From d1296acac0c1925be1f16f81d6deffb899467ef7 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Thu, 22 Oct 2020 17:40:33 -0400
Subject: [PATCH] SUNRPC: rpc_wake_up() should wake up tasks in the correct
 order

[ Upstream commit e4c72201b6ec3173dfe13fa2e2335a3ad78d4921 ]

Currently, we wake up the tasks by priority queue ordering, which means
that we ignore the batching that is supposed to help with QoS issues.

Fixes: c049f8ea9a0d ("SUNRPC: Remove the bh-safe lock requirement on the rpc_wait_queue->lock")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/sunrpc/sched.c | 67 +++++++++++++++++++++++++---------------------
 1 file changed, 36 insertions(+), 31 deletions(-)

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index f06d7c315017..cf702a5f7fe5 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -675,6 +675,23 @@ struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
 }
 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 
+/**
+ * rpc_wake_up_locked - wake up all rpc_tasks
+ * @queue: rpc_wait_queue on which the tasks are sleeping
+ *
+ */
+static void rpc_wake_up_locked(struct rpc_wait_queue *queue)
+{
+	struct rpc_task *task;
+
+	for (;;) {
+		task = __rpc_find_next_queued(queue);
+		if (task == NULL)
+			break;
+		rpc_wake_up_task_queue_locked(queue, task);
+	}
+}
+
 /**
  * rpc_wake_up - wake up all rpc_tasks
  * @queue: rpc_wait_queue on which the tasks are sleeping
@@ -683,26 +700,29 @@ EXPORT_SYMBOL_GPL(rpc_wake_up_next);
  */
 void rpc_wake_up(struct rpc_wait_queue *queue)
 {
-	struct list_head *head;
-
 	spin_lock(&queue->lock);
-	head = &queue->tasks[queue->maxpriority];
-	for (;;) {
-		while (!list_empty(head)) {
-			struct rpc_task *task;
-			task = list_first_entry(head,
-					struct rpc_task,
-					u.tk_wait.list);
-			rpc_wake_up_task_queue_locked(queue, task);
-		}
-		if (head == &queue->tasks[0])
-			break;
-		head--;
-	}
+	rpc_wake_up_locked(queue);
 	spin_unlock(&queue->lock);
 }
 EXPORT_SYMBOL_GPL(rpc_wake_up);
 
+/**
+ * rpc_wake_up_status_locked - wake up all rpc_tasks and set their status value.
+ * @queue: rpc_wait_queue on which the tasks are sleeping
+ * @status: status value to set
+ */
+static void rpc_wake_up_status_locked(struct rpc_wait_queue *queue, int status)
+{
+	struct rpc_task *task;
+
+	for (;;) {
+		task = __rpc_find_next_queued(queue);
+		if (task == NULL)
+			break;
+		rpc_wake_up_task_queue_set_status_locked(queue, task, status);
+	}
+}
+
 /**
  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
  * @queue: rpc_wait_queue on which the tasks are sleeping
@@ -712,23 +732,8 @@ EXPORT_SYMBOL_GPL(rpc_wake_up);
  */
 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 {
-	struct list_head *head;
-
 	spin_lock(&queue->lock);
-	head = &queue->tasks[queue->maxpriority];
-	for (;;) {
-		while (!list_empty(head)) {
-			struct rpc_task *task;
-			task = list_first_entry(head,
-					struct rpc_task,
-					u.tk_wait.list);
-			task->tk_status = status;
-			rpc_wake_up_task_queue_locked(queue, task);
-		}
-		if (head == &queue->tasks[0])
-			break;
-		head--;
-	}
+	rpc_wake_up_status_locked(queue, status);
 	spin_unlock(&queue->lock);
 }
 EXPORT_SYMBOL_GPL(rpc_wake_up_status);