diff -ur v2.4.2-pre3/include/asm-i386/semaphore.h trylock/include/asm-i386/semaphore.h
--- v2.4.2-pre3/include/asm-i386/semaphore.h	Mon Feb 12 16:04:59 2001
+++ trylock/include/asm-i386/semaphore.h	Mon Feb 19 23:50:03 2001
@@ -382,5 +382,32 @@
 	__up_write(sem);
 }
 
+/* returns 1 if it successfully obtained the semaphore for write */
+static inline int down_write_trylock(struct rw_semaphore *sem)
+{
+	int old = RW_LOCK_BIAS, new = 0;
+	int res;
+
+	res = cmpxchg(&sem->count.counter, old, new);
+	return (res == RW_LOCK_BIAS);
+}
+
+/* returns 1 if it successfully obtained the semaphore for read */
+static inline int down_read_trylock(struct rw_semaphore *sem)
+{
+	int ret = 1;
+	asm volatile(
+		LOCK "subl $1,%0
+		js 2f
+	1:
+		.section .text.lock,\"ax\"
+	2:"	LOCK "inc %0
+		subl %1,%1
+		jmp 1b
+		.previous"
+		:"=m" (*(volatile int *)sem), "=r" (ret) : "1" (ret) : "memory");
+	return ret;
+}
+
 #endif
 #endif