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authorIngo Molnar <mingo@elte.hu>2007-12-07 19:02:47 +0100
committerIngo Molnar <mingo@elte.hu>2007-12-07 19:02:47 +0100
commit8ced5f69e4bc09adcc6442e090e2e64c197246cf (patch)
treed431ff185719579c6a786a97adf6def6a849751c /kernel/sched.c
parent5f9fa8a62d6a98f5cb2ee2e00b85bfe95e45888d (diff)
downloadlwn-8ced5f69e4bc09adcc6442e090e2e64c197246cf.tar.gz
lwn-8ced5f69e4bc09adcc6442e090e2e64c197246cf.zip
sched: enable early use of sched_clock()
some platforms have sched_clock() implementations that cannot be called very early during wakeup. If it's called it might hang or crash in hard to debug ways. So only call update_rq_clock() [which calls sched_clock()] if sched_init() has already been called. (rq->idle is NULL before the scheduler is initialized.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 67d9d1799d86..c6e551de795b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -488,7 +488,12 @@ unsigned long long cpu_clock(int cpu)
local_irq_save(flags);
rq = cpu_rq(cpu);
- update_rq_clock(rq);
+ /*
+ * Only call sched_clock() if the scheduler has already been
+ * initialized (some code might call cpu_clock() very early):
+ */
+ if (rq->idle)
+ update_rq_clock(rq);
now = rq->clock;
local_irq_restore(flags);