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Message-Id: <1448009778-10873-1-git-send-email-van.freenix@gmail.com>
Date: Fri, 20 Nov 2015 16:56:18 +0800
From: Freenix <van.freenix@...il.com>
To: will.deacon@....com
Cc: joro@...tes.org, linux-arm-kernel@...ts.infradead.org,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
Peng Fan <van.freenix@...il.com>
Subject: [RFC V4] iommu: arm-smmu: correct group reference count
From: Peng Fan <van.freenix@...il.com>
The basic flow for add a device:
arm_smmu_add_device
|->iommu_group_get_for_dev
|->iommu_group_get
return group; (1)
|->ops->device_group : Init/increase reference count to/by 1.
|->iommu_group_add_device : Increase reference count by 1.
return group (2)
|->return 0;
Since we are adding one device, the flow is (2) and the group reference
count will be increased by 2. So, we need to add iommu_group_put at the
end of arm_smmu_add_device to decrease the count by 1.
Also take the failure path into consideration when fail to add a device.
Signed-off-by: Peng Fan <van.freenix@...il.com>
Cc: Will Deacon <will.deacon@....com>
---
V3 thread: https://lkml.org/lkml/2015/11/9/842
Changes V4:
Follow Will's comments and code diff, add the failure path when failed
to add a device.
V2 thread: https://lkml.org/lkml/2015/11/9/39
Changes V3:
This patch version is wrong to fix the group reference issue.
V1 thread: https://lkml.org/lkml/2015/11/3/304
Changes V2:
I did not see the update about device_group when I worked out V1. So
redo the patch and refine commit msg and rebased to latest linus'
linux master tree.
drivers/iommu/arm-smmu-v3.c | 18 +++++++++++-------
drivers/iommu/arm-smmu.c | 2 ++
2 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 4e5118a..42d30ef 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1804,13 +1804,13 @@ static int arm_smmu_add_device(struct device *dev)
smmu = arm_smmu_get_for_pci_dev(pdev);
if (!smmu) {
ret = -ENOENT;
- goto out_put_group;
+ goto out_remove_dev;
}
smmu_group = kzalloc(sizeof(*smmu_group), GFP_KERNEL);
if (!smmu_group) {
ret = -ENOMEM;
- goto out_put_group;
+ goto out_remove_dev;
}
smmu_group->ste.valid = true;
@@ -1826,20 +1826,20 @@ static int arm_smmu_add_device(struct device *dev)
for (i = 0; i < smmu_group->num_sids; ++i) {
/* If we already know about this SID, then we're done */
if (smmu_group->sids[i] == sid)
- return 0;
+ goto out_put_group;
}
/* Check the SID is in range of the SMMU and our stream table */
if (!arm_smmu_sid_in_range(smmu, sid)) {
ret = -ERANGE;
- goto out_put_group;
+ goto out_remove_dev;
}
/* Ensure l2 strtab is initialised */
if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
ret = arm_smmu_init_l2_strtab(smmu, sid);
if (ret)
- goto out_put_group;
+ goto out_remove_dev;
}
/* Resize the SID array for the group */
@@ -1849,16 +1849,20 @@ static int arm_smmu_add_device(struct device *dev)
if (!sids) {
smmu_group->num_sids--;
ret = -ENOMEM;
- goto out_put_group;
+ goto out_remove_dev;
}
/* Add the new SID */
sids[smmu_group->num_sids - 1] = sid;
smmu_group->sids = sids;
- return 0;
out_put_group:
iommu_group_put(group);
+ return 0;
+
+out_remove_dev:
+ iommu_group_remove_device(dev);
+ iommu_group_put(group);
return ret;
}
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 47dc7a7..af6afce 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1357,6 +1357,8 @@ static int arm_smmu_add_device(struct device *dev)
if (IS_ERR(group))
return PTR_ERR(group);
+ iommu_group_put(group);
+
return 0;
}
--
2.6.2
--
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