutex)(&data->lock);
> >       clk_enable(data->clk);
> >       data->tmu_set_emulation(data, temp);
> >       clk_disable(data->clk);
> > -     mutex_unlock(&data->lock);
> >       return 0;
> >   out:
> >       return ret;
> > @@ -760,14 +755,13 @@ static irqreturn_t exynos_tmu_threaded_irq(int irq, void *id)
> >
> >       thermal_zone_device_update(data->tzd, THERMAL_EVENT_UNSPECIFIED);
> >
> > -     mutex_lock(&data->lock);
> > +     guard(mutex)(&data->lock);
> >       clk_enable(data->clk);
> >
> >       /* TODO: take action based on particular interrupt */
> >       data->tmu_clear_irqs(data);
> >
> >       clk_disable(data->clk);
> > -     mutex_unlock(&data->lock);
> >
> >       return IRQ_HANDLED;
> >   }
> > @@ -987,7 +981,7 @@ static int exynos_set_trips(struct thermal_zone_device *tz, int low, int high)
> >   {
> >       struct exynos_tmu_data *data = thermal_zone_device_priv(tz);
> >
> > -     mutex_lock(&data->lock);
> > +     guard(mutex)(&data->lock);
> >       clk_enable(data->clk);
> >
> >       if (low > INT_MIN)
> > @@ -1000,7 +994,6 @@ static int exynos_set_trips(struct thermal_zone_device *tz, int low, int high)
> >               data->tmu_disable_high(data);
> >
> >       clk_disable(data->clk);
> > -     mutex_unlock(&data->lock);
> >
> >       return 0;
> >   }

Thanks for your review comments.
>
> IMO you should be able to even use something like we have
> core framework:
>
> guard(thermal_zone)(tz);
>
> Your mutex name is simply 'lock' in the struct exynos_tmu_data
> so you should be able to leverage this by:
>
> guard(exynos_tmu_data)(data);
>
> Please try that.

Ok, I will check this

Thanks
-Anand