Currently, the sync_sched_exp_online_cleanup() is invoked in cpuhp per-cpu kthreads when CPU is going online, so the CPU id obtained by get_cpu() should always be equal to the CPU id of the passed parameter, that is to say, the smp_call_function_single() never be invoked, if be invoked, there may be problem with cpu-hotplug, this commit add WARN_ON_ONCE() to remind everyone. Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx> --- kernel/rcu/tree_exp.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index be667583a554..ae8dcfd4486c 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -865,6 +865,8 @@ static void sync_sched_exp_online_cleanup(int cpu) put_cpu(); return; } + + WARN_ON_ONCE(my_cpu != cpu); /* Quiescent state needed on some other CPU, send IPI. */ ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0); put_cpu(); -- 2.25.1
