[PATCH] x86_64: Remove asm-x86_64/rwsem.h

Not needed since x86-64 always uses the spinlock based rwsems.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-x86_64/rwsem.h

@@ -1,283 +0,0 @@
-/* rwsem.h: R/W semaphores implemented using XADD/CMPXCHG for x86_64+
- *
- * Written by David Howells (dhowells@redhat.com).
- * Ported by Andi Kleen <ak@suse.de> to x86-64.
- *
- * Derived from asm-i386/semaphore.h and asm-i386/rwsem.h
- *
- *
- * The MSW of the count is the negated number of active writers and waiting
- * lockers, and the LSW is the total number of active locks
- *
- * The lock count is initialized to 0 (no active and no waiting lockers).
- *
- * When a writer subtracts WRITE_BIAS, it'll get 0xffff0001 for the case of an
- * uncontended lock. This can be determined because XADD returns the old value.
- * Readers increment by 1 and see a positive value when uncontended, negative
- * if there are writers (and maybe) readers waiting (in which case it goes to
- * sleep).
- *
- * The value of WAITING_BIAS supports up to 32766 waiting processes. This can
- * be extended to 65534 by manually checking the whole MSW rather than relying
- * on the S flag.
- *
- * The value of ACTIVE_BIAS supports up to 65535 active processes.
- *
- * This should be totally fair - if anything is waiting, a process that wants a
- * lock will go to the back of the queue. When the currently active lock is
- * released, if there's a writer at the front of the queue, then that and only
- * that will be woken up; if there's a bunch of consecutive readers at the
- * front, then they'll all be woken up, but no other readers will be.
- */
-
-#ifndef _X8664_RWSEM_H
-#define _X8664_RWSEM_H
-
-#ifndef _LINUX_RWSEM_H
-#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
-#endif
-
-#ifdef __KERNEL__
-
-#include <linux/list.h>
-#include <linux/spinlock.h>
-
-struct rwsem_waiter;
-
-extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *);
-extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
-
-/*
- * the semaphore definition
- */
-struct rw_semaphore {
-	signed int		count;
-#define RWSEM_UNLOCKED_VALUE		0x00000000
-#define RWSEM_ACTIVE_BIAS		0x00000001
-#define RWSEM_ACTIVE_MASK		0x0000ffff
-#define RWSEM_WAITING_BIAS		(-0x00010000)
-#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
-#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
-	spinlock_t		wait_lock;
-	struct list_head	wait_list;
-#if RWSEM_DEBUG
-	int			debug;
-#endif
-};
-
-/*
- * initialisation
- */
-#if RWSEM_DEBUG
-#define __RWSEM_DEBUG_INIT      , 0
-#else
-#define __RWSEM_DEBUG_INIT	/* */
-#endif
-
-#define __RWSEM_INITIALIZER(name) \
-{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) \
-	__RWSEM_DEBUG_INIT }
-
-#define DECLARE_RWSEM(name) \
-	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
-
-static inline void init_rwsem(struct rw_semaphore *sem)
-{
-	sem->count = RWSEM_UNLOCKED_VALUE;
-	spin_lock_init(&sem->wait_lock);
-	INIT_LIST_HEAD(&sem->wait_list);
-#if RWSEM_DEBUG
-	sem->debug = 0;
-#endif
-}
-
-/*
- * lock for reading
- */
-static inline void __down_read(struct rw_semaphore *sem)
-{
-	__asm__ __volatile__(
-		"# beginning down_read\n\t"
-LOCK_PREFIX	"  incl      (%%rdi)\n\t" /* adds 0x00000001, returns the old value */
-		"  js        2f\n\t" /* jump if we weren't granted the lock */
-		"1:\n\t"
-		LOCK_SECTION_START("") \
-		"2:\n\t"
-		"  call      rwsem_down_read_failed_thunk\n\t"
-		"  jmp       1b\n"
-		LOCK_SECTION_END \
-		"# ending down_read\n\t"
-		: "+m"(sem->count)
-		: "D"(sem)
-		: "memory", "cc");
-}
-
-
-/*
- * trylock for reading -- returns 1 if successful, 0 if contention
- */
-static inline int __down_read_trylock(struct rw_semaphore *sem)
-{
-	__s32 result, tmp;
-	__asm__ __volatile__(
-		"# beginning __down_read_trylock\n\t"
-		"  movl      %0,%1\n\t"
-		"1:\n\t"
-		"  movl	     %1,%2\n\t"
-		"  addl      %3,%2\n\t"
-		"  jle	     2f\n\t"
-LOCK_PREFIX	"  cmpxchgl  %2,%0\n\t"
