diff options
| author | Ingo Molnar <mingo@elte.hu> | 2008-02-13 14:02:36 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-02-25 16:34:16 +0100 |
| commit | 6892b75e60557a48c01d57ba320419a9e2ce9846 (patch) | |
| tree | 2ba5c725d4723385e88b0a54e8bb4be5b9e38384 /kernel | |
| parent | Linux 2.6.25-rc3 (diff) | |
| download | linux-6892b75e60557a48c01d57ba320419a9e2ce9846.tar.xz linux-6892b75e60557a48c01d57ba320419a9e2ce9846.zip | |
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 <tony.luck@gmail.com>
Acked-by: Tony Luck <tony.luck@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index b387a8de26a5..7286ccb01082 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 |