driver core: Read atomic counter once in driver_probe_done()

Between printing the debug message and actual check atomic counter can be
altered. For better debugging experience read atomic counter value only once.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Ferry Toth <fntoth@gmail.com>
Link: https://lore.kernel.org/r/20200324122023.9649-2-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/dd.c

@@ -644,9 +644,10 @@ static int really_probe_debug(struct device *dev, struct device_driver *drv)
  */
 int driver_probe_done(void)
 {
-	pr_debug("%s: probe_count = %d\n", __func__,
-		 atomic_read(&probe_count));
-	if (atomic_read(&probe_count))
+	int local_probe_count = atomic_read(&probe_count);
+
+	pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
+	if (local_probe_count)
 		return -EBUSY;
 	return 0;
 }