Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6892b75e60557a48c01d57ba320419a9e2ce9846
Commit: 6892b75e60557a48c01d57ba320419a9e2ce9846
Parent: bfa274e2436fc7ef72ef51c878083647f1cfd429
Author: Ingo Molnar <[EMAIL PROTECTED]>
AuthorDate: Wed Feb 13 14:02:36 2008 +0100
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Mon Feb 25 16:34:16 2008 +0100
sched: make early bootup sched_clock() use safer
do not call sched_clock() too early. Not only might rq->idle
not be set up - but pure per-cpu data might not be accessible
either.
this solves an ia64 early bootup hang with CONFIG_PRINTK_TIME=y.
Tested-by: Tony Luck <[EMAIL PROTECTED]>
Acked-by: Tony Luck <[EMAIL PROTECTED]>
Acked-by: David S. Miller <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
kernel/sched.c | 14 ++++++++++----
1 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index b387a8d..7286ccb 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -668,6 +668,8 @@ const_debug unsigned int sysctl_sched_nr_migrate = 32;
*/
unsigned int sysctl_sched_rt_period = 1000000;
+static __read_mostly int scheduler_running;
+
/*
* part of the period that we allow rt tasks to run in us.
* default: 0.95s
@@ -689,14 +691,16 @@ unsigned long long cpu_clock(int cpu)
unsigned long flags;
struct rq *rq;
- local_irq_save(flags);
- rq = cpu_rq(cpu);
/*
* 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);
+ if (unlikely(!scheduler_running))
+ return 0;
+
+ local_irq_save(flags);
+ rq = cpu_rq(cpu);
+ update_rq_clock(rq);
now = rq->clock;
local_irq_restore(flags);
@@ -7284,6 +7288,8 @@ void __init sched_init(void)
* During early bootup we pretend to be a normal task:
*/
current->sched_class = &fair_sched_class;
+
+ scheduler_running = 1;
}
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
-
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