[PATCH 1/2] ALSA: pcmtest: Convert to platform remove callback returning void

[PATCH 1/2] ALSA: pcmtest: Convert to platform remove callback returning void

[Uwe Kleine-König]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new() which already returns void. Eventually after all drivers
are converted, .remove_new() is renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 sound/drivers/pcmtest.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/sound/drivers/pcmtest.c b/sound/drivers/pcmtest.c
index 2ae912a64d16..1fff85feaf82 100644
--- a/sound/drivers/pcmtest.c
+++ b/sound/drivers/pcmtest.c
@@ -576,10 +576,9 @@ static int pcmtst_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static int pdev_remove(struct platform_device *dev)
+static void pdev_remove(struct platform_device *dev)
 {
 	snd_pcmtst_free(pcmtst);
-	return 0;
 }
 
 static struct platform_device pcmtst_pdev = {
@@ -589,7 +588,7 @@ static struct platform_device pcmtst_pdev = {
 
 static struct platform_driver pcmtst_pdrv = {
 	.probe =	pcmtst_probe,
-	.remove =	pdev_remove,
+	.remove_new =	pdev_remove,
 	.driver =	{
 		.name = "pcmtest",
 	},

base-commit: 5133c9e51de41bfa902153888e11add3342ede18
-- 
2.39.2

[PATCH 2/2] ALSA: pcmtest: Don't use static storage to track per device data

[Uwe Kleine-König]

While there is probably only ever a single instance of such a pcmtst
device, it's still bad style to use a static variable to store per
device data. Make use of platform_get_drvdata() and
platform_set_drvdata() which fixes a data corruption if there should be
two or more such devices (or this driver is used as a template for
another driver).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 sound/drivers/pcmtest.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/sound/drivers/pcmtest.c b/sound/drivers/pcmtest.c
index 1fff85feaf82..291e7fe47893 100644
--- a/sound/drivers/pcmtest.c
+++ b/sound/drivers/pcmtest.c
@@ -110,8 +110,6 @@ struct pcmtst_buf_iter {
 	struct timer_list timer_instance;
 };
 
-static struct pcmtst *pcmtst;
-
 static struct snd_pcm_hardware snd_pcmtst_hw = {
 	.info = (SNDRV_PCM_INFO_INTERLEAVED |
 		 SNDRV_PCM_INFO_BLOCK_TRANSFER |
@@ -552,6 +550,7 @@ static int snd_pcmtst_create(struct snd_card *card, struct platform_device *pdev
 static int pcmtst_probe(struct platform_device *pdev)
 {
 	struct snd_card *card;
+	struct pcmtst *pcmtst;
 	int err;
 
 	err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
@@ -573,11 +572,15 @@ static int pcmtst_probe(struct platform_device *pdev)
 	if (err < 0)
 		return err;
 
+	platform_set_drvdata(pdev, pcmtst);
+
 	return 0;
 }
 
-static void pdev_remove(struct platform_device *dev)
+static void pdev_remove(struct platform_device *pdev)
 {
+	struct pcmtst *pcmtst = platform_get_drvdata(pdev);
+
 	snd_pcmtst_free(pcmtst);
 }
 
-- 
2.39.2

Re: [PATCH 1/2] ALSA: pcmtest: Convert to platform remove callback returning void

[Ivan Orlov]

On 7/7/23 11:50, Uwe Kleine-König wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new() which already returns void. Eventually after all drivers
> are converted, .remove_new() is renamed to .remove().
> 
> Trivially convert this driver from always returning zero in the remove
> callback to the void returning variant.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>   sound/drivers/pcmtest.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/drivers/pcmtest.c b/sound/drivers/pcmtest.c
> index 2ae912a64d16..1fff85feaf82 100644
> --- a/sound/drivers/pcmtest.c
> +++ b/sound/drivers/pcmtest.c
> @@ -576,10 +576,9 @@ static int pcmtst_probe(struct platform_device *pdev)
>   	return 0;
>   }
>   
> -static int pdev_remove(struct platform_device *dev)
> +static void pdev_remove(struct platform_device *dev)
>   {
>   	snd_pcmtst_free(pcmtst);
> -	return 0;
>   }
>   
>   static struct platform_device pcmtst_pdev = {
> @@ -589,7 +588,7 @@ static struct platform_device pcmtst_pdev = {
>   
>   static struct platform_driver pcmtst_pdrv = {
>   	.probe =	pcmtst_probe,
> -	.remove =	pdev_remove,
> +	.remove_new =	pdev_remove,
>   	.driver =	{
>   		.name = "pcmtest",
>   	},
> 
> base-commit: 5133c9e51de41bfa902153888e11add3342ede18

Looks good to me, thanks!

