> This is subjective, but how about
>
> static bool xxx(void)
> {
> mutex_lock(&cpu_hotplug.lock);
> if (atomic_read(&cpu_hotplug.refcount) == 0)
> return true;
> mutex_unlock(&cpu_hotplug.lock);
> return false;
> }
>
> void cpu_hotplug_begin(void)
> {
> cpu_hotplug.active_writer = current;
>
> cpuhp_lock_acquire();
> wait_event(&cpu_hotplug.wq, xxx());
> }
>
> instead?
>
> Oleg.
>
[ 50.662459] do not call blocking ops when !TASK_RUNNING; state=2 set at
[<000000000017340e>] prepare_to_wait_event+0x7a/0x124
[ 50.662472] ------------[ cut here ]------------
[ 50.662475] WARNING: at kernel/sched/core.c:7301
[ 50.662477] Modules linked in:
[ 50.662482] CPU: 5 PID: 225 Comm: cpu_start_stop. Not tainted 3.18.0+ #59
[ 50.662485] task: 0000000001f94b20 ti: 0000000001ffc000 task.ti:
0000000001ffc000
...
Looks like your suggestion won't work. We can only set the task to
TASK_UNINTERRUPTIBLE after taking the lock.
David
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