Add early-boot-safety check to cond_resched()

Just to be safe, we should not trigger a conditional reschedule during
the early boot sequence.  We've historically done some questionable
early on, and the safety warnings in __might_sleep() are generally
turned off during that period, so there might be problems lurking.

This affects CONFIG_PREEMPT_VOLUNTARY, which takes over might_sleep() to
cause a voluntary conditional reschedule.

Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 12d291bf3379..3454bb869fd0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4028,6 +4028,8 @@ static inline void __cond_resched(void)
          */
         if (unlikely(preempt_count()))
                 return;
+        if (unlikely(system_state != SYSTEM_RUNNING))
+                return;
         do {
                 add_preempt_count(PREEMPT_ACTIVE);
                 schedule();