linux-kernel - [PATCH v2 1/2] preempt: Move PREEMPT_NEED

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Message-Id: <1543599271-14339-2-git-send-email-will.deacon@arm.com>
Date:   Fri, 30 Nov 2018 17:34:30 +0000
From:   Will Deacon <will.deacon@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, ard.biesheuvel@...aro.org,
        catalin.marinas@....com, rml@...h9.net, tglx@...utronix.de,
        peterz@...radead.org, schwidefsky@...ibm.com,
        Will Deacon <will.deacon@....com>
Subject: [PATCH v2 1/2] preempt: Move PREEMPT_NEED_RESCHED definition into arch code

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@...h9.net>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Will Deacon <will.deacon@....com>
---
 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