From 91cdb1615815f85a595207a94cfe0cd4405964a8 Mon Sep 17 00:00:00 2001
From: Balazs Gerofi <bgerofi@riken.jp>
Date: Sat, 17 Dec 2016 13:44:27 +0900
Subject: [PATCH] MCS lock: separate IRQ disable/enable versions

---
 arch/x86/kernel/include/arch-lock.h | 34 +++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/include/arch-lock.h b/arch/x86/kernel/include/arch-lock.h
index ff4437af..29b3e19d 100644
--- a/arch/x86/kernel/include/arch-lock.h
+++ b/arch/x86/kernel/include/arch-lock.h
@@ -131,6 +131,7 @@ static void __ihk_mc_spinlock_unlock(ihk_spinlock_t *lock, unsigned long flags)
 typedef struct mcs_lock_node {
 	unsigned long locked;
 	struct mcs_lock_node *next;
+	unsigned long irqsave;
 } __attribute__((aligned(64))) mcs_lock_node_t;
 
 static void mcs_lock_init(struct mcs_lock_node *node)
@@ -139,7 +140,7 @@ static void mcs_lock_init(struct mcs_lock_node *node)
 	node->next = NULL;
 }
 
-static void mcs_lock_lock(struct mcs_lock_node *lock,
+static void __mcs_lock_lock(struct mcs_lock_node *lock,
 		struct mcs_lock_node *node)
 {
 	struct mcs_lock_node *pred;
@@ -158,7 +159,7 @@ static void mcs_lock_lock(struct mcs_lock_node *lock,
 	}
 }
 
-static void mcs_lock_unlock(struct mcs_lock_node *lock,
+static void __mcs_lock_unlock(struct mcs_lock_node *lock,
 		struct mcs_lock_node *node)
 {
 	if (node->next == NULL) {
@@ -178,6 +179,35 @@ static void mcs_lock_unlock(struct mcs_lock_node *lock,
 	node->next->locked = 0;
 }
 
+static void mcs_lock_lock_noirq(struct mcs_lock_node *lock,
+		struct mcs_lock_node *node)
+{
+	preempt_disable();
+	__mcs_lock_lock(lock, node);
+}
+
+static void mcs_lock_unlock_noirq(struct mcs_lock_node *lock,
+		struct mcs_lock_node *node)
+{
+	__mcs_lock_unlock(lock, node);
+	preempt_enable();
+}
+
+static void mcs_lock_lock(struct mcs_lock_node *lock,
+		struct mcs_lock_node *node)
+{
+	node->irqsave = cpu_disable_interrupt_save();
+	mcs_lock_lock_noirq(lock, node);
+}
+
+static void mcs_lock_unlock(struct mcs_lock_node *lock,
+		struct mcs_lock_node *node)
+{
+	mcs_lock_unlock_noirq(lock, node);
+	cpu_restore_interrupt(node->irqsave);
+}
+
+
 // reader/writer lock
 typedef struct mcs_rwlock_node {
 	ihk_atomic_t count;	// num of readers (use only common reader)