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SUNRPC: Prevent looping due to rpc_signal_task() races

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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@huawei.com>
Fixes: 39494194f9 ("SUNRPC: Fix races with rpc_killall_tasks()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
This commit is contained in:
Trond Myklebust 2025-02-01 15:00:02 -05:00 • committed by Anna Schumaker
parent 88025c67fe
commit 5bbd6e863b
3 changed files with 2 additions and 6 deletions
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3
include/linux/sunrpc/sched.h
View file

@ -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.

3
include/trace/events/sunrpc.h
View file

@ -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,

2
net/sunrpc/sched.c
View file

@ -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);