[PATCH v2] iommu/arm-smmu-v3: Fix not checking return value about devm_add_action

[PATCH v2] iommu/arm-smmu-v3: Fix not checking return value about devm_add_action

[Tian Tao]

Use devm_add_action_or_reset to avoid the situation where the release
function is not called when devm_add_action returns an error.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
---
v2:
repositioning devm_add_action_or_reset in the function
arm_smmu_setup_msis, and check the return value.
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 2ddf5ec..b4d3b7d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2680,7 +2680,8 @@ static int arm_smmu_cmdq_init(struct arm_smmu_device *smmu)
 		ret = -ENOMEM;
 	} else {
 		cmdq->valid_map = bitmap;
-		devm_add_action(smmu->dev, arm_smmu_cmdq_free_bitmap, bitmap);
+		ret = devm_add_action_or_reset(smmu->dev,
+					       arm_smmu_cmdq_free_bitmap, bitmap);
 	}
 
 	return ret;
@@ -2921,6 +2922,13 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
 		return;
 	}
 
+	/* Add callback to free MSIs on teardown */
+	ret = devm_add_action_or_reset(dev, arm_smmu_free_msis, dev);
+	if (ret) {
+		dev_warn(dev, "failed to add callback to free MSIs on teardown\n");
+		return;
+	}
+
 	for_each_msi_entry(desc, dev) {
 		switch (desc->platform.msi_index) {
 		case EVTQ_MSI_INDEX:
@@ -2936,9 +2944,6 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
 			continue;
 		}
 	}
-
-	/* Add callback to free MSIs on teardown */
-	devm_add_action(dev, arm_smmu_free_msis, dev);
 }
 
 static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
-- 
2.7.4

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Re: [PATCH v2] iommu/arm-smmu-v3: Fix not checking return value about devm_add_action

[Will Deacon]

On Tue, Dec 08, 2020 at 08:15:22PM +0800, Tian Tao wrote:
> Use devm_add_action_or_reset to avoid the situation where the release
> function is not called when devm_add_action returns an error.
> 
> Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
> ---
> v2:
> repositioning devm_add_action_or_reset in the function
> arm_smmu_setup_msis, and check the return value.
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 2ddf5ec..b4d3b7d 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2680,7 +2680,8 @@ static int arm_smmu_cmdq_init(struct arm_smmu_device *smmu)
>  		ret = -ENOMEM;
>  	} else {
>  		cmdq->valid_map = bitmap;
> -		devm_add_action(smmu->dev, arm_smmu_cmdq_free_bitmap, bitmap);
> +		ret = devm_add_action_or_reset(smmu->dev,
> +					       arm_smmu_cmdq_free_bitmap, bitmap);
>  	}
>  
>  	return ret;
> @@ -2921,6 +2922,13 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
>  		return;
>  	}
>  
> +	/* Add callback to free MSIs on teardown */
> +	ret = devm_add_action_or_reset(dev, arm_smmu_free_msis, dev);
> +	if (ret) {
> +		dev_warn(dev, "failed to add callback to free MSIs on teardown\n");
> +		return;

Honestly, wouldn't we just be better leaking memory in this case? Tearing
down the SMMU is a pretty specialist sport _anyway_, but this seems to throw
the baby out with the bath water by failing to initialise because we can't
defer freeing something that we've already allocated. I think we're better
off continuing and trying to get the device up and running.

In fact, the same applies to the cmdq 'valid_map' too -- why do we care?

WIll
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