1 files changed, 0 insertions, 284 deletions
diff --git a/lib/rwsem.c b/lib/rwsem.c
deleted file mode 100644
index f236d7cd5cf..00000000000
--- a/lib/rwsem.c
+++ /dev/null
@@ -1,284 +0,0 @@
-/* rwsem.c: R/W semaphores: contention handling functions
- *
- * Written by David Howells (dhowells@redhat.com).
- * Derived from arch/i386/kernel/semaphore.c
- */
-#include <linux/rwsem.h>
-#include <linux/sched.h>
-#include <linux/init.h>
-#include <linux/module.h>
-
-/*
- * Initialize an rwsem:
- */
-void __init_rwsem(struct rw_semaphore *sem, const char *name,
-		  struct lock_class_key *key)
-{
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	/*
-	 * Make sure we are not reinitializing a held semaphore:
-	 */
-	debug_check_no_locks_freed((void *)sem, sizeof(*sem));
-	lockdep_init_map(&sem->dep_map, name, key, 0);
-#endif
-	sem->count = RWSEM_UNLOCKED_VALUE;
-	spin_lock_init(&sem->wait_lock);
-	INIT_LIST_HEAD(&sem->wait_list);
-}
-
-EXPORT_SYMBOL(__init_rwsem);
-
-struct rwsem_waiter {
-	struct list_head list;
-	struct task_struct *task;
-	unsigned int flags;
-#define RWSEM_WAITING_FOR_READ	0x00000001
-#define RWSEM_WAITING_FOR_WRITE	0x00000002
-};
-
-/* Wake types for __rwsem_do_wake().  Note that RWSEM_WAKE_NO_ACTIVE and
- * RWSEM_WAKE_READ_OWNED imply that the spinlock must have been kept held
- * since the rwsem value was observed.
- */
-#define RWSEM_WAKE_ANY        0 /* Wake whatever's at head of wait list */
-#define RWSEM_WAKE_NO_ACTIVE  1 /* rwsem was observed with no active thread */
-#define RWSEM_WAKE_READ_OWNED 2 /* rwsem was observed to be read owned */
-
-/*
- * handle the lock release when processes blocked on it that can now run
- * - if we come here from up_xxxx(), then:
- *   - the 'active part' of count (&0x0000ffff) reached 0 (but may have changed)
- *   - the 'waiting part' of count (&0xffff0000) is -ve (and will still be so)
- * - there must be someone on the queue
- * - the spinlock must be held by the caller
- * - woken process blocks are discarded from the list after having task zeroed
- * - writers are only woken if downgrading is false
- */
-static struct rw_semaphore *
-__rwsem_do_wake(struct rw_semaphore *sem, int wake_type)
-{
-	struct rwsem_waiter *waiter;
-	struct task_struct *tsk;
-	struct list_head *next;
-	signed long oldcount, woken, loop, adjustment;
-
-	waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
-	if (!(waiter->flags & RWSEM_WAITING_FOR_WRITE))
-		goto readers_only;
-
-	if (wake_type == RWSEM_WAKE_READ_OWNED)
-		/* Another active reader was observed, so wakeup is not
-		 * likely to succeed. Save the atomic op.
-		 */
-		goto out;
-
-	/* There's a writer at the front of the queue - try to grant it the
-	 * write lock.  However, we only wake this writer if we can transition
-	 * the active part of the count from 0 -> 1
-	 */
-	adjustment = RWSEM_ACTIVE_WRITE_BIAS;
-	if (waiter->list.next == &sem->wait_list)
-		adjustment -= RWSEM_WAITING_BIAS;
-
- try_again_write:
-	oldcount = rwsem_atomic_update(adjustment, sem) - adjustment;
-	if (oldcount & RWSEM_ACTIVE_MASK)
-		/* Someone grabbed the sem already */
-		goto undo_write;
-
-	/* We must be careful not to touch 'waiter' after we set ->task = NULL.
-	 * It is an allocated on the waiter's stack and may become invalid at
-	 * any time after that point (due to a wakeup from another source).
-	 */
-	list_del(&waiter->list);
-	tsk = waiter->task;
-	smp_mb();
-	waiter->task = NULL;
-	wake_up_process(tsk);
-	put_task_struct(tsk);
-	goto out;
-
- readers_only:
-	/* If we come here from up_xxxx(), another thread might have reached
-	 * rwsem_down_failed_common() before we acquired the spinlock and
-	 * woken up a waiter, making it now active.  We prefer to check for
-	 * this first in order to not spend too much time with the spinlock
-	 * held if we're not going to be able to wake up readers in the end.
-	 *
-	 * Note that we do not need to update the rwsem count: any writer
-	 * trying to acquire rwsem will run rwsem_down_write_failed() due
-	 * to the waiting threads and block trying to acquire the spinlock.
-	 *
-	 * We use a dummy atomic update in order to acquire the cache line
-	 * exclusively since we expect to succeed and run the final rwsem
-	 * count adjustment pretty soon.
