lib/interval_tree: fast overlap detection

Allow interval trees to quickly check for overlaps to avoid unnecesary
tree lookups in interval_tree_iter_first().

As of this patch, all interval tree flavors will require using a
'rb_root_cached' such that we can have the leftmost node easily
available.  While most users will make use of this feature, those with
special functions (in addition to the generic insert, delete, search
calls) will avoid using the cached option as they can do funky things
with insertions -- for example, vma_interval_tree_insert_after().

[jglisse@redhat.com: fix deadlock from typo vm_lock_anon_vma()]
  Link: http://lkml.kernel.org/r/20170808225719.20723-1-jglisse@redhat.com
Link: http://lkml.kernel.org/r/20170719014603.19029-12-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Doug Ledford <dledford@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Christian Benvenuti <benve@cisco.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

7 files changed, 26 insertions, 25 deletions

diff --git a/drivers/infiniband/core/umem_rbtree.c b/drivers/infiniband/core/umem_rbtree.c
index d176597b4d78..fc801920e341 100644
--- a/drivers/infiniband/core/umem_rbtree.c
+++ b/drivers/infiniband/core/umem_rbtree.c
@@ -72,7 +72,7 @@ INTERVAL_TREE_DEFINE(struct umem_odp_node, rb, u64, __subtree_last,
 /* @last is not a part of the interval. See comment for function
  * node_last.
  */
-int rbt_ib_umem_for_each_in_range(struct rb_root *root,
+int rbt_ib_umem_for_each_in_range(struct rb_root_cached *root,
 				  u64 start, u64 last,
 				  umem_call_back cb,
 				  void *cookie)
@@ -95,7 +95,7 @@ int rbt_ib_umem_for_each_in_range(struct rb_root *root,
 }
 EXPORT_SYMBOL(rbt_ib_umem_for_each_in_range);
 
-struct ib_umem_odp *rbt_ib_umem_lookup(struct rb_root *root,
+struct ib_umem_odp *rbt_ib_umem_lookup(struct rb_root_cached *root,
 				       u64 addr, u64 length)
 {
 	struct umem_odp_node *node;
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index e0cb99860934..4ab30d832ac5 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -118,7 +118,7 @@ ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
 	ucontext->closing = 0;
 
 #ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
-	ucontext->umem_tree = RB_ROOT;
+	ucontext->umem_tree = RB_ROOT_CACHED;
 	init_rwsem(&ucontext->umem_rwsem);
 	ucontext->odp_mrs_count = 0;
 	INIT_LIST_HEAD(&ucontext->no_private_counters);
diff --git a/drivers/infiniband/hw/hfi1/mmu_rb.c b/drivers/infiniband/hw/hfi1/mmu_rb.c
index 2f0d285dc278..175002c046ed 100644
--- a/drivers/infiniband/hw/hfi1/mmu_rb.c
+++ b/drivers/infiniband/hw/hfi1/mmu_rb.c
@@ -54,7 +54,7 @@
 
 struct mmu_rb_handler {
 	struct mmu_notifier mn;
-	struct rb_root root;
+	struct rb_root_cached root;
 	void *ops_arg;
 	spinlock_t lock;        /* protect the RB tree */
 	struct mmu_rb_ops *ops;
@@ -108,7 +108,7 @@ int hfi1_mmu_rb_register(void *ops_arg, struct mm_struct *mm,
 	if (!handlr)
 		return -ENOMEM;
 
-	handlr->root = RB_ROOT;
+	handlr->root = RB_ROOT_CACHED;
 	handlr->ops = ops;
 	handlr->ops_arg = ops_arg;
 	INIT_HLIST_NODE(&handlr->mn.hlist);
@@ -149,9 +149,9 @@ void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler)
 	INIT_LIST_HEAD(&del_list);
 
 	spin_lock_irqsave(&handler->lock, flags);
-	while ((node = rb_first(&handler->root))) {
+	while ((node = rb_first_cached(&handler->root))) {
 		rbnode = rb_entry(node, struct mmu_rb_node, node);
-		rb_erase(node, &handler->root);
+		rb_erase_cached(node, &handler->root);
 		/* move from LRU list to delete list */
 		list_move(&rbnode->list, &del_list);
 	}
@@ -300,7 +300,7 @@ static void mmu_notifier_mem_invalidate(struct mmu_notifier *mn,
 {
 	struct mmu_rb_handler *handler =
 		container_of(mn, struct mmu_rb_handler, mn);
-	struct rb_root *root = &handler->root;
+	struct rb_root_cached *root = &handler->root;
 	struct mmu_rb_node *node, *ptr = NULL;
 	unsigned long flags;
 	bool added = false;
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c
index c49db7c33979..4381c0a9a873 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.c
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
@@ -227,7 +227,7 @@ static void __usnic_uiom_reg_release(struct usnic_uiom_pd *pd,
 	vpn_last = vpn_start + npages - 1;
 
 	spin_lock(&pd->lock);
-	usnic_uiom_remove_interval(&pd->rb_root, vpn_start,
+	usnic_uiom_remove_interval(&pd->root, vpn_start,
 					vpn_last, &rm_intervals);
 	usnic_uiom_unmap_sorted_intervals(&rm_intervals, pd);
 
