98 lines
3.1 KiB
Diff
98 lines
3.1 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Thu, 22 Mar 2018 16:22:34 +0100
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Subject: [PATCH 02/10] iommu/amd: Turn dev_data_list into a lock less list
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Upstream commit 779da73273fc4c4c6f41579a95e4fb7880a1720e
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alloc_dev_data() adds new items to dev_data_list and search_dev_data()
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is searching for items in this list. Both protect the access to the list
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with a spinlock.
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There is no need to navigate forth and back within the list and there is
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also no deleting of a specific item. This qualifies the list to become a
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lock less list and as part of this, the spinlock can be removed.
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With this change the ordering of those items within the list is changed:
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before the change new items were added to the end of the list, now they
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are added to the front. I don't think it matters but wanted to mention
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it.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Joerg Roedel <jroedel@suse.de>
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---
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drivers/iommu/amd_iommu.c | 28 ++++++++++------------------
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drivers/iommu/amd_iommu_types.h | 2 +-
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2 files changed, 11 insertions(+), 19 deletions(-)
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--- a/drivers/iommu/amd_iommu.c
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+++ b/drivers/iommu/amd_iommu.c
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@@ -83,8 +83,7 @@
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static DEFINE_RWLOCK(amd_iommu_devtable_lock);
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/* List of all available dev_data structures */
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-static LIST_HEAD(dev_data_list);
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-static DEFINE_SPINLOCK(dev_data_list_lock);
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+static LLIST_HEAD(dev_data_list);
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LIST_HEAD(ioapic_map);
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LIST_HEAD(hpet_map);
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@@ -203,40 +202,33 @@ static struct dma_ops_domain* to_dma_ops
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static struct iommu_dev_data *alloc_dev_data(u16 devid)
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{
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struct iommu_dev_data *dev_data;
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- unsigned long flags;
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dev_data = kzalloc(sizeof(*dev_data), GFP_KERNEL);
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if (!dev_data)
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return NULL;
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dev_data->devid = devid;
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-
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- spin_lock_irqsave(&dev_data_list_lock, flags);
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- list_add_tail(&dev_data->dev_data_list, &dev_data_list);
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- spin_unlock_irqrestore(&dev_data_list_lock, flags);
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-
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ratelimit_default_init(&dev_data->rs);
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+ llist_add(&dev_data->dev_data_list, &dev_data_list);
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return dev_data;
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}
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static struct iommu_dev_data *search_dev_data(u16 devid)
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{
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struct iommu_dev_data *dev_data;
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- unsigned long flags;
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+ struct llist_node *node;
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+
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+ if (llist_empty(&dev_data_list))
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+ return NULL;
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- spin_lock_irqsave(&dev_data_list_lock, flags);
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- list_for_each_entry(dev_data, &dev_data_list, dev_data_list) {
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+ node = dev_data_list.first;
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+ llist_for_each_entry(dev_data, node, dev_data_list) {
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if (dev_data->devid == devid)
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- goto out_unlock;
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+ return dev_data;
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}
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- dev_data = NULL;
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-
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-out_unlock:
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- spin_unlock_irqrestore(&dev_data_list_lock, flags);
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-
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- return dev_data;
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+ return NULL;
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}
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static int __last_alias(struct pci_dev *pdev, u16 alias, void *data)
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--- a/drivers/iommu/amd_iommu_types.h
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+++ b/drivers/iommu/amd_iommu_types.h
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@@ -627,7 +627,7 @@ struct devid_map {
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*/
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struct iommu_dev_data {
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struct list_head list; /* For domain->dev_list */
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- struct list_head dev_data_list; /* For global dev_data_list */
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+ struct llist_node dev_data_list; /* For global dev_data_list */
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struct protection_domain *domain; /* Domain the device is bound to */
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u16 devid; /* PCI Device ID */
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u16 alias; /* Alias Device ID */
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