Merge remote-tracking branches 'regulator/fix/anatop', 'regulator/fix/gpio', 'regulat...

[firefly-linux-kernel-4.4.55.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 97d276ff1edb1225f0ad894cb66b052be36b2104..2f9c9288481779c309f31c19dc3b74831ef70b3d 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2669,13 +2669,20 @@ unsigned long nr_running(void)
 
 /*
  * Check if only the current task is running on the cpu.
+ *
+ * Caution: this function does not check that the caller has disabled
+ * preemption, thus the result might have a time-of-check-to-time-of-use
+ * race.  The caller is responsible to use it correctly, for example:
+ *
+ * - from a non-preemptable section (of course)
+ *
+ * - from a thread that is bound to a single CPU
+ *
+ * - in a loop with very short iterations (e.g. a polling loop)
  */
 bool single_task_running(void)
 {
-       if (cpu_rq(smp_processor_id())->nr_running == 1)
-               return true;
-       else
-               return false;
+       return raw_rq()->nr_running == 1;
 }
 EXPORT_SYMBOL(single_task_running);