* [PATCH] counter/ftm-quaddec: Use device-managed registration API
@ 2019-07-25 8:54 Chuhong Yuan
2019-07-25 11:31 ` Patrick Havelange
0 siblings, 1 reply; 2+ messages in thread
From: Chuhong Yuan @ 2019-07-25 8:54 UTC (permalink / raw)
Cc: Patrick Havelange, William Breathitt Gray, linux-iio,
linux-kernel, Chuhong Yuan
Make use of devm_counter_register.
Then we can remove redundant unregistration API
usage to make code simpler.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
drivers/counter/ftm-quaddec.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/counter/ftm-quaddec.c b/drivers/counter/ftm-quaddec.c
index 68a9b7393457..bccbca8681b6 100644
--- a/drivers/counter/ftm-quaddec.c
+++ b/drivers/counter/ftm-quaddec.c
@@ -317,7 +317,7 @@ static int ftm_quaddec_probe(struct platform_device *pdev)
ftm_quaddec_init(ftm);
- ret = counter_register(&ftm->counter);
+ ret = devm_counter_register(&pdev->dev, &ftm->counter);
if (ret)
ftm_quaddec_disable(ftm);
@@ -328,8 +328,6 @@ static int ftm_quaddec_remove(struct platform_device *pdev)
{
struct ftm_quaddec *ftm = platform_get_drvdata(pdev);
- counter_unregister(&ftm->counter);
-
ftm_quaddec_disable(ftm);
return 0;
--
2.20.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] counter/ftm-quaddec: Use device-managed registration API
2019-07-25 8:54 [PATCH] counter/ftm-quaddec: Use device-managed registration API Chuhong Yuan
@ 2019-07-25 11:31 ` Patrick Havelange
0 siblings, 0 replies; 2+ messages in thread
From: Patrick Havelange @ 2019-07-25 11:31 UTC (permalink / raw)
To: Chuhong Yuan; +Cc: William Breathitt Gray, linux-iio, linux-kernel
Hello,
Comments inline
On Thu, Jul 25, 2019 at 10:55 AM Chuhong Yuan <hslester96@gmail.com> wrote:
>
> Make use of devm_counter_register.
> Then we can remove redundant unregistration API
> usage to make code simpler.
>
> Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> ---
> drivers/counter/ftm-quaddec.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/counter/ftm-quaddec.c b/drivers/counter/ftm-quaddec.c
> index 68a9b7393457..bccbca8681b6 100644
> --- a/drivers/counter/ftm-quaddec.c
> +++ b/drivers/counter/ftm-quaddec.c
> @@ -317,7 +317,7 @@ static int ftm_quaddec_probe(struct platform_device *pdev)
>
> ftm_quaddec_init(ftm);
>
> - ret = counter_register(&ftm->counter);
> + ret = devm_counter_register(&pdev->dev, &ftm->counter);
> if (ret)
> ftm_quaddec_disable(ftm);
>
> @@ -328,8 +328,6 @@ static int ftm_quaddec_remove(struct platform_device *pdev)
> {
> struct ftm_quaddec *ftm = platform_get_drvdata(pdev);
>
> - counter_unregister(&ftm->counter);
> -
The orders of (de)initialization should be kept symmetrical.
In this case, now that counter_unregister() will be called via devm,
it will be executed after ftm_quaddec_remove()
This introduces a race condition where the ftm-quaddec is disabled but
the counter entry itself is not.
Somebody else (William?) should confirm this.
> ftm_quaddec_disable(ftm);
>
> return 0;
> --
> 2.20.1
>
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2019-07-25 11:31 ` Patrick Havelange
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