stop_machine: remove try_stop_cpus helper

try_stop_cpus is not used after this:

commit c190c3b ("rcu: Switch synchronize_sched_expedited() to
stop_one_cpu()")

So remove it.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191214195107.26480-1-tiny.windzz@gmail.com

include/linux/stop_machine.h

@@ -33,7 +33,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
 bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
 			 struct cpu_stop_work *work_buf);
 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
-int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
 void stop_machine_park(int cpu);
 void stop_machine_unpark(int cpu);
 void stop_machine_yield(const struct cpumask *cpumask);
@@ -90,12 +89,6 @@ static inline int stop_cpus(const struct cpumask *cpumask,
 	return -ENOENT;
 }
 
-static inline int try_stop_cpus(const struct cpumask *cpumask,
-				cpu_stop_fn_t fn, void *arg)
-{
-	return stop_cpus(cpumask, fn, arg);
-}
-
 #endif	/* CONFIG_SMP */
 
 /*

kernel/stop_machine.c

@@ -453,36 +453,6 @@ int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg)
 	return ret;
 }
 
-/**
- * try_stop_cpus - try to stop multiple cpus
- * @cpumask: cpus to stop
- * @fn: function to execute
- * @arg: argument to @fn
- *
- * Identical to stop_cpus() except that it fails with -EAGAIN if
- * someone else is already using the facility.
- *
- * CONTEXT:
- * Might sleep.
- *
- * RETURNS:
- * -EAGAIN if someone else is already stopping cpus, -ENOENT if
- * @fn(@arg) was not executed at all because all cpus in @cpumask were
- * offline; otherwise, 0 if all executions of @fn returned 0, any non
- * zero return value if any returned non zero.
- */
-int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg)
-{
-	int ret;
-
-	/* static works are used, process one request at a time */
-	if (!mutex_trylock(&stop_cpus_mutex))
-		return -EAGAIN;
-	ret = __stop_cpus(cpumask, fn, arg);
-	mutex_unlock(&stop_cpus_mutex);
-	return ret;
-}
-
 static int cpu_stop_should_run(unsigned int cpu)
 {
 	struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);