waterDataFluctuationCorrelation connectionSignalSlot.c 韩正义 commit at 2020-09-18

waterDataFluctuationCorrelation/monitoringDataProcessing/connectionSignalSlot.c

@@ -127,3 +127,187 @@ err_free:
 
 static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
 				      struct request_queue *q)
+{
+	struct blkcg_gq *blkg;
+
+	blkg = rcu_dereference(blkcg->blkg_hint);
+	if (blkg && blkg->q == q)
+		return blkg;
+
+	/*
+	 * Hint didn't match.  Look up from the radix tree.  Note that we
+	 * may not be holding queue_lock and thus are not sure whether
+	 * @blkg from blkg_tree has already been removed or not, so we
+	 * can't update hint to the lookup result.  Leave it to the caller.
+	 */
+	blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
+	if (blkg && blkg->q == q)
+		return blkg;
+
+	return NULL;
+}
+
+/**
+ * blkg_lookup - lookup blkg for the specified blkcg - q pair
+ * @blkcg: blkcg of interest
+ * @q: request_queue of interest
+ *
+ * Lookup blkg for the @blkcg - @q pair.  This function should be called
+ * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
+ * - see blk_queue_bypass_start() for details.
+ */
+struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	if (unlikely(blk_queue_bypass(q)))
+		return NULL;
+	return __blkg_lookup(blkcg, q);
+}
+EXPORT_SYMBOL_GPL(blkg_lookup);
+
+/*
+ * If @new_blkg is %NULL, this function tries to allocate a new one as
+ * necessary using %GFP_ATOMIC.  @new_blkg is always consumed on return.
+ */
+static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
+					     struct request_queue *q,
+					     struct blkcg_gq *new_blkg)
+{
+	struct blkcg_gq *blkg;
+	int ret;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+	lockdep_assert_held(q->queue_lock);
+
+	/* lookup and update hint on success, see __blkg_lookup() for details */
+	blkg = __blkg_lookup(blkcg, q);
+	if (blkg) {
+		rcu_assign_pointer(blkcg->blkg_hint, blkg);
+		goto out_free;
+	}
+
+	/* blkg holds a reference to blkcg */
+	if (!css_tryget(&blkcg->css)) {
+		blkg = ERR_PTR(-EINVAL);
+		goto out_free;
+	}
+
+	/* allocate */
+	if (!new_blkg) {
+		new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);
+		if (unlikely(!new_blkg)) {
+			blkg = ERR_PTR(-ENOMEM);
+			goto out_put;
+		}
+	}
+	blkg = new_blkg;
+
+	/* insert */
+	spin_lock(&blkcg->lock);
+	ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
+	if (likely(!ret)) {
+		hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
+		list_add(&blkg->q_node, &q->blkg_list);
+	}
+	spin_unlock(&blkcg->lock);
+
+	if (!ret)
+		return blkg;
+
+	blkg = ERR_PTR(ret);
+out_put:
+	css_put(&blkcg->css);
+out_free:
+	blkg_free(new_blkg);
+	return blkg;
+}
+
+struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
+				    struct request_queue *q)
+{
+	/*
+	 * This could be the first entry point of blkcg implementation and
+	 * we shouldn't allow anything to go through for a bypassing queue.
+	 */
+	if (unlikely(blk_queue_bypass(q)))
+		return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY);
+	return __blkg_lookup_create(blkcg, q, NULL);
+}
+EXPORT_SYMBOL_GPL(blkg_lookup_create);
+
+static void blkg_destroy(struct blkcg_gq *blkg)
+{
+	struct blkcg *blkcg = blkg->blkcg;
+
+	lockdep_assert_held(blkg->q->queue_lock);
+	lockdep_assert_held(&blkcg->lock);
+
+	/* Something wrong if we are trying to remove same group twice */
+	WARN_ON_ONCE(list_empty(&blkg->q_node));
+	WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
+
+	radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
+	list_del_init(&blkg->q_node);
+	hlist_del_init_rcu(&blkg->blkcg_node);
+
+	/*
+	 * Both setting lookup hint to and clearing it from @blkg are done
+	 * under queue_lock.  If it's not pointing to @blkg now, it never
+	 * will.  Hint assignment itself can race safely.
+	 */
+	if (rcu_dereference_raw(blkcg->blkg_hint) == blkg)
+		rcu_assign_pointer(blkcg->blkg_hint, NULL);
+
+	/*
+	 * Put the reference taken at the time of creation so that when all
+	 * queues are gone, group can be destroyed.
+	 */
+	blkg_put(blkg);
+}
+
+/**
+ * blkg_destroy_all - destroy all blkgs associated with a request_queue
+ * @q: request_queue of interest
+ *
+ * Destroy all blkgs associated with @q.
+ */
+static void blkg_destroy_all(struct request_queue *q)
+{
+	struct blkcg_gq *blkg, *n;
+
+	lockdep_assert_held(q->queue_lock);
+
+	list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
+		struct blkcg *blkcg = blkg->blkcg;
+
+		spin_lock(&blkcg->lock);
+		blkg_destroy(blkg);
+		spin_unlock(&blkcg->lock);
+	}
+
+	/*
+	 * root blkg is destroyed.  Just clear the pointer since
+	 * root_rl does not take reference on root blkg.
+	 */
+	q->root_blkg = NULL;
+	q->root_rl.blkg = NULL;
+}
+
+static void blkg_rcu_free(struct rcu_head *rcu_head)
+{
+	blkg_free(container_of(rcu_head, struct blkcg_gq, rcu_head));
+}
+
+void __blkg_release(struct blkcg_gq *blkg)
+{
+	/* release the extra blkcg reference this blkg has been holding */
+	css_put(&blkg->blkcg->css);
+
+	/*
+	 * A group is freed in rcu manner. But having an rcu lock does not
+	 * mean that one can access all the fields of blkg and assume these
+	 * are valid. For example, don't try to follow throtl_data and
+	 * request queue links.
+	 *
+	 * Having a reference to blkg under an rcu allows acess to only