[PATCH v9 04/12] iommu/arm-smmu-v3: Destroy vmid_map ida via devres

[Nicolin Chen]

The vmid_map ida is only destroyed in arm_smmu_device_remove(), which does
not run when the probe fails. This is currently harmless, as the ida stays
empty until the first S2 domain allocation, which can only happen after a
successful probe.

An upcoming change will start reserving the crashed kernel's VMIDs in this
ida, at the probe time of a kdump kernel. A probe failure would then leak
the ida's internal allocations.

Register a devres action right after ida_init(), making devres the single
owner that covers both the unbind and probe failure paths. Also, move the
ida_init() call to the entry of arm_smmu_init_strtab(), as the reservation
will run in the adoption path prior to the regular stream table setup.

Assisted-by: Claude:claude-fable-5
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 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 132bee5fbb1d1..0df6c17a53173 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4494,20 +4494,27 @@ static int arm_smmu_init_strtab_linear(struct arm_smmu_device *smmu)
 	return 0;
 }
 
+static void arm_smmu_deinit_strtab(void *data)
+{
+	struct arm_smmu_device *smmu = data;
+
+	ida_destroy(&smmu->vmid_map);
+}
+
 static int arm_smmu_init_strtab(struct arm_smmu_device *smmu)
 {
 	int ret;
 
+	ida_init(&smmu->vmid_map);
+	ret = devm_add_action_or_reset(smmu->dev, arm_smmu_deinit_strtab, smmu);
+	if (ret)
+		return ret;
+
 	if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB)
 		ret = arm_smmu_init_strtab_2lvl(smmu);
 	else
 		ret = arm_smmu_init_strtab_linear(smmu);
-	if (ret)
-		return ret;
-
-	ida_init(&smmu->vmid_map);
-
-	return 0;
+	return ret;
 }
 
 static int arm_smmu_init_structures(struct arm_smmu_device *smmu)
@@ -5548,7 +5555,6 @@ static void arm_smmu_device_remove(struct platform_device *pdev)
 	iommu_device_sysfs_remove(&smmu->iommu);
 	arm_smmu_device_disable(smmu);
 	iopf_queue_free(smmu->evtq.iopf);
-	ida_destroy(&smmu->vmid_map);
 }
 
 static void arm_smmu_device_shutdown(struct platform_device *pdev)
-- 
2.43.0