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-rw-r--r--arch/alpha/lib/dec_and_lock.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/alpha/lib/dec_and_lock.c b/arch/alpha/lib/dec_and_lock.c
new file mode 100644
index 00000000000..6ae2500a9d9
--- /dev/null
+++ b/arch/alpha/lib/dec_and_lock.c
@@ -0,0 +1,42 @@
+/*
+ * 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 __attribute_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;
+}