diff options
| -rw-r--r-- | kernel/sched/core.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e6910526c84b..4a42f8299ac8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2358,13 +2358,20 @@ 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); |