1 files changed, 63 insertions, 38 deletions

diff --git a/drivers/infiniband/hw/hfi1/mmu_rb.c b/drivers/infiniband/hw/hfi1/mmu_rb.c
index 1cea8b0c78e0..a864423c256d 100644
--- a/drivers/infiniband/hw/hfi1/mmu_rb.c
+++ b/drivers/infiniband/hw/hfi1/mmu_rb.c
@@ -19,8 +19,7 @@ static int mmu_notifier_range_start(struct mmu_notifier *,
 		const struct mmu_notifier_range *);
 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *,
 					   unsigned long, unsigned long);
-static void do_remove(struct mmu_rb_handler *handler,
-		      struct list_head *del_list);
+static void release_immediate(struct kref *refcount);
 static void handle_remove(struct work_struct *work);
 
 static const struct mmu_notifier_ops mn_opts = {
@@ -106,7 +105,11 @@ void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler)
 	}
 	spin_unlock_irqrestore(&handler->lock, flags);
 
-	do_remove(handler, &del_list);
+	while (!list_empty(&del_list)) {
+		rbnode = list_first_entry(&del_list, struct mmu_rb_node, list);
+		list_del(&rbnode->list);
+		kref_put(&rbnode->refcount, release_immediate);
+	}
 
 	/* Now the mm may be freed. */
 	mmdrop(handler->mn.mm);
@@ -134,12 +137,6 @@ int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
 	}
 	__mmu_int_rb_insert(mnode, &handler->root);
 	list_add_tail(&mnode->list, &handler->lru_list);
-
-	ret = handler->ops->insert(handler->ops_arg, mnode);
-	if (ret) {
-		__mmu_int_rb_remove(mnode, &handler->root);
-		list_del(&mnode->list); /* remove from LRU list */
-	}
 	mnode->handler = handler;
 unlock:
 	spin_unlock_irqrestore(&handler->lock, flags);
@@ -183,6 +180,48 @@ static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *handler,
 	return node;
 }
 
+/*
+ * Must NOT call while holding mnode->handler->lock.
+ * mnode->handler->ops->remove() may sleep and mnode->handler->lock is a
+ * spinlock.
+ */
+static void release_immediate(struct kref *refcount)
+{
+	struct mmu_rb_node *mnode =
+		container_of(refcount, struct mmu_rb_node, refcount);
+	mnode->handler->ops->remove(mnode->handler->ops_arg, mnode);
+}
+
+/* Caller must hold mnode->handler->lock */
+static void release_nolock(struct kref *refcount)
+{
+	struct mmu_rb_node *mnode =
+		container_of(refcount, struct mmu_rb_node, refcount);
+	list_move(&mnode->list, &mnode->handler->del_list);
+	queue_work(mnode->handler->wq, &mnode->handler->del_work);
+}
+
+/*
+ * struct mmu_rb_node->refcount kref_put() callback.
+ * Adds mmu_rb_node to mmu_rb_node->handler->del_list and queues
+ * handler->del_work on handler->wq.
+ * Does not remove mmu_rb_node from handler->lru_list or handler->rb_root.
+ * Acquires mmu_rb_node->handler->lock; do not call while already holding
+ * handler->lock.
+ */
+void hfi1_mmu_rb_release(struct kref *refcount)
+{
+	struct mmu_rb_node *mnode =
+		container_of(refcount, struct mmu_rb_node, refcount);
+	struct mmu_rb_handler *handler = mnode->handler;
+	unsigned long flags;
+
+	spin_lock_irqsave(&handler->lock, flags);
+	list_move(&mnode->list, &mnode->handler->del_list);
+	spin_unlock_irqrestore(&handler->lock, flags);
+	queue_work(handler->wq, &handler->del_work);
+}
+
 void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
 {
 	struct mmu_rb_node *rbnode, *ptr;
@@ -197,6 +236,10 @@ void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
 
 	spin_lock_irqsave(&handler->lock, flags);
 	list_for_each_entry_safe(rbnode, ptr, &handler->lru_list, list) {
+		/* refcount == 1 implies mmu_rb_handler has only rbnode ref */
+		if (kref_read(&rbnode->refcount) > 1)
+			continue;
+
 		if (handler->ops->evict(handler->ops_arg, rbnode, evict_arg,
 					&stop)) {
 			__mmu_int_rb_remove(rbnode, &handler->root);
@@ -209,7 +252,7 @@ void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
 	spin_unlock_irqrestore(&handler->lock, flags);
 
 	list_for_each_entry_safe(rbnode, ptr, &del_list, list) {
-		handler->ops->remove(handler->ops_arg, rbnode);
+		kref_put(&rbnode->refcount, release_immediate);
 	}
 }
 
@@ -221,7 +264,6 @@ static int mmu_notifier_range_start(struct mmu_notifier *mn,
 	struct rb_root_cached *root = &handler->root;
 	struct mmu_rb_node *node, *ptr = NULL;
 	unsigned long flags;
-	bool added = false;
 
 	spin_lock_irqsave(&handler->lock, flags);
 	for (node = __mmu_int_rb_iter_first(root, range->start, range->end-1);
@@ -230,39 +272,17 @@ static int mmu_notifier_range_start(struct mmu_notifier *mn,
 		ptr = __mmu_int_rb_iter_next(node, range->start,
 					     range->end - 1);
 		trace_hfi1_mmu_mem_invalidate(node->addr, node->len);
-		if (handler->ops->invalidate(handler->ops_arg, node)) {
-			__mmu_int_rb_remove(node, root);
-			/* move from LRU list to delete list */
-			list_move(&node->list, &handler->del_list);
-			added = true;
-		}
+		/* Remove from rb tree and lru_list. */
+		__mmu_int_rb_remove(node, root);
+		list_del_init(&node->list);
+		kref_put(&node->refcount, release_nolock);
 	}
 	spin_unlock_irqrestore(&handler->lock, flags);
 
-	if (added)
-		queue_work(handler->wq, &handler->del_work);
-
 	return 0;
 }
 
 /*
- * Call the remove function for the given handler and the list.  This
- * is expected to be called with a delete list extracted from handler.
- * The caller should not be holding the handler lock.
- */
-static void do_remove(struct mmu_rb_handler *handler,
-		      struct list_head *del_list)
-{
-	struct mmu_rb_node *node;
-
-	while (!list_empty(del_list)) {
-		node = list_first_entry(del_list, struct mmu_rb_node, list);
-		list_del(&node->list);
-		handler->ops->remove(handler->ops_arg, node);
-	}
-}
-
-/*
  * Work queue function to remove all nodes that have been queued up to
  * be removed.  The key feature is that mm->mmap_lock is not being held
  * and the remove callback can sleep while taking it, if needed.
@@ -274,11 +294,16 @@ static void handle_remove(struct work_struct *work)
 						del_work);
 	struct list_head del_list;
 	unsigned long flags;
+	struct mmu_rb_node *node;
 
 	/* remove anything that is queued to get removed */
 	spin_lock_irqsave(&handler->lock, flags);
 	list_replace_init(&handler->del_list, &del_list);
 	spin_unlock_irqrestore(&handler->lock, flags);
 
-	do_remove(handler, &del_list);
+	while (!list_empty(&del_list)) {
+		node = list_first_entry(&del_list, struct mmu_rb_node, list);
+		list_del(&node->list);
+		handler->ops->remove(handler->ops_arg, node);
+	}
 }