* [PATCH] media: rc: remove unneeded mutex in rc_register_device
@ 2016-03-16 18:53 Heiner Kallweit
2016-03-16 19:33 ` Vladimir Zapolskiy
0 siblings, 1 reply; 3+ messages in thread
From: Heiner Kallweit @ 2016-03-16 18:53 UTC (permalink / raw)
To: Mauro Carvalho Chehab; +Cc: linux-media
Access to dev->initialized is atomic, therefore we don't have to
protect it with a mutex.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
drivers/media/rc/rc-main.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
index 4e9bbe7..68541b1 100644
--- a/drivers/media/rc/rc-main.c
+++ b/drivers/media/rc/rc-main.c
@@ -1492,9 +1492,7 @@ int rc_register_device(struct rc_dev *dev)
}
/* Allow the RC sysfs nodes to be accessible */
- mutex_lock(&dev->lock);
atomic_set(&dev->initialized, 1);
- mutex_unlock(&dev->lock);
IR_dprintk(1, "Registered rc%u (driver: %s, remote: %s, mode %s)\n",
dev->minor,
--
2.7.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] media: rc: remove unneeded mutex in rc_register_device
2016-03-16 18:53 [PATCH] media: rc: remove unneeded mutex in rc_register_device Heiner Kallweit
@ 2016-03-16 19:33 ` Vladimir Zapolskiy
2016-03-16 21:24 ` Heiner Kallweit
0 siblings, 1 reply; 3+ messages in thread
From: Vladimir Zapolskiy @ 2016-03-16 19:33 UTC (permalink / raw)
To: Heiner Kallweit, Mauro Carvalho Chehab; +Cc: linux-media
On 16.03.2016 20:53, Heiner Kallweit wrote:
> Access to dev->initialized is atomic, therefore we don't have to
> protect it with a mutex.
Mutexes are used to split the code to mutually exclusive execution blocks,
so not arguing about the apparently correct change itself I want to
emphasize that the given explanation of the change in the commit message is
wrong. Atomic access does not cancel a specific care about execution
ordering.
Indirectly it applies to ("rc-core: allow calling rc_open with device not
initialized"), where "initialized" bool property was changed to atomic_t
type --- this (sub-)change is just useless.
Please grasp the topic and reword the commit message.
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> drivers/media/rc/rc-main.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
> index 4e9bbe7..68541b1 100644
> --- a/drivers/media/rc/rc-main.c
> +++ b/drivers/media/rc/rc-main.c
> @@ -1492,9 +1492,7 @@ int rc_register_device(struct rc_dev *dev)
> }
>
> /* Allow the RC sysfs nodes to be accessible */
> - mutex_lock(&dev->lock);
> atomic_set(&dev->initialized, 1);
> - mutex_unlock(&dev->lock);
>
> IR_dprintk(1, "Registered rc%u (driver: %s, remote: %s, mode %s)\n",
> dev->minor,
>
--
With best wishes,
Vladimir
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] media: rc: remove unneeded mutex in rc_register_device
2016-03-16 19:33 ` Vladimir Zapolskiy
@ 2016-03-16 21:24 ` Heiner Kallweit
0 siblings, 0 replies; 3+ messages in thread
From: Heiner Kallweit @ 2016-03-16 21:24 UTC (permalink / raw)
To: Vladimir Zapolskiy, Mauro Carvalho Chehab; +Cc: linux-media
Am 16.03.2016 um 20:33 schrieb Vladimir Zapolskiy:
> On 16.03.2016 20:53, Heiner Kallweit wrote:
>> Access to dev->initialized is atomic, therefore we don't have to
>> protect it with a mutex.
>
> Mutexes are used to split the code to mutually exclusive execution blocks,
> so not arguing about the apparently correct change itself I want to
> emphasize that the given explanation of the change in the commit message is
> wrong. Atomic access does not cancel a specific care about execution
> ordering.
>
> Indirectly it applies to ("rc-core: allow calling rc_open with device not
> initialized"), where "initialized" bool property was changed to atomic_t
> type --- this (sub-)change is just useless.
>
> Please grasp the topic and reword the commit message.
>
Thanks for the hint, you're right.
Will change the commit message and send a v2.
Regards, Heiner
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> drivers/media/rc/rc-main.c | 2 --
>> 1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
>> index 4e9bbe7..68541b1 100644
>> --- a/drivers/media/rc/rc-main.c
>> +++ b/drivers/media/rc/rc-main.c
>> @@ -1492,9 +1492,7 @@ int rc_register_device(struct rc_dev *dev)
>> }
>>
>> /* Allow the RC sysfs nodes to be accessible */
>> - mutex_lock(&dev->lock);
>> atomic_set(&dev->initialized, 1);
>> - mutex_unlock(&dev->lock);
>>
>> IR_dprintk(1, "Registered rc%u (driver: %s, remote: %s, mode %s)\n",
>> dev->minor,
>>
>
> --
> With best wishes,
> Vladimir
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-03-16 18:53 [PATCH] media: rc: remove unneeded mutex in rc_register_device Heiner Kallweit
2016-03-16 19:33 ` Vladimir Zapolskiy
2016-03-16 21:24 ` Heiner Kallweit
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