-	 */
-	if (wake_type == RWSEM_WAKE_ANY &&
-	    rwsem_atomic_update(0, sem) < RWSEM_WAITING_BIAS)
-		/* Someone grabbed the sem for write already */
-		goto out;
-
-	/* Grant an infinite number of read locks to the readers at the front
-	 * of the queue.  Note we increment the 'active part' of the count by
-	 * the number of readers before waking any processes up.
-	 */
-	woken = 0;
-	do {
-		woken++;
-
-		if (waiter->list.next == &sem->wait_list)
-			break;
-
-		waiter = list_entry(waiter->list.next,
-					struct rwsem_waiter, list);
-
-	} while (waiter->flags & RWSEM_WAITING_FOR_READ);
-
-	adjustment = woken * RWSEM_ACTIVE_READ_BIAS;
-	if (waiter->flags & RWSEM_WAITING_FOR_READ)
-		/* hit end of list above */
-		adjustment -= RWSEM_WAITING_BIAS;
-
-	rwsem_atomic_add(adjustment, sem);
-
-	next = sem->wait_list.next;
-	for (loop = woken; loop > 0; loop--) {
-		waiter = list_entry(next, struct rwsem_waiter, list);
-		next = waiter->list.next;
-		tsk = waiter->task;
-		smp_mb();
-		waiter->task = NULL;
-		wake_up_process(tsk);
-		put_task_struct(tsk);
-	}
-
-	sem->wait_list.next = next;
-	next->prev = &sem->wait_list;
-
- out:
-	return sem;
-
-	/* undo the change to the active count, but check for a transition
-	 * 1->0 */
- undo_write:
-	if (rwsem_atomic_update(-adjustment, sem) & RWSEM_ACTIVE_MASK)
-		goto out;
-	goto try_again_write;
-}
-
-/*
- * wait for a lock to be granted
- */
-static struct rw_semaphore __sched *
-rwsem_down_failed_common(struct rw_semaphore *sem,
-			 unsigned int flags, signed long adjustment)
-{
-	struct rwsem_waiter waiter;
-	struct task_struct *tsk = current;
-	signed long count;
-
-	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
-
-	/* set up my own style of waitqueue */
-	spin_lock_irq(&sem->wait_lock);
-	waiter.task = tsk;
-	waiter.flags = flags;
-	get_task_struct(tsk);
-
-	if (list_empty(&sem->wait_list))
-		adjustment += RWSEM_WAITING_BIAS;
-	list_add_tail(&waiter.list, &sem->wait_list);
-
-	/* we're now waiting on the lock, but no longer actively locking */
-	count = rwsem_atomic_update(adjustment, sem);
-
-	/* If there are no active locks, wake the front queued process(es) up.
-	 *
-	 * Alternatively, if we're called from a failed down_write(), there
-	 * were already threads queued before us and there are no active
-	 * writers, the lock must be read owned; so we try to wake any read
-	 * locks that were queued ahead of us. */
-	if (count == RWSEM_WAITING_BIAS)
-		sem = __rwsem_do_wake(sem, RWSEM_WAKE_NO_ACTIVE);
-	else if (count > RWSEM_WAITING_BIAS &&
-		 adjustment == -RWSEM_ACTIVE_WRITE_BIAS)
-		sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
-
-	spin_unlock_irq(&sem->wait_lock);
-
-	/* wait to be given the lock */
-	for (;;) {
-		if (!waiter.task)
-			break;
-		schedule();
-		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
-	}
-
-	tsk->state = TASK_RUNNING;
-
-	return sem;
-}
-
-/*
- * wait for the read lock to be granted
- */
-asmregparm struct rw_semaphore __sched *
-rwsem_down_read_failed(struct rw_semaphore *sem)
-{
-	return rwsem_down_failed_common(sem, RWSEM_WAITING_FOR_READ,
-					-RWSEM_ACTIVE_READ_BIAS);
-}
-
-/*
- * wait for the write lock to be granted
- */
-asmregparm struct rw_semaphore __sched *
-rwsem_down_write_failed(struct rw_semaphore *sem)
-{
-	return rwsem_down_failed_common(sem, RWSEM_WAITING_FOR_WRITE,
-					-RWSEM_ACTIVE_WRITE_BIAS);
-}
-
-/*
- * handle waking up a waiter on the semaphore
- * - up_read/up_write has decremented the active part of count if we come here
- */
-asmregparm struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&sem->wait_lock, flags);
-
-	/* do nothing if list empty */
-	if (!list_empty(&sem->wait_list))
-		sem = __rwsem_do_wake(sem, RWSEM_WAKE_ANY);
-
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
-
-	return sem;
-}
-
-/*
- * downgrade a write lock into a read lock
- * - caller incremented waiting part of count and discovered it still negative
- * - just wake up any readers at the front of the queue
- */
-asmregparm struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&sem->wait_lock, flags);
-
-	/* do nothing if list empty */
-	if (!list_empty(&sem->wait_list))
-		sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED);
-
-	spin_unlock_irqrestore(&sem->wait_lock, flags);
-
-	return sem;
-}
-
-EXPORT_SYMBOL(rwsem_down_read_failed);
-EXPORT_SYMBOL(rwsem_down_write_failed);
-EXPORT_SYMBOL(rwsem_wake);
-EXPORT_SYMBOL(rwsem_downgrade_wake);