From ce58ae6f7f6bdd48c87472ff830a6d586ff076b2 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Fri, 12 Jun 2009 10:26:22 +0200
Subject: [PATCH] [S390] implement interrupt-enabling rwlocks

arch backend for f5f7eac41db827a47b2163330eecd7bb55ae9f12
"Allow rwlocks to re-enable interrupts".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/include/asm/spinlock.h | 19 ++++++++++++---
 arch/s390/lib/spinlock.c         | 40 ++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h
index f3861b09ebb0..c9af0d19c7ab 100644
--- a/arch/s390/include/asm/spinlock.h
+++ b/arch/s390/include/asm/spinlock.h
@@ -122,8 +122,10 @@ static inline void __raw_spin_unlock(raw_spinlock_t *lp)
 #define __raw_write_can_lock(x) ((x)->lock == 0)
 
 extern void _raw_read_lock_wait(raw_rwlock_t *lp);
+extern void _raw_read_lock_wait_flags(raw_rwlock_t *lp, unsigned long flags);
 extern int _raw_read_trylock_retry(raw_rwlock_t *lp);
 extern void _raw_write_lock_wait(raw_rwlock_t *lp);
+extern void _raw_write_lock_wait_flags(raw_rwlock_t *lp, unsigned long flags);
 extern int _raw_write_trylock_retry(raw_rwlock_t *lp);
 
 static inline void __raw_read_lock(raw_rwlock_t *rw)
@@ -134,6 +136,14 @@ static inline void __raw_read_lock(raw_rwlock_t *rw)
 		_raw_read_lock_wait(rw);
 }
 
+static inline void __raw_read_lock_flags(raw_rwlock_t *rw, unsigned long flags)
+{
+	unsigned int old;
+	old = rw->lock & 0x7fffffffU;
+	if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
+		_raw_read_lock_wait_flags(rw, flags);
+}
+
 static inline void __raw_read_unlock(raw_rwlock_t *rw)
 {
 	unsigned int old, cmp;
@@ -151,6 +161,12 @@ static inline void __raw_write_lock(raw_rwlock_t *rw)
 		_raw_write_lock_wait(rw);
 }
 
+static inline void __raw_write_lock_flags(raw_rwlock_t *rw, unsigned long flags)
+{
+	if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
+		_raw_write_lock_wait_flags(rw, flags);
+}
+
 static inline void __raw_write_unlock(raw_rwlock_t *rw)
 {
 	_raw_compare_and_swap(&rw->lock, 0x80000000, 0);
@@ -172,9 +188,6 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
 	return _raw_write_trylock_retry(rw);
 }
 
-#define __raw_read_lock_flags(lock, flags) __raw_read_lock(lock)
-#define __raw_write_lock_flags(lock, flags) __raw_write_lock(lock)
-
 #define _raw_read_relax(lock)	cpu_relax()
 #define _raw_write_relax(lock)	cpu_relax()
 
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index e41f4008afc5..f7e0d30250b7 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -124,6 +124,27 @@ void _raw_read_lock_wait(raw_rwlock_t *rw)
 }
 EXPORT_SYMBOL(_raw_read_lock_wait);
 
+void _raw_read_lock_wait_flags(raw_rwlock_t *rw, unsigned long flags)
+{
+	unsigned int old;
+	int count = spin_retry;
+
+	local_irq_restore(flags);
+	while (1) {
+		if (count-- <= 0) {
+			_raw_yield();
+			count = spin_retry;
+		}
+		if (!__raw_read_can_lock(rw))
+			continue;
+		old = rw->lock & 0x7fffffffU;
+		local_irq_disable();
+		if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
+			return;
+	}
+}
+EXPORT_SYMBOL(_raw_read_lock_wait_flags);
+
 int _raw_read_trylock_retry(raw_rwlock_t *rw)
 {
 	unsigned int old;
@@ -157,6 +178,25 @@ void _raw_write_lock_wait(raw_rwlock_t *rw)
 }
 EXPORT_SYMBOL(_raw_write_lock_wait);
 
+void _raw_write_lock_wait_flags(raw_rwlock_t *rw, unsigned long flags)
+{
+	int count = spin_retry;
+
+	local_irq_restore(flags);
+	while (1) {
+		if (count-- <= 0) {
+			_raw_yield();
+			count = spin_retry;
+		}
+		if (!__raw_write_can_lock(rw))
+			continue;
+		local_irq_disable();
+		if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
+			return;
+	}
+}
+EXPORT_SYMBOL(_raw_write_lock_wait_flags);
+
 int _raw_write_trylock_retry(raw_rwlock_t *rw)
 {
 	int count = spin_retry;