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/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/**************************************************************************
*
* Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/*
* Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
*/
#include <linux/atomic.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/sched/signal.h>
#include "ttm_lock.h"
#include "ttm_object.h"
#define TTM_WRITE_LOCK_PENDING (1 << 0)
#define TTM_VT_LOCK_PENDING (1 << 1)
#define TTM_SUSPEND_LOCK_PENDING (1 << 2)
#define TTM_VT_LOCK (1 << 3)
#define TTM_SUSPEND_LOCK (1 << 4)
void ttm_lock_init(struct ttm_lock *lock)
{
spin_lock_init(&lock->lock);
init_waitqueue_head(&lock->queue);
lock->rw = 0;
lock->flags = 0;
}
void ttm_read_unlock(struct ttm_lock *lock)
{
spin_lock(&lock->lock);
if (--lock->rw == 0)
wake_up_all(&lock->queue);
spin_unlock(&lock->lock);
}
static bool __ttm_read_lock(struct ttm_lock *lock)
{
bool locked = false;
spin_lock(&lock->lock);
if (lock->rw >= 0 && lock->flags == 0) {
++lock->rw;
locked = true;
}
spin_unlock(&lock->lock);
return locked;
}
int ttm_read_lock(struct ttm_lock *lock, bool interruptible)
{
int ret = 0;
if (interruptible)
ret = wait_event_interruptible(lock->queue,
__ttm_read_lock(lock));
else
wait_event(lock->queue, __ttm_read_lock(lock));
return ret;
}
static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
{
bool block = true;
*locked = false;
spin_lock(&lock->lock);
if (lock->rw >= 0 && lock->flags == 0) {
++lock->rw;
block = false;
*locked = true;
} else if (lock->flags == 0) {
block = false;
}
spin_unlock(&lock->lock);
return !block;
}
int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
{
int ret = 0;
bool locked;
if (interruptible)
ret = wait_event_interruptible
(lock->queue, __ttm_read_trylock(lock, &locked));
else
wait_event(lock->queue, __ttm_read_trylock(lock, &locked));
if (unlikely(ret != 0)) {
BUG_ON(locked);
return ret;
}
return (locked) ? 0 : -EBUSY;
}
void ttm_write_unlock(struct ttm_lock *lock)
{
spin_lock(&lock->lock);
lock->rw = 0;
wake_up_all(&lock->queue);
spin_unlock(&lock->lock);
}
static bool __ttm_write_lock(struct ttm_lock *lock)
{
bool locked = false;
spin_lock(&lock->lock);
if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
lock->rw = -1;
lock->flags &= ~TTM_WRITE_LOCK_PENDING;
locked = true;
} else {
lock->flags |= TTM_WRITE_LOCK_PENDING;
}
spin_unlock(&lock->lock);
return locked;
}
int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
{
int ret = 0;
if (interruptible) {
ret = wait_event_interruptible(lock->queue,
__ttm_write_lock(lock));
if (unlikely(ret != 0)) {
spin_lock(&lock->lock);
lock->flags &= ~TTM_WRITE_LOCK_PENDING;
wake_up_all(&lock->queue);
spin_unlock(&lock->lock);
}
} else
wait_event(lock->queue, __ttm_write_lock(lock));
return ret;
}
void ttm_suspend_unlock(struct ttm_lock *lock)
{
spin_lock(&lock->lock);
lock->flags &= ~TTM_SUSPEND_LOCK;
wake_up_all(&lock->queue);
spin_unlock(&lock->lock);
}
static bool __ttm_suspend_lock(struct ttm_lock *lock)
{
bool locked = false;
spin_lock(&lock->lock);
if (lock->rw == 0) {
lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
lock->flags |= TTM_SUSPEND_LOCK;
locked = true;
} else {
lock->flags |= TTM_SUSPEND_LOCK_PENDING;
}
spin_unlock(&lock->lock);
return locked;
}
void ttm_suspend_lock(struct ttm_lock *lock)
{
wait_event(lock->queue, __ttm_suspend_lock(lock));
}
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