diff options
Diffstat (limited to 'drivers/staging/psb/ttm/ttm_lock.c')
| -rw-r--r-- | drivers/staging/psb/ttm/ttm_lock.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/drivers/staging/psb/ttm/ttm_lock.c b/drivers/staging/psb/ttm/ttm_lock.c new file mode 100644 index 000000000000..2367c200addb --- /dev/null +++ b/drivers/staging/psb/ttm/ttm_lock.c @@ -0,0 +1,162 @@ +/************************************************************************** + * + * Copyright (c) 2007-2008 Tungsten Graphics, Inc., Cedar Park, TX., USA + * All Rights Reserved. + * Copyright (c) 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 Hellström <thomas-at-tungstengraphics-dot-com> + */ + +#include "ttm_lock.h" +#include <asm/atomic.h> +#include <linux/errno.h> +#include <linux/wait.h> +#include <linux/sched.h> + +void ttm_lock_init(struct ttm_lock *lock) +{ + init_waitqueue_head(&lock->queue); + atomic_set(&lock->write_lock_pending, 0); + atomic_set(&lock->readers, 0); + lock->kill_takers = false; + lock->signal = SIGKILL; +} + +void ttm_read_unlock(struct ttm_lock *lock) +{ + if (atomic_dec_and_test(&lock->readers)) + wake_up_all(&lock->queue); +} + +int ttm_read_lock(struct ttm_lock *lock, bool interruptible) +{ + while (unlikely(atomic_read(&lock->write_lock_pending) != 0)) { + int ret; + + if (!interruptible) { + wait_event(lock->queue, + atomic_read(&lock->write_lock_pending) == 0); + continue; + } + ret = wait_event_interruptible + (lock->queue, atomic_read(&lock->write_lock_pending) == 0); + if (ret) + return -ERESTART; + } + + while (unlikely(!atomic_add_unless(&lock->readers, 1, -1))) { + int ret; + if (!interruptible) { + wait_event(lock->queue, + atomic_read(&lock->readers) != -1); + continue; + } + ret = wait_event_interruptible + (lock->queue, atomic_read(&lock->readers) != -1); + if (ret) + return -ERESTART; + } + + if (unlikely(lock->kill_takers)) { + send_sig(lock->signal, current, 0); + ttm_read_unlock(lock); + return -ERESTART; + } + + return 0; +} + +static int __ttm_write_unlock(struct ttm_lock *lock) +{ + if (unlikely(atomic_cmpxchg(&lock->readers, -1, 0) != -1)) + return -EINVAL; + wake_up_all(&lock->queue); + return 0; +} + +static void ttm_write_lock_remove(struct ttm_base_object **p_base) +{ + struct ttm_base_object *base = *p_base; + struct ttm_lock *lock = container_of(base, struct ttm_lock, base); + int ret; + + *p_base = NULL; + ret = __ttm_write_unlock(lock); + BUG_ON(ret != 0); +} + +int ttm_write_lock(struct ttm_lock *lock, + bool interruptible, + struct ttm_object_file *tfile) +{ + int ret = 0; + + atomic_inc(&lock->write_lock_pending); + + while (unlikely(atomic_cmpxchg(&lock->readers, 0, -1) != 0)) { + if (!interruptible) { + wait_event(lock->queue, + atomic_read(&lock->readers) == 0); + continue; + } + ret = wait_event_interruptible + (lock->queue, atomic_read(&lock->readers) == 0); + + if (ret) { + if (atomic_dec_and_test(&lock->write_lock_pending)) + wake_up_all(&lock->queue); + return -ERESTART; + } + } + + if (atomic_dec_and_test(&lock->write_lock_pending)) + wake_up_all(&lock->queue); + + if (unlikely(lock->kill_takers)) { + send_sig(lock->signal, current, 0); + __ttm_write_unlock(lock); + return -ERESTART; + } + + /* + * Add a base-object, the destructor of which will + * make sure the lock is released if the client dies + * while holding it. + */ + + ret = ttm_base_object_init(tfile, &lock->base, false, + ttm_lock_type, &ttm_write_lock_remove, NULL); + if (ret) + (void)__ttm_write_unlock(lock); + + return ret; +} + +int ttm_write_unlock(struct ttm_lock *lock, struct ttm_object_file *tfile) +{ + return ttm_ref_object_base_unref(tfile, + lock->base.hash.key, TTM_REF_USAGE); +} |