[PATCH 00/10] iommu: Convert to platform remove callback returning void

[PATCH 00/10] iommu: Convert to platform remove callback returning void

[Uwe Kleine-König]

Hello,

this series adapts the platform drivers below drivers/iommu to use the
.remove_new() callback. Compared to the traditional .remove() callback
.remove_new() returns no value. This is a good thing because the driver core
doesn't (and cannot) cope for errors during remove. The only effect of a
non-zero return value in .remove() is that the driver core emits a warning. The
device is removed anyhow and an early return from .remove() usually yields a
resource leak.

By changing the remove callback to return void driver authors cannot
reasonably assume any more that there is some kind of cleanup later.

After the first patch all drivers return zero unconditionally in their
.remove() callback, then the remaining patches convert to .remove_new()
without side effects.

There is only a single interdependency (namely patch #4 depends on #1).
If there are concerns for individual patches[1], please still apply the
others. Then I'd only care for the actual change requests and don't need
to resend the other unchanged patches at a later point in time.

Thanks
Uwe

[1] I don't expect something more tragic than "You picked the wrong
subject prefix" or similar.

Uwe Kleine-König (10):
  iommu/arm-smmu: Drop if with an always false condition
  iommu/apple-dart: Convert to platform remove callback returning void
  iommu/arm-smmu-v3: Convert to platform remove callback returning void
  iommu/arm-smmu: Convert to platform remove callback returning void
  iommu/ipmmu-vmsa: Convert to platform remove callback returning void
  iommu/msm: Convert to platform remove callback returning void
  iommu/mtk: Convert to platform remove callback returning void
  iommu/mtk_iommu_v1: Convert to platform remove callback returning void
  iommu/omap: Convert to platform remove callback returning void
  iommu/sprd: Convert to platform remove callback returning void

 drivers/iommu/apple-dart.c                  |  6 ++----
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  6 ++----
 drivers/iommu/arm/arm-smmu/arm-smmu.c       | 12 ++----------
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     | 12 ++++--------
 drivers/iommu/ipmmu-vmsa.c                  |  6 ++----
 drivers/iommu/msm_iommu.c                   |  5 ++---
 drivers/iommu/mtk_iommu.c                   |  5 ++---
 drivers/iommu/mtk_iommu_v1.c                |  5 ++---
 drivers/iommu/omap-iommu.c                  |  5 ++---
 drivers/iommu/sprd-iommu.c                  |  6 ++----
 10 files changed, 22 insertions(+), 46 deletions(-)

base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
-- 
2.39.2

[PATCH 07/10] iommu/mtk: 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 (mostly) ignored
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.

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>
---
 drivers/iommu/mtk_iommu.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index d5a4955910ff..bcc7ccdb2d6e 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1316,7 +1316,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int mtk_iommu_remove(struct platform_device *pdev)
+static void mtk_iommu_remove(struct platform_device *pdev)
 {
 	struct mtk_iommu_data *data = platform_get_drvdata(pdev);
 	struct mtk_iommu_bank_data *bank;
@@ -1338,7 +1338,6 @@ static int mtk_iommu_remove(struct platform_device *pdev)
 			continue;
 		devm_free_irq(&pdev->dev, bank->irq, bank);
 	}
-	return 0;
 }
 
 static int __maybe_unused mtk_iommu_runtime_suspend(struct device *dev)
@@ -1595,7 +1594,7 @@ static const struct of_device_id mtk_iommu_of_ids[] = {
 
 static struct platform_driver mtk_iommu_driver = {
 	.probe	= mtk_iommu_probe,
-	.remove	= mtk_iommu_remove,
+	.remove_new = mtk_iommu_remove,
 	.driver	= {
 		.name = "mtk-iommu",
 		.of_match_table = mtk_iommu_of_ids,
-- 
2.39.2

[PATCH 08/10] iommu/mtk_iommu_v1: 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 (mostly) ignored
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.

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>
---
 drivers/iommu/mtk_iommu_v1.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 43e4c8f89e23..8a0a5e5d049f 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -703,7 +703,7 @@ static int mtk_iommu_v1_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int mtk_iommu_v1_remove(struct platform_device *pdev)
+static void mtk_iommu_v1_remove(struct platform_device *pdev)
 {
 	struct mtk_iommu_v1_data *data = platform_get_drvdata(pdev);
 
@@ -713,7 +713,6 @@ static int mtk_iommu_v1_remove(struct platform_device *pdev)
 	clk_disable_unprepare(data->bclk);
 	devm_free_irq(&pdev->dev, data->irq, data);
 	component_master_del(&pdev->dev, &mtk_iommu_v1_com_ops);
-	return 0;
 }
 
 static int __maybe_unused mtk_iommu_v1_suspend(struct device *dev)
@@ -752,7 +751,7 @@ static const struct dev_pm_ops mtk_iommu_v1_pm_ops = {
 
 static struct platform_driver mtk_iommu_v1_driver = {
 	.probe	= mtk_iommu_v1_probe,
-	.remove	= mtk_iommu_v1_remove,
+	.remove_new = mtk_iommu_v1_remove,
 	.driver	= {
 		.name = "mtk-iommu-v1",
 		.of_match_table = mtk_iommu_v1_of_ids,
-- 
2.39.2

Re: [PATCH 08/10] iommu/mtk_iommu_v1: Convert to platform remove callback returning void

[AngeloGioacchino Del Regno]

Il 21/03/23 09:41, Uwe Kleine-König ha scritto:
> 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 (mostly) ignored
> 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.
> 
> 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>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Re: [PATCH 07/10] iommu/mtk: Convert to platform remove callback returning void

[AngeloGioacchino Del Regno]

Il 21/03/23 09:41, Uwe Kleine-König ha scritto:
> 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 (mostly) ignored
> 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.
> 
> 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>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Re: [PATCH 00/10] iommu: Convert to platform remove callback returning void

[Joerg Roedel]

On Tue, Mar 21, 2023 at 09:41:15AM +0100, Uwe Kleine-König wrote:
> Uwe Kleine-König (10):
>   iommu/arm-smmu: Drop if with an always false condition
>   iommu/apple-dart: Convert to platform remove callback returning void
>   iommu/arm-smmu-v3: Convert to platform remove callback returning void
>   iommu/arm-smmu: Convert to platform remove callback returning void
>   iommu/ipmmu-vmsa: Convert to platform remove callback returning void
>   iommu/msm: Convert to platform remove callback returning void
>   iommu/mtk: Convert to platform remove callback returning void
>   iommu/mtk_iommu_v1: Convert to platform remove callback returning void
>   iommu/omap: Convert to platform remove callback returning void
>   iommu/sprd: Convert to platform remove callback returning void

Applied, thanks.