From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001
From: root <root@artemis.panaceas.org>
Date: Fri, 25 Dec 2015 04:40:36 +0000
Subject: initial_commit

---
 arch/alpha/lib/dec_and_lock.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 arch/alpha/lib/dec_and_lock.c

(limited to 'arch/alpha/lib/dec_and_lock.c')

diff --git a/arch/alpha/lib/dec_and_lock.c b/arch/alpha/lib/dec_and_lock.c
new file mode 100644
index 00000000..0f5520d2
--- /dev/null
+++ b/arch/alpha/lib/dec_and_lock.c
@@ -0,0 +1,41 @@
+/*
+ * arch/alpha/lib/dec_and_lock.c
+ *
+ * ll/sc version of atomic_dec_and_lock()
+ * 
+ */
+
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+
+  asm (".text					\n\
+	.global _atomic_dec_and_lock		\n\
+	.ent _atomic_dec_and_lock		\n\
+	.align	4				\n\
+_atomic_dec_and_lock:				\n\
+	.prologue 0				\n\
+1:	ldl_l	$1, 0($16)			\n\
+	subl	$1, 1, $1			\n\
+	beq	$1, 2f				\n\
+	stl_c	$1, 0($16)			\n\
+	beq	$1, 4f				\n\
+	mb					\n\
+	clr	$0				\n\
+	ret					\n\
+2:	br	$29, 3f				\n\
+3:	ldgp	$29, 0($29)			\n\
+	br	$atomic_dec_and_lock_1..ng	\n\
+	.subsection 2				\n\
+4:	br	1b				\n\
+	.previous				\n\
+	.end _atomic_dec_and_lock");
+
+static int __used atomic_dec_and_lock_1(atomic_t *atomic, spinlock_t *lock)
+{
+	/* Slow path */
+	spin_lock(lock);
+	if (atomic_dec_and_test(atomic))
+		return 1;
+	spin_unlock(lock);
+	return 0;
+}
-- 
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