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 000000000000..6ae2500a9d9e
--- /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;
+}