From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
If rpc_signal_task() is called while a task is in an rpc_call_done()
callback function, and the latter calls rpc_restart_call(), the task can
end up looping due to the RPC_TASK_SIGNALLED flag being set without the
tk_rpc_status being set.
Removing the redundant mechanism for signalling the task fixes the
looping behaviour.
Reported-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
Fixes: 39494194f93b ("SUNRPC: Fix races with rpc_killall_tasks()")
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
include/linux/sunrpc/sched.h | 3 +--
include/trace/events/sunrpc.h | 3 +--
net/sunrpc/sched.c | 2 --
3 files changed, 2 insertions(+), 6 deletions(-)
diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index fec1e8a1570c..eac57914dcf3 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -158,7 +158,6 @@ enum {
RPC_TASK_NEED_XMIT,
RPC_TASK_NEED_RECV,
RPC_TASK_MSG_PIN_WAIT,
- RPC_TASK_SIGNALLED,
};
#define rpc_test_and_set_running(t) \
@@ -171,7 +170,7 @@ enum {
#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) (READ_ONCE(task->tk_rpc_status) == -ERESTARTSYS)
/*
* Task priorities.
diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index b13dc275ef4a..851841336ee6 100644
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -360,8 +360,7 @@ TRACE_EVENT(rpc_request,
{ (1UL << RPC_TASK_ACTIVE), "ACTIVE" }, \
{ (1UL << RPC_TASK_NEED_XMIT), "NEED_XMIT" }, \
{ (1UL << RPC_TASK_NEED_RECV), "NEED_RECV" }, \
- { (1UL << RPC_TASK_MSG_PIN_WAIT), "MSG_PIN_WAIT" }, \
- { (1UL << RPC_TASK_SIGNALLED), "SIGNALLED" })
+ { (1UL << RPC_TASK_MSG_PIN_WAIT), "MSG_PIN_WAIT" })
DECLARE_EVENT_CLASS(rpc_task_running,
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index cef623ea1506..9b45fbdc90ca 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -864,8 +864,6 @@ void rpc_signal_task(struct rpc_task *task)
if (!rpc_task_set_rpc_status(task, -ERESTARTSYS))
return;
trace_rpc_task_signalled(task, task->tk_action);
- set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
- smp_mb__after_atomic();
queue = READ_ONCE(task->tk_waitqueue);
if (queue)
rpc_wake_up_queued_task(queue, task);
--
2.48.1