Re: [PATCH 2/2] ALSA: pcmtest: Don't use static storage to track per device data

[Ivan Orlov]

On 7/7/23 11:50, Uwe Kleine-König wrote:
> While there is probably only ever a single instance of such a pcmtst
> device, it's still bad style to use a static variable to store per
> device data. Make use of platform_get_drvdata() and
> platform_set_drvdata() which fixes a data corruption if there should be
> two or more such devices (or this driver is used as a template for
> another driver).
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>   sound/drivers/pcmtest.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/drivers/pcmtest.c b/sound/drivers/pcmtest.c
> index 1fff85feaf82..291e7fe47893 100644
> --- a/sound/drivers/pcmtest.c
> +++ b/sound/drivers/pcmtest.c
> @@ -110,8 +110,6 @@ struct pcmtst_buf_iter {
>   	struct timer_list timer_instance;
>   };
>   
> -static struct pcmtst *pcmtst;
> -
>   static struct snd_pcm_hardware snd_pcmtst_hw = {
>   	.info = (SNDRV_PCM_INFO_INTERLEAVED |
>   		 SNDRV_PCM_INFO_BLOCK_TRANSFER |
> @@ -552,6 +550,7 @@ static int snd_pcmtst_create(struct snd_card *card, struct platform_device *pdev
>   static int pcmtst_probe(struct platform_device *pdev)
>   {
>   	struct snd_card *card;
> +	struct pcmtst *pcmtst;
>   	int err;
>   
>   	err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> @@ -573,11 +572,15 @@ static int pcmtst_probe(struct platform_device *pdev)
>   	if (err < 0)
>   		return err;
>   
> +	platform_set_drvdata(pdev, pcmtst);
> +
>   	return 0;
>   }
>   
> -static void pdev_remove(struct platform_device *dev)
> +static void pdev_remove(struct platform_device *pdev)
>   {
> +	struct pcmtst *pcmtst = platform_get_drvdata(pdev);
> +
>   	snd_pcmtst_free(pcmtst);
>   }
>   

Also looks good.

Acked-by: Ivan Orlov <ivan.orlov0322@gmail.com>

Re: [PATCH 1/2] ALSA: pcmtest: Convert to platform remove callback returning void

[Ivan Orlov]

On 7/7/23 11:50, Uwe Kleine-König wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new() which already returns void. Eventually after all drivers
> are converted, .remove_new() is renamed to .remove().
> 
> Trivially convert this driver from always returning zero in the remove
> callback to the void returning variant.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>   sound/drivers/pcmtest.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/drivers/pcmtest.c b/sound/drivers/pcmtest.c
> index 2ae912a64d16..1fff85feaf82 100644
> --- a/sound/drivers/pcmtest.c
> +++ b/sound/drivers/pcmtest.c
> @@ -576,10 +576,9 @@ static int pcmtst_probe(struct platform_device *pdev)
>   	return 0;
>   }
>   
> -static int pdev_remove(struct platform_device *dev)
> +static void pdev_remove(struct platform_device *dev)
>   {
>   	snd_pcmtst_free(pcmtst);
> -	return 0;
>   }
>   
>   static struct platform_device pcmtst_pdev = {
> @@ -589,7 +588,7 @@ static struct platform_device pcmtst_pdev = {
>   
>   static struct platform_driver pcmtst_pdrv = {
>   	.probe =	pcmtst_probe,
> -	.remove =	pdev_remove,
> +	.remove_new =	pdev_remove,
>   	.driver =	{
>   		.name = "pcmtest",
>   	},
> 
> base-commit: 5133c9e51de41bfa902153888e11add3342ede18

Acked-by: Ivan Orlov <ivan.orlov0322@gmail.com>

Re: [PATCH 1/2] ALSA: pcmtest: Convert to platform remove callback returning void

[Takashi Iwai]

On Fri, 07 Jul 2023 09:50:57 +0200,
Uwe Kleine-König wrote:
> 
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new() which already returns void. Eventually after all drivers
> are converted, .remove_new() is renamed to .remove().
> 
> Trivially convert this driver from always returning zero in the remove
> callback to the void returning variant.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Applied both patches now.  Thanks!


Takashi