patch-2.4.2 linux/include/asm-s390x/semaphore-helper.h

• Lines: 101
• Date: Tue Feb 13 14:13:44 2001
• Orig file: v2.4.1/linux/include/asm-s390x/semaphore-helper.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.1/linux/include/asm-s390x/semaphore-helper.h linux/include/asm-s390x/semaphore-helper.h
@@ -0,0 +1,100 @@
+/*
+ *  include/asm-s390/semaphore-helper.h
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *
+ *  Derived from "include/asm-i386/semaphore-helper.h"
+ *    (C) Copyright 1996 Linus Torvalds
+ *    (C) Copyright 1999 Andrea Arcangeli
+ */
+
+#ifndef _S390_SEMAPHORE_HELPER_H
+#define _S390_SEMAPHORE_HELPER_H
+
+/*
+ * These two _must_ execute atomically wrt each other.
+ *
+ * This is trivially done with load_locked/store_cond,
+ * but on the x86 we need an external synchronizer.
+ */
+static inline void wake_one_more(struct semaphore * sem)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&semaphore_wake_lock, flags);
+	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
+ *
+ * If we give up we must undo our count-decrease we previously did in down().
+ * Subtle: up() can continue to happens and increase the semaphore count
+ * even during our critical section protected by the spinlock. So
+ * we must remeber to undo the sem->waking that will be run from
+ * wake_one_more() some time soon, if the semaphore count become > 0.
+ */
+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)) {
+               if (atomic_inc_and_test_greater_zero(&sem->count))
+                       sem->waking--;
+		ret = -EINTR;
+	}
+	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
+	return ret;
+}
+
+/*
+ * waking_non_zero_trylock:
+ *	1	failed to lock
+ *	0	got the lock
+ *
+ * Implementation details are the same of the interruptible case.
+ */
+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)
+        {
+                if (atomic_inc_and_test_greater_zero(&sem->count))
+                        sem->waking--;
+        } else {
+		sem->waking--;
+		ret = 0;
+	}
+	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
+	return ret;
+}
+
+#endif