iommu/arm-smmu-v3: Return -EBUSY when trying to re-add a device

Although we WARN in arm_smmu_add_device() if the device being added has
been added already without a subsequent call to arm_smmu_remove_device(),
we still continue half-heartedly, initialising the stream-table for any
new StreamIDs that may have magically appeared and re-establishing device
links that should still be there from last time.

Given that calling ->add_device() twice without removing the device in the
meantime is indicative of an error in the caller, just return -EBUSY after
warning.

Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Jean Philippe-Brucker <jean-philippe@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 59dbd63..5e04c1f 100644 (file)
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2794,28 +2794,23 @@ static int arm_smmu_add_device(struct device *dev)
 
        if (!fwspec || fwspec->ops != &arm_smmu_ops)
                return -ENODEV;
-       /*
-        * We _can_ actually withstand dodgy bus code re-calling add_device()
-        * without an intervening remove_device()/of_xlate() sequence, but
-        * we're not going to do so quietly...
-        */
-       if (WARN_ON_ONCE(fwspec->iommu_priv)) {
-               master = fwspec->iommu_priv;
-               smmu = master->smmu;
-       } else {
-               smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode);
-               if (!smmu)
-                       return -ENODEV;
-               master = kzalloc(sizeof(*master), GFP_KERNEL);
-               if (!master)
-                       return -ENOMEM;
 
-               master->dev = dev;
-               master->smmu = smmu;
-               master->sids = fwspec->ids;
-               master->num_sids = fwspec->num_ids;
-               fwspec->iommu_priv = master;
-       }
+       if (WARN_ON_ONCE(fwspec->iommu_priv))
+               return -EBUSY;
+
+       smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode);
+       if (!smmu)
+               return -ENODEV;
+
+       master = kzalloc(sizeof(*master), GFP_KERNEL);
+       if (!master)
+               return -ENOMEM;
+
+       master->dev = dev;
+       master->smmu = smmu;
+       master->sids = fwspec->ids;
+       master->num_sids = fwspec->num_ids;
+       fwspec->iommu_priv = master;
 
        /* Check the SIDs are in range of the SMMU and our stream table */
        for (i = 0; i < master->num_sids; i++) {