-		"  jnz	     1b\n\t"
-		"2:\n\t"
-		"# ending __down_read_trylock\n\t"
-		: "+m"(sem->count), "=&a"(result), "=&r"(tmp)
-		: "i"(RWSEM_ACTIVE_READ_BIAS)
-		: "memory", "cc");
-	return result>=0 ? 1 : 0;
-}
-
-
-/*
- * lock for writing
- */
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	int tmp;
-
-	tmp = RWSEM_ACTIVE_WRITE_BIAS;
-	__asm__ __volatile__(
-		"# beginning down_write\n\t"
-LOCK_PREFIX	"  xaddl      %0,(%%rdi)\n\t" /* subtract 0x0000ffff, returns the old value */
-		"  testl     %0,%0\n\t" /* was the count 0 before? */
-		"  jnz       2f\n\t" /* jump if we weren't granted the lock */
-		"1:\n\t"
-		LOCK_SECTION_START("")
-		"2:\n\t"
-		"  call      rwsem_down_write_failed_thunk\n\t"
-		"  jmp       1b\n"
-		LOCK_SECTION_END
-		"# ending down_write"
-		: "=&r" (tmp) 
-		: "0"(tmp), "D"(sem)
-		: "memory", "cc");
-}
-
-/*
- * trylock for writing -- returns 1 if successful, 0 if contention
- */
-static inline int __down_write_trylock(struct rw_semaphore *sem)
-{
-	signed long ret = cmpxchg(&sem->count,
-				  RWSEM_UNLOCKED_VALUE, 
-				  RWSEM_ACTIVE_WRITE_BIAS);
-	if (ret == RWSEM_UNLOCKED_VALUE)
-		return 1;
-	return 0;
-}
-
-/*
- * unlock after reading
- */
-static inline void __up_read(struct rw_semaphore *sem)
-{
-	__s32 tmp = -RWSEM_ACTIVE_READ_BIAS;
-	__asm__ __volatile__(
-		"# beginning __up_read\n\t"
-LOCK_PREFIX	"  xaddl      %[tmp],(%%rdi)\n\t" /* subtracts 1, returns the old value */
-		"  js        2f\n\t" /* jump if the lock is being waited upon */
-		"1:\n\t"
-		LOCK_SECTION_START("")
-		"2:\n\t"
-		"  decw      %w[tmp]\n\t" /* do nothing if still outstanding active readers */
-		"  jnz       1b\n\t"
-		"  call      rwsem_wake_thunk\n\t"
-		"  jmp       1b\n"
-		LOCK_SECTION_END
-		"# ending __up_read\n"
-		: "+m"(sem->count), [tmp] "+r" (tmp)
-		: "D"(sem)
-		: "memory", "cc");
-}
-
-/*
- * unlock after writing
- */
-static inline void __up_write(struct rw_semaphore *sem)
-{
-	unsigned tmp; 
-	__asm__ __volatile__(
-		"# beginning __up_write\n\t"
-		"  movl     %[bias],%[tmp]\n\t"
-LOCK_PREFIX	"  xaddl     %[tmp],(%%rdi)\n\t" /* tries to transition 0xffff0001 -> 0x00000000 */
-		"  jnz       2f\n\t" /* jump if the lock is being waited upon */
-		"1:\n\t"
-		LOCK_SECTION_START("")
-		"2:\n\t"
-		"  decw      %w[tmp]\n\t" /* did the active count reduce to 0? */
-		"  jnz       1b\n\t" /* jump back if not */
-		"  call      rwsem_wake_thunk\n\t"
-		"  jmp       1b\n"
-		LOCK_SECTION_END
-		"# ending __up_write\n"
-		: "+m"(sem->count), [tmp] "=r" (tmp)
-		: "D"(sem), [bias] "i"(-RWSEM_ACTIVE_WRITE_BIAS)
-		: "memory", "cc");
-}
-
-/*
- * downgrade write lock to read lock
- */
-static inline void __downgrade_write(struct rw_semaphore *sem)
-{
-	__asm__ __volatile__(
-		"# beginning __downgrade_write\n\t"
-LOCK_PREFIX	"  addl      %[bias],(%%rdi)\n\t" /* transitions 0xZZZZ0001 -> 0xYYYY0001 */
-		"  js        2f\n\t" /* jump if the lock is being waited upon */
-		"1:\n\t"
-		LOCK_SECTION_START("")
-		"2:\n\t"
-		"  call	     rwsem_downgrade_thunk\n"
-		"  jmp       1b\n"
-		LOCK_SECTION_END
-		"# ending __downgrade_write\n"
-		: "=m"(sem->count)
-		: "D"(sem), [bias] "i"(-RWSEM_WAITING_BIAS), "m"(sem->count)
-		: "memory", "cc");
-}
-
-/*
- * implement atomic add functionality
- */
-static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
-{
-	__asm__ __volatile__(
-LOCK_PREFIX	"addl %1,%0"
-		:"=m"(sem->count)
-		:"ir"(delta), "m"(sem->count));
-}
-
-/*
- * implement exchange and add functionality
- */
-static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
-{
-	int tmp = delta;
-
-	__asm__ __volatile__(
-LOCK_PREFIX	"xaddl %0,(%2)"
-		: "=r"(tmp), "=m"(sem->count)
-		: "r"(sem), "m"(sem->count), "0" (tmp)
-		: "memory");
-
-	return tmp+delta;
-}
-
-static inline int rwsem_is_locked(struct rw_semaphore *sem)
-{
-	return (sem->count != 0);
-}
-
-#endif /* __KERNEL__ */
-#endif /* _X8664_RWSEM_H */