@@ -379,7 +379,7 @@ struct usnic_uiom_reg *usnic_uiom_reg_get(struct usnic_uiom_pd *pd,
 	err = usnic_uiom_get_intervals_diff(vpn_start, vpn_last,
 						(writable) ? IOMMU_WRITE : 0,
 						IOMMU_WRITE,
-						&pd->rb_root,
+						&pd->root,
 						&sorted_diff_intervals);
 	if (err) {
 		usnic_err("Failed disjoint interval vpn [0x%lx,0x%lx] err %d\n",
@@ -395,7 +395,7 @@ struct usnic_uiom_reg *usnic_uiom_reg_get(struct usnic_uiom_pd *pd,
 
 	}
 
-	err = usnic_uiom_insert_interval(&pd->rb_root, vpn_start, vpn_last,
+	err = usnic_uiom_insert_interval(&pd->root, vpn_start, vpn_last,
 					(writable) ? IOMMU_WRITE : 0);
 	if (err) {
 		usnic_err("Failed insert interval vpn [0x%lx,0x%lx] err %d\n",
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.h b/drivers/infiniband/hw/usnic/usnic_uiom.h
index 45ca7c1613a7..431efe4143f4 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.h
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.h
@@ -55,7 +55,7 @@ struct usnic_uiom_dev {
 struct usnic_uiom_pd {
 	struct iommu_domain		*domain;
 	spinlock_t			lock;
-	struct rb_root			rb_root;
+	struct rb_root_cached		root;
 	struct list_head		devs;
 	int				dev_cnt;
 };
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.c b/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.c
index 42b4b4c4e452..d399523206c7 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.c
+++ b/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.c
@@ -100,9 +100,9 @@ static int interval_cmp(void *priv, struct list_head *a, struct list_head *b)
 }
 
 static void
-find_intervals_intersection_sorted(struct rb_root *root, unsigned long start,
-					unsigned long last,
-					struct list_head *list)
+find_intervals_intersection_sorted(struct rb_root_cached *root,
+				   unsigned long start, unsigned long last,
+				   struct list_head *list)
 {
 	struct usnic_uiom_interval_node *node;
 
@@ -118,7 +118,7 @@ find_intervals_intersection_sorted(struct rb_root *root, unsigned long start,
 
 int usnic_uiom_get_intervals_diff(unsigned long start, unsigned long last,
 					int flags, int flag_mask,
-					struct rb_root *root,
+					struct rb_root_cached *root,
 					struct list_head *diff_set)
 {
 	struct usnic_uiom_interval_node *interval, *tmp;
@@ -175,7 +175,7 @@ void usnic_uiom_put_interval_set(struct list_head *intervals)
 		kfree(interval);
 }
 
-int usnic_uiom_insert_interval(struct rb_root *root, unsigned long start,
+int usnic_uiom_insert_interval(struct rb_root_cached *root, unsigned long start,
 				unsigned long last, int flags)
 {
 	struct usnic_uiom_interval_node *interval, *tmp;
@@ -246,8 +246,9 @@ err_out:
 	return err;
 }
 
-void usnic_uiom_remove_interval(struct rb_root *root, unsigned long start,
-				unsigned long last, struct list_head *removed)
+void usnic_uiom_remove_interval(struct rb_root_cached *root,
+				unsigned long start, unsigned long last,
+				struct list_head *removed)
 {
 	struct usnic_uiom_interval_node *interval;
 
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.h b/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.h
index c0b0b876ab90..1d7fc3226bca 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.h
+++ b/drivers/infiniband/hw/usnic/usnic_uiom_interval_tree.h
@@ -48,12 +48,12 @@ struct usnic_uiom_interval_node {
 
 extern void
 usnic_uiom_interval_tree_insert(struct usnic_uiom_interval_node *node,
-					struct rb_root *root);
+					struct rb_root_cached *root);
 extern void
 usnic_uiom_interval_tree_remove(struct usnic_uiom_interval_node *node,
-					struct rb_root *root);
+					struct rb_root_cached *root);
 extern struct usnic_uiom_interval_node *
-usnic_uiom_interval_tree_iter_first(struct rb_root *root,
+usnic_uiom_interval_tree_iter_first(struct rb_root_cached *root,
 					unsigned long start,
 					unsigned long last);
 extern struct usnic_uiom_interval_node *
@@ -63,7 +63,7 @@ usnic_uiom_interval_tree_iter_next(struct usnic_uiom_interval_node *node,
  * Inserts {start...last} into {root}.  If there are overlaps,
  * nodes will be broken up and merged
  */
-int usnic_uiom_insert_interval(struct rb_root *root,
+int usnic_uiom_insert_interval(struct rb_root_cached *root,
 				unsigned long start, unsigned long last,
 				int flags);
 /*
@@ -71,7 +71,7 @@ int usnic_uiom_insert_interval(struct rb_root *root,
  * 'removed.' The caller is responsibile for freeing memory of nodes in
  * 'removed.'
  */
-void usnic_uiom_remove_interval(struct rb_root *root,
+void usnic_uiom_remove_interval(struct rb_root_cached *root,
 				unsigned long start, unsigned long last,
 				struct list_head *removed);
 /*
@@ -81,7 +81,7 @@ void usnic_uiom_remove_interval(struct rb_root *root,
 int usnic_uiom_get_intervals_diff(unsigned long start,
 					unsigned long last, int flags,
 					int flag_mask,
-					struct rb_root *root,
+					struct rb_root_cached *root,
 					struct list_head *diff_set);
 /* Call this to free diff_set returned by usnic_uiom_get_intervals_diff */
 void usnic_uiom_put_interval_set(struct list_head *intervals);