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Message-ID: <CANAwSgSWf_YxSi-pzWPaRoiJx7RLrWUz+HTWx5hf+E2x1ZGmoQ@mail.gmail.com>
Date: Tue, 4 Mar 2025 17:50:01 +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 Sat, 1 Mar 2025 at 00:06, Anand Moon <linux.amoon@...il.com> wrote:
>
> 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);
> >
If I introduce the guard it creates a compilation error
amoon@...nd-m920q:~/mainline/linux-exynos-6.y-devel$ vi
drivers/thermal/samsung/exynos_tmu.c +306
amoon@...nd-m920q:~/mainline/linux-exynos-6.y-devel$ make -j$(nproc)
ARCH=arm CROSS_COMPILE=arm-none-eabi- LOCALVERSION=-u3ml dtbs zImage
modules
CALL scripts/checksyscalls.sh
CHK kernel/kheaders_data.tar.xz
CC drivers/thermal/samsung/exynos_tmu.o
CC [M] drivers/md/raid10.o
In file included from ./include/linux/irqflags.h:17,
from ./arch/arm/include/asm/bitops.h:28,
from ./include/linux/bitops.h:68,
from ./include/linux/kernel.h:23,
from ./include/linux/clk.h:13,
from drivers/thermal/samsung/exynos_tmu.c:14:
drivers/thermal/samsung/exynos_tmu.c: In function 'exynos_tmu_update_bit':
./include/linux/cleanup.h:258:9: error: unknown type name
'class_exynos_tmu_data_t'
258 | class_##_name##_t var
__cleanup(class_##_name##_destructor) = \
| ^~~~~~
./include/linux/cleanup.h:309:9: note: in expansion of macro 'CLASS'
309 | CLASS(_name, __UNIQUE_ID(guard))
| ^~~~~
drivers/thermal/samsung/exynos_tmu.c:338:9: note: in expansion of macro 'guard'
338 | guard(exynos_tmu_data)(data);
| ^~~~~
drivers/thermal/samsung/exynos_tmu.c:338:9: error: cleanup argument
not a function
CC [M] drivers/md/raid5.o
./include/linux/cleanup.h:259:17: error: implicit declaration of
function 'class_exynos_tmu_data_constructor'
[-Wimplicit-function-declaration]
259 | class_##_name##_constructor
| ^~~~~~
./include/linux/cleanup.h:309:9: note: in expansion of macro 'CLASS'
309 | CLASS(_name, __UNIQUE_ID(guard))
| ^~~~~
drivers/thermal/samsung/exynos_tmu.c:338:9: note: in expansion of macro 'guard'
338 | guard(exynos_tmu_data)(data);
| ^~~~~
./include/linux/compiler.h:166:45: warning: unused variable
'__UNIQUE_ID_guard572' [-Wunused-variable]
166 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_,
prefix), __COUNTER__)
| ^~~~~~~~~~~~
./include/linux/cleanup.h:258:27: note: in definition of macro 'CLASS'
258 | class_##_name##_t var
__cleanup(class_##_name##_destructor) = \
| ^~~
././include/linux/compiler_types.h:84:22: note: in expansion of macro '___PASTE'
84 | #define __PASTE(a,b) ___PASTE(a,b)
| ^~~~~~~~
./include/linux/compiler.h:166:29: note: in expansion of macro '__PASTE'
166 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_,
prefix), __COUNTER__)
| ^~~~~~~
././include/linux/compiler_types.h:84:22: note: in expansion of macro '___PASTE'
84 | #define __PASTE(a,b) ___PASTE(a,b)
| ^~~~~~~~
./include/linux/compiler.h:166:37: note: in expansion of macro '__PASTE'
166 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_,
prefix), __COUNTER__)
| ^~~~~~~
./include/linux/cleanup.h:309:22: note: in expansion of macro '__UNIQUE_ID'
309 | CLASS(_name, __UNIQUE_ID(guard))
| ^~~~~~~~~~~
drivers/thermal/samsung/exynos_tmu.c:338:9: note: in expansion of macro 'guard'
338 | guard(exynos_tmu_data)(data);
Thanks
-Anand
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