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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2018-03-22 18:22:34 +0300
committerJoerg Roedel <jroedel@suse.de>2018-03-29 11:38:14 +0300
commit779da73273fc4c4c6f41579a95e4fb7880a1720e (patch)
tree522d6bfd4cf79310c320293ba6b13375515926f4 /drivers/iommu/amd_iommu.c
parent39ffe39545cd5cb5b8cee9f0469165cf24dc62c2 (diff)
downloadlinux-779da73273fc4c4c6f41579a95e4fb7880a1720e.tar.xz
iommu/amd: Turn dev_data_list into a lock less list
alloc_dev_data() adds new items to dev_data_list and search_dev_data() is searching for items in this list. Both protect the access to the list with a spinlock. There is no need to navigate forth and back within the list and there is also no deleting of a specific item. This qualifies the list to become a lock less list and as part of this, the spinlock can be removed. With this change the ordering of those items within the list is changed: before the change new items were added to the end of the list, now they are added to the front. I don't think it matters but wanted to mention it. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu/amd_iommu.c')
-rw-r--r--drivers/iommu/amd_iommu.c28
1 files changed, 10 insertions, 18 deletions
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 121c54f1c768..d4c2b1a11924 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -83,8 +83,7 @@
static DEFINE_RWLOCK(amd_iommu_devtable_lock);
/* List of all available dev_data structures */
-static LIST_HEAD(dev_data_list);
-static DEFINE_SPINLOCK(dev_data_list_lock);
+static LLIST_HEAD(dev_data_list);
LIST_HEAD(ioapic_map);
LIST_HEAD(hpet_map);
@@ -203,40 +202,33 @@ static struct dma_ops_domain* to_dma_ops_domain(struct protection_domain *domain
static struct iommu_dev_data *alloc_dev_data(u16 devid)
{
struct iommu_dev_data *dev_data;
- unsigned long flags;
dev_data = kzalloc(sizeof(*dev_data), GFP_KERNEL);
if (!dev_data)
return NULL;
dev_data->devid = devid;
-
- spin_lock_irqsave(&dev_data_list_lock, flags);
- list_add_tail(&dev_data->dev_data_list, &dev_data_list);
- spin_unlock_irqrestore(&dev_data_list_lock, flags);
-
ratelimit_default_init(&dev_data->rs);
+ llist_add(&dev_data->dev_data_list, &dev_data_list);
return dev_data;
}
static struct iommu_dev_data *search_dev_data(u16 devid)
{
struct iommu_dev_data *dev_data;
- unsigned long flags;
+ struct llist_node *node;
+
+ if (llist_empty(&dev_data_list))
+ return NULL;
- spin_lock_irqsave(&dev_data_list_lock, flags);
- list_for_each_entry(dev_data, &dev_data_list, dev_data_list) {
+ node = dev_data_list.first;
+ llist_for_each_entry(dev_data, node, dev_data_list) {
if (dev_data->devid == devid)
- goto out_unlock;
+ return dev_data;
}
- dev_data = NULL;
-
-out_unlock:
- spin_unlock_irqrestore(&dev_data_list_lock, flags);
-
- return dev_data;
+ return NULL;
}
static int __last_alias(struct pci_dev *pdev, u16 alias, void *data)