diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2013-09-23 19:04:26 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-09-25 14:07:55 +0200 |
| commit | a233f1120c37724938f7201fe2353b2577adaaf9 (patch) | |
| tree | 9d7b0887b3398a1fc699ea557822c891bf9c450d /kernel/sched | |
| parent | bdb43806589096ac4272fe1307e789846ac08d7c (diff) | |
sched: Prepare for per-cpu preempt_count
When using per-cpu preempt_count variables we need to save/restore the
preempt_count on context switch (into per task storage; for instance
the old thread_info::preempt_count variable) because of
PREEMPT_ACTIVE.
However, this means that on fork() the preempt_count value of the last
context switch gets copied and if we had a PREEMPT_ACTIVE switch right
before cloning a child task the child task will now too have
PREEMPT_ACTIVE set and start its life with an extra PREEMPT_ACTIVE
count.
Therefore we need to make init_task_preempt_count() unconditional;
this resets whatever preempt_count we inherited from our parent
process.
Doing so for !per-cpu implementations is harmless.
For !PREEMPT_COUNT kernels we need to be careful not to start life
with an increased preempt_count.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-4k0b7oy1rcdyzochwiixuwi9@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9c84a9ab189..f575d5bd7e7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1722,9 +1722,7 @@ void sched_fork(struct task_struct *p) #if defined(CONFIG_SMP) p->on_cpu = 0; #endif -#ifdef CONFIG_PREEMPT_COUNT init_task_preempt_count(p); -#endif #ifdef CONFIG_SMP plist_node_init(&p->pushable_tasks, MAX_PRIO); #endif |