patch-2.4.21 linux-2.4.21/include/asm-s390x/rwsem.h

• Lines: 55
• Date: 2003-06-13 07:51:38.000000000 -0700
• Orig file: linux-2.4.20/include/asm-s390x/rwsem.h
• Orig date: 2002-08-02 17:39:45.000000000 -0700

diff -urN linux-2.4.20/include/asm-s390x/rwsem.h linux-2.4.21/include/asm-s390x/rwsem.h
@@ -105,6 +105,27 @@
 }
 
 /*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_read_trylock(struct rw_semaphore *sem)
+{
+	signed long old, new;
+
+	__asm__ __volatile__(
+		"   lg   %0,0(%2)\n"
+		"0: ltgr %1,%0\n"
+		"   jm   1f\n"
+		"   aghi %1,%3\n"
+		"   csg  %0,%1,0(%2)\n"
+		"   jl   0b\n"
+		"1:"
+                : "=&d" (old), "=&d" (new)
+		: "a" (&sem->count), "i" (RWSEM_ACTIVE_READ_BIAS)
+		: "cc", "memory" );
+	return old >= 0 ? 1 : 0;
+}
+
+/*
  * lock for writing
  */
 static inline void __down_write(struct rw_semaphore *sem)
@@ -126,6 +147,26 @@
 }
 
 /*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_write_trylock(struct rw_semaphore *sem)
+{
+	signed long old;
+
+	__asm__ __volatile__(
+		"   lg   %0,0(%1)\n"
+		"0: ltgr %0,%0\n"
+		"   jnz  1f\n"
+		"   csg  %0,%2,0(%1)\n"
+		"   jl   0b\n"
+		"1:"
+                : "=&d" (old)
+		: "a" (&sem->count), "d" (RWSEM_ACTIVE_WRITE_BIAS)
+		: "cc", "memory" );
+	return (old == RWSEM_UNLOCKED_VALUE) ? 1 : 0;
+}
+
+/*
  * unlock after reading
  */
 static inline void __up_read(struct rw_semaphore *sem)