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Subject: [PATCH RFC2 2/2] sunrpc: Ensure signalled RPC tasks exit
From:   Chuck Lever <chuck.lever@oracle.com>
To:     trondmy@hammerspace.com
Cc:     linux-nfs@vger.kernel.org
Date:   Thu, 23 Apr 2020 15:43:17 -0400
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If an RPC task is signaled while it is running and the transport is
not connected, it will never sleep and never be terminated. This can
happen when a RPC transport is shut down: the remaining tasks are
signalled, but the transport is disconnected.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/linux/sunrpc/sched.h |    3 ++-
 net/sunrpc/sched.c           |   14 ++++++--------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index df696efdd675..9f5e48f154c5 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -170,7 +170,8 @@ struct rpc_task_setup {
 
 #define RPC_IS_ACTIVATED(t)	test_bit(RPC_TASK_ACTIVE, &(t)->tk_runstate)
 
-#define RPC_SIGNALLED(t)	test_bit(RPC_TASK_SIGNALLED, &(t)->tk_runstate)
+#define RPC_SIGNALLED(t)	\
+	unlikely(test_bit(RPC_TASK_SIGNALLED, &(t)->tk_runstate) != 0)
 
 /*
  * Task priorities.
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 7eba20a88438..99b7b834a110 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -912,6 +912,12 @@ static void __rpc_execute(struct rpc_task *task)
 		trace_rpc_task_run_action(task, do_action);
 		do_action(task);
 
+		if (RPC_SIGNALLED(task)) {
+			task->tk_rpc_status = -ERESTARTSYS;
+			rpc_exit(task, -ERESTARTSYS);
+			break;
+		}
+
 		/*
 		 * Lockless check for whether task is sleeping or not.
 		 */
@@ -919,14 +925,6 @@ static void __rpc_execute(struct rpc_task *task)
 			continue;
 
 		/*
-		 * Signalled tasks should exit rather than sleep.
-		 */
-		if (RPC_SIGNALLED(task)) {
-			task->tk_rpc_status = -ERESTARTSYS;
-			rpc_exit(task, -ERESTARTSYS);
-		}
-
-		/*
 		 * The queue->lock protects against races with
 		 * rpc_make_runnable().
 		 *