sched/rt: Document scheduler related skip-resched-check sites
Create a distinction between scheduler related preempt_enable_no_resched()
calls and the nearly one hundred other places in the kernel that do not
want to reschedule, for one reason or another.
This distinction matters for -rt, where the scheduler and the non-scheduler
preempt models (and checks) are different. For upstream it's purely
documentational.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/tip-gs88fvx2mdv5psnzxnv575ke@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 6503514..c97fc60 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -102,7 +102,7 @@
rcu_idle_exit();
tick_nohz_idle_exit();
if (cpu_should_die()) {
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
cpu_die();
}
schedule_preempt_disabled();
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index ab9a292..06b5b5f 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -106,7 +106,7 @@
#ifdef CONFIG_HOTPLUG_CPU
if (cpu_is_offline(cpu)) {
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
cpu_play_dead();
}
#endif
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 58969b2..5a710b9 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -48,12 +48,14 @@
barrier(); \
} while (0)
-#define preempt_enable_no_resched() \
+#define sched_preempt_enable_no_resched() \
do { \
barrier(); \
dec_preempt_count(); \
} while (0)
+#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
+
#define preempt_enable() \
do { \
preempt_enable_no_resched(); \
@@ -92,6 +94,7 @@
#else /* !CONFIG_PREEMPT_COUNT */
#define preempt_disable() do { } while (0)
+#define sched_preempt_enable_no_resched() do { } while (0)
#define preempt_enable_no_resched() do { } while (0)
#define preempt_enable() do { } while (0)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7302239..643cc37 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3220,7 +3220,7 @@
post_schedule(rq);
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
if (need_resched())
goto need_resched;
}
@@ -3253,7 +3253,7 @@
*/
void __sched schedule_preempt_disabled(void)
{
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
schedule();
preempt_disable();
}
@@ -4486,7 +4486,7 @@
__release(rq->lock);
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
do_raw_spin_unlock(&rq->lock);
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
schedule();
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 79b5247..f268369 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -353,7 +353,7 @@
tick_nohz_irq_exit();
#endif
rcu_irq_exit();
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
}
/*
@@ -759,7 +759,7 @@
if (local_softirq_pending())
__do_softirq();
local_irq_enable();
- preempt_enable_no_resched();
+ sched_preempt_enable_no_resched();
cond_resched();
preempt_disable();
rcu_note_context_switch((long)__bind_cpu);