iommu/amd: Fix cleanup_domain for mass device removal

When multiple devices are detached in __detach_device, they
are also removed from the domains dev_list. This makes it
unsafe to use list_for_each_entry_safe, as the next pointer
might also not be in the list anymore after __detach_device
returns. So just repeatedly remove the first element of the
list until it is empty.

Cc: stable@vger.kernel.org
Tested-by: Marti Raudsepp <marti@juffo.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -3149,14 +3149,16 @@ free_domains:
 
 static void cleanup_domain(struct protection_domain *domain)
 {
-	struct iommu_dev_data *dev_data, *next;
+	struct iommu_dev_data *entry;
 	unsigned long flags;
 
 	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
 
-	list_for_each_entry_safe(dev_data, next, &domain->dev_list, list) {
+	while (!list_empty(&domain->dev_list)) {
-		__detach_device(dev_data);
+		entry = list_first_entry(&domain->dev_list,
-		atomic_set(&dev_data->bind, 0);
+					 struct iommu_dev_data, list);
+		__detach_device(entry);
+		atomic_set(&entry->bind, 0);
 	}
 
 	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);