[PATCH 1/2] preempt: Move PREEMPT_NEED_RESCHED definition into arch code

From: Will Deacon
Date: Tue Nov 27 2018 - 14:44:53 EST


PREEMPT_NEED_RESCHED is never used directly, so move it into the arch
code where it can potentially be implemented using either a different
bit in the preempt count or as an entirely separate entity.

Cc: Robert Love <rml@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
---
arch/s390/include/asm/preempt.h | 2 ++
arch/x86/include/asm/preempt.h | 3 +++
include/linux/preempt.h | 3 ---
3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/preempt.h b/arch/s390/include/asm/preempt.h
index 23a14d187fb1..b5ea9e14c017 100644
--- a/arch/s390/include/asm/preempt.h
+++ b/arch/s390/include/asm/preempt.h
@@ -8,6 +8,8 @@

#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES

+/* We use the MSB mostly because its available */
+#define PREEMPT_NEED_RESCHED 0x80000000
#define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)

static inline int preempt_count(void)
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 90cb2f36c042..99a7fa9ab0a3 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -8,6 +8,9 @@

DECLARE_PER_CPU(int, __preempt_count);

+/* We use the MSB mostly because its available */
+#define PREEMPT_NEED_RESCHED 0x80000000
+
/*
* We use the PREEMPT_NEED_RESCHED bit as an inverted NEED_RESCHED such
* that a decrement hitting 0 means we can and should reschedule.
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index c01813c3fbe9..dd92b1a93919 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -53,9 +53,6 @@

#define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET)

-/* We use the MSB mostly because its available */
-#define PREEMPT_NEED_RESCHED 0x80000000
-
#define PREEMPT_DISABLED (PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED)

/*
--
2.1.4