Correct wakeup() dance in sensor_task_work()

Problem noticed by krw

diff --git a/sys/kern/kern_sensors.c b/sys/kern/kern_sensors.c
index 7cbe401..48c0fb0 100644 (file)
--- a/sys/kern/kern_sensors.c
+++ b/sys/kern/kern_sensors.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_sensors.c,v 1.37 2017/04/08 04:06:01 deraadt Exp $       */
+/*     $OpenBSD: kern_sensors.c,v 1.38 2017/04/09 15:47:18 deraadt Exp $       */
 
 /*
  * Copyright (c) 2005 David Gwynne <dlg@openbsd.org>
@@ -263,8 +263,10 @@ sensor_task_work(void *xst)
        if (period > 0 && !sensors_quiesced)
                st->func(st->arg);
        rw_exit_write(&st->lock);
-       if (sensors_quiesced && atomic_dec_int_nv(&sensors_running) == 0)
-               wakeup(&sensors_running);
+       if (atomic_dec_int_nv(&sensors_running) == 0) {
+               if (sensors_quiesced)
+                       wakeup(&sensors_running);
+       }
 
        if (period == 0)
                free(st, M_DEVBUF, sizeof(*st));