Re: [PATCH 7/8] iommu/arm-smmu-v3: Improve add_device() error handling

[Auger Eric]

Hi Jean,

On 6/10/19 8:47 PM, Jean-Philippe Brucker wrote:
> Let add_device() clean up behind itself. The iommu_bus_init() function
> does call remove_device() on error, but other sites (e.g. of_iommu) do
> not.
> 
> Don't free level-2 stream tables because we'd have to track if we
> allocated each of them or if they are used by other endpoints. It's not
> worth the hassle since they are managed resources.
> 
> Signed-off-by: Jean-Philippe Brucker 
Reviewed-by: Eric Auger 

Thanks

Eric
> ---
>  drivers/iommu/arm-smmu-v3.c | 28 +---
>  1 file changed, 21 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 633d829f246f..972bfb80f964 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -2398,14 +2398,16 @@ static int arm_smmu_add_device(struct device *dev)
>   for (i = 0; i < master->num_sids; i++) {
>   u32 sid = master->sids[i];
>  
> - if (!arm_smmu_sid_in_range(smmu, sid))
> - return -ERANGE;
> + if (!arm_smmu_sid_in_range(smmu, sid)) {
> + ret = -ERANGE;
> + goto err_free_master;
> + }
>  
>   /* Ensure l2 strtab is initialised */
>   if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
>   ret = arm_smmu_init_l2_strtab(smmu, sid);
>   if (ret)
> - return ret;
> + goto err_free_master;
>   }
>   }
>  
> @@ -2419,13 +2421,25 @@ static int arm_smmu_add_device(struct device *dev)
>   if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB))
>   master->ssid_bits = min(master->ssid_bits, 10U);
>  
> + ret = iommu_device_link(&smmu->iommu, dev);
> + if (ret)
> + goto err_free_master;
> +
>   group = iommu_group_get_for_dev(dev);
> - if (!IS_ERR(group)) {
> - iommu_group_put(group);
> - iommu_device_link(&smmu->iommu, dev);
> + if (IS_ERR(group)) {
> + ret = PTR_ERR(group);
> + goto err_unlink;
>   }
>  
> - return PTR_ERR_OR_ZERO(group);
> + iommu_group_put(group);
> + return 0;
> +
> +err_unlink:
> + iommu_device_unlink(&smmu->iommu, dev);
> +err_free_master:
> + kfree(master);
> + fwspec->iommu_priv = NULL;
> + return ret;
>  }
>  
>  static void arm_smmu_remove_device(struct device *dev)
> 

[PATCH 7/8] iommu/arm-smmu-v3: Improve add_device() error handling

[Jean-Philippe Brucker]

Let add_device() clean up behind itself. The iommu_bus_init() function
does call remove_device() on error, but other sites (e.g. of_iommu) do
not.

Don't free level-2 stream tables because we'd have to track if we
allocated each of them or if they are used by other endpoints. It's not
worth the hassle since they are managed resources.

Signed-off-by: Jean-Philippe Brucker 
---
 drivers/iommu/arm-smmu-v3.c | 28 +---
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 633d829f246f..972bfb80f964 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2398,14 +2398,16 @@ static int arm_smmu_add_device(struct device *dev)
for (i = 0; i < master->num_sids; i++) {
u32 sid = master->sids[i];
 
-   if (!arm_smmu_sid_in_range(smmu, sid))
-   return -ERANGE;
+   if (!arm_smmu_sid_in_range(smmu, sid)) {
+   ret = -ERANGE;
+   goto err_free_master;
+   }
 
/* Ensure l2 strtab is initialised */
if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
ret = arm_smmu_init_l2_strtab(smmu, sid);
if (ret)
-   return ret;
+   goto err_free_master;
}
}
 
@@ -2419,13 +2421,25 @@ static int arm_smmu_add_device(struct device *dev)
if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB))
master->ssid_bits = min(master->ssid_bits, 10U);
 
+   ret = iommu_device_link(&smmu->iommu, dev);
+   if (ret)
+   goto err_free_master;
+
group = iommu_group_get_for_dev(dev);
-   if (!IS_ERR(group)) {
-   iommu_group_put(group);
-   iommu_device_link(&smmu->iommu, dev);
+   if (IS_ERR(group)) {
+   ret = PTR_ERR(group);
+   goto err_unlink;
}
 
-   return PTR_ERR_OR_ZERO(group);
+   iommu_group_put(group);
+   return 0;
+
+err_unlink:
+   iommu_device_unlink(&smmu->iommu, dev);
+err_free_master:
+   kfree(master);
+   fwspec->iommu_priv = NULL;
+   return ret;
 }
 
 static void arm_smmu_remove_device(struct device *dev)
-- 
2.21.0