1 files changed, 84 insertions, 0 deletions

diff --git a/include/asm-arm/semaphore-helper.h b/include/asm-arm/semaphore-helper.h
new file mode 100644
index 000000000000..1d7f1987edb9
--- /dev/null
+++ b/include/asm-arm/semaphore-helper.h
@@ -0,0 +1,84 @@
+#ifndef ASMARM_SEMAPHORE_HELPER_H
+#define ASMARM_SEMAPHORE_HELPER_H
+
+/*
+ * These two _must_ execute atomically wrt each other.
+ */
+static inline void wake_one_more(struct semaphore * sem)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&semaphore_wake_lock, flags);
+        if (atomic_read(&sem->count) <= 0)
+                sem->waking++;
+        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
+}
+
+static inline int waking_non_zero(struct semaphore *sem)
+{
+        unsigned long flags;
+        int ret = 0;
+
+        spin_lock_irqsave(&semaphore_wake_lock, flags);
+        if (sem->waking > 0) {
+                sem->waking--;
+                ret = 1;
+        }
+        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
+        return ret;
+}
+
+/*
+ * waking non zero interruptible
+ *      1       got the lock
+ *      0       go to sleep
+ *      -EINTR  interrupted
+ *
+ * We must undo the sem->count down_interruptible() increment while we are
+ * protected by the spinlock in order to make this atomic_inc() with the
+ * atomic_read() in wake_one_more(), otherwise we can race. -arca
+ */
+static inline int waking_non_zero_interruptible(struct semaphore *sem,
+                                                struct task_struct *tsk)
+{
+        unsigned long flags;
+        int ret = 0;
+
+        spin_lock_irqsave(&semaphore_wake_lock, flags);
+        if (sem->waking > 0) {
+                sem->waking--;
+                ret = 1;
+        } else if (signal_pending(tsk)) {
+                atomic_inc(&sem->count);
+                ret = -EINTR;
+        }
+        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
+        return ret;     
+}
+
+/*
+ * waking_non_zero_try_lock:
+ *      1       failed to lock
+ *      0       got the lock
+ *
+ * We must undo the sem->count down_interruptible() increment while we are
+ * protected by the spinlock in order to make this atomic_inc() with the
+ * atomic_read() in wake_one_more(), otherwise we can race. -arca
+ */
+static inline int waking_non_zero_trylock(struct semaphore *sem)
+{
+        unsigned long flags;
+        int ret = 1;
+
+        spin_lock_irqsave(&semaphore_wake_lock, flags);
+        if (sem->waking <= 0)
+                atomic_inc(&sem->count);
+        else {
+                sem->waking--;
+                ret = 0;
+        }
+        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
+        return ret;
+}
+
+#endif