[RFC][PATCH 07/11] sched: Stop setting PREEMPT_ACTIVE

From: Peter Zijlstra
Date: Tue Sep 29 2015 - 05:43:18 EST


Now that nothing tests for PREEMPT_ACTIVE anymore, stop setting it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
include/linux/preempt.h | 12 ------------
kernel/sched/core.c | 19 ++++++-------------
2 files changed, 6 insertions(+), 25 deletions(-)

--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -146,18 +146,6 @@ extern void preempt_count_sub(int val);
#define preempt_count_inc() preempt_count_add(1)
#define preempt_count_dec() preempt_count_sub(1)

-#define preempt_active_enter() \
-do { \
- preempt_count_add(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
- barrier(); \
-} while (0)
-
-#define preempt_active_exit() \
-do { \
- barrier(); \
- preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
-} while (0)
-
#ifdef CONFIG_PREEMPT_COUNT

#define preempt_disable() \
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3190,9 +3190,9 @@ void __sched schedule_preempt_disabled(v
static void __sched notrace preempt_schedule_common(void)
{
do {
- preempt_active_enter();
+ preempt_disable();
__schedule(true);
- preempt_active_exit();
+ sched_preempt_enable_no_resched();

/*
* Check again in case we missed a preemption opportunity
@@ -3243,13 +3243,7 @@ asmlinkage __visible void __sched notrac
return;

do {
- /*
- * Use raw __prempt_count() ops that don't call function.
- * We can't call functions before disabling preemption which
- * disarm preemption tracing recursions.
- */
- __preempt_count_add(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET);
- barrier();
+ preempt_disable_notrace();
/*
* Needs preempt disabled in case user_exit() is traced
* and the tracer calls preempt_enable_notrace() causing
@@ -3259,8 +3253,7 @@ asmlinkage __visible void __sched notrac
__schedule(true);
exception_exit(prev_ctx);

- barrier();
- __preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET);
+ preempt_enable_no_resched_notrace();
} while (need_resched());
}
EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
@@ -3283,11 +3276,11 @@ asmlinkage __visible void __sched preemp
prev_state = exception_enter();

do {
- preempt_active_enter();
+ preempt_disable();
local_irq_enable();
__schedule(true);
local_irq_disable();
- preempt_active_exit();
+ sched_preempt_enable_no_resched();
} while (need_resched());

exception_exit(prev_state);


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