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Message-ID: <7a1cac10-b065-4b4c-b048-10d6b4132f3d@arm.com>
Date: Wed, 5 Mar 2025 08:42:11 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: Anand Moon <linux.amoon@...il.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
On 3/4/25 12:20, Anand Moon wrote:
> 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
[snip]
Right, you're missing the definition at the begging, like:
DEFINE_GUARD(exynos_tmu_data, struct exynos_tmu_data *,
mutex_lock(&_T->lock),
mutex_unlock(&_T->lock))
below the struct exynos_tmu_data definition.
Also, make sure you include the cleanup.h (it might not complain,
but it would be explicit and more clear)
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