From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Sat, 4 Apr 2020 19:52:21 -0400
Subject: [PATCH] SUNRPC: Don't start a timer on an already queued rpc task
Git-commit: 1fab7dc477241c12f977955aa6baea7938b6f08d
Patch-mainline: v5.7
References: git-fixes

Move the test for whether a task is already queued to prevent
corruption of the timer list in __rpc_sleep_on_priority_timeout().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 net/sunrpc/sched.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -199,10 +199,6 @@ static void __rpc_add_wait_queue(struct
 		struct rpc_task *task,
 		unsigned char queue_priority)
 {
-	WARN_ON_ONCE(RPC_IS_QUEUED(task));
-	if (RPC_IS_QUEUED(task))
-		return;
-
 	INIT_LIST_HEAD(&task->u.tk_wait.timer_list);
 	if (RPC_IS_PRIORITY(queue))
 		__rpc_add_wait_queue_priority(queue, task, queue_priority);
@@ -375,7 +371,7 @@ static void rpc_make_runnable(struct wor
  * NB: An RPC task will only receive interrupt-driven events as long
  * as it's on a wait queue.
  */
-static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
+static void __rpc_do_sleep_on_priority(struct rpc_wait_queue *q,
 		struct rpc_task *task,
 		unsigned char queue_priority)
 {
@@ -388,12 +384,23 @@ static void __rpc_sleep_on_priority(stru
 
 }
 
+static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
+		struct rpc_task *task,
+		unsigned char queue_priority)
+{
+	if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
+		return;
+	__rpc_do_sleep_on_priority(q, task, queue_priority);
+}
+
 static void __rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
 		struct rpc_task *task, unsigned long timeout,
 		unsigned char queue_priority)
 {
+	if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
+		return;
 	if (time_is_after_jiffies(timeout)) {
-		__rpc_sleep_on_priority(q, task, queue_priority);
+		__rpc_do_sleep_on_priority(q, task, queue_priority);
 		__rpc_add_timer(q, task, timeout);
 	} else
 		task->tk_status = -ETIMEDOUT;