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| -rw-r--r-- | include/drm/ttm/ttm_lock.h | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/include/drm/ttm/ttm_lock.h b/include/drm/ttm/ttm_lock.h new file mode 100644 index 000000000..0c3af9836 --- /dev/null +++ b/include/drm/ttm/ttm_lock.h @@ -0,0 +1,248 @@ +/************************************************************************** + * + * 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> + */ + +/** @file ttm_lock.h + * This file implements a simple replacement for the buffer manager use + * of the DRM heavyweight hardware lock. + * The lock is a read-write lock. Taking it in read mode and write mode + * is relatively fast, and intended for in-kernel use only. + * + * The vt mode is used only when there is a need to block all + * user-space processes from validating buffers. + * It's allowed to leave kernel space with the vt lock held. + * If a user-space process dies while having the vt-lock, + * it will be released during the file descriptor release. The vt lock + * excludes write lock and read lock. + * + * The suspend mode is used to lock out all TTM users when preparing for + * and executing suspend operations. + * + */ + +#ifndef _TTM_LOCK_H_ +#define _TTM_LOCK_H_ + +#include <linux/wait.h> +#include <linux/atomic.h> + +#include "ttm_object.h" + +/** + * struct ttm_lock + * + * @base: ttm base object used solely to release the lock if the client + * holding the lock dies. + * @queue: Queue for processes waiting for lock change-of-status. + * @lock: Spinlock protecting some lock members. + * @rw: Read-write lock counter. Protected by @lock. + * @flags: Lock state. Protected by @lock. + * @kill_takers: Boolean whether to kill takers of the lock. + * @signal: Signal to send when kill_takers is true. + */ + +struct ttm_lock { + struct ttm_base_object base; + wait_queue_head_t queue; + spinlock_t lock; + int32_t rw; + uint32_t flags; + bool kill_takers; + int signal; + struct ttm_object_file *vt_holder; +}; + + +/** + * ttm_lock_init + * + * @lock: Pointer to a struct ttm_lock + * Initializes the lock. + */ +extern void ttm_lock_init(struct ttm_lock *lock); + +/** + * ttm_read_unlock + * + * @lock: Pointer to a struct ttm_lock + * + * Releases a read lock. + */ +extern void ttm_read_unlock(struct ttm_lock *lock); + +/** + * ttm_read_lock + * + * @lock: Pointer to a struct ttm_lock + * @interruptible: Interruptible sleeping while waiting for a lock. + * + * Takes the lock in read mode. + * Returns: + * -ERESTARTSYS If interrupted by a signal and interruptible is true. + */ +extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible); + +/** + * ttm_read_trylock + * + * @lock: Pointer to a struct ttm_lock + * @interruptible: Interruptible sleeping while waiting for a lock. + * + * Tries to take the lock in read mode. If the lock is already held + * in write mode, the function will return -EBUSY. If the lock is held + * in vt or suspend mode, the function will sleep until these modes + * are unlocked. + * + * Returns: + * -EBUSY The lock was already held in write mode. + * -ERESTARTSYS If interrupted by a signal and interruptible is true. + */ +extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible); + +/** + * ttm_write_unlock + * + * @lock: Pointer to a struct ttm_lock + * + * Releases a write lock. + */ +extern void ttm_write_unlock(struct ttm_lock *lock); + +/** + * ttm_write_lock + * + * @lock: Pointer to a struct ttm_lock + * @interruptible: Interruptible sleeping while waiting for a lock. + * + * Takes the lock in write mode. + * Returns: + * -ERESTARTSYS If interrupted by a signal and interruptible is true. + */ +extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible); + +/** + * ttm_lock_downgrade + * + * @lock: Pointer to a struct ttm_lock + * + * Downgrades a write lock to a read lock. + */ +extern void ttm_lock_downgrade(struct ttm_lock *lock); + +/** + * ttm_suspend_lock + * + * @lock: Pointer to a struct ttm_lock + * + * Takes the lock in suspend mode. Excludes read and write mode. + */ +extern void ttm_suspend_lock(struct ttm_lock *lock); + +/** + * ttm_suspend_unlock + * + * @lock: Pointer to a struct ttm_lock + * + * Releases a suspend lock + */ +extern void ttm_suspend_unlock(struct ttm_lock *lock); + +/** + * ttm_vt_lock + * + * @lock: Pointer to a struct ttm_lock + * @interruptible: Interruptible sleeping while waiting for a lock. + * @tfile: Pointer to a struct ttm_object_file to register the lock with. + * + * Takes the lock in vt mode. + * Returns: + * -ERESTARTSYS If interrupted by a signal and interruptible is true. + * -ENOMEM: Out of memory when locking. + */ +extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible, + struct ttm_object_file *tfile); + +/** + * ttm_vt_unlock + * + * @lock: Pointer to a struct ttm_lock + * + * Releases a vt lock. + * Returns: + * -EINVAL If the lock was not held. + */ +extern int ttm_vt_unlock(struct ttm_lock *lock); + +/** + * ttm_write_unlock + * + * @lock: Pointer to a struct ttm_lock + * + * Releases a write lock. + */ +extern void ttm_write_unlock(struct ttm_lock *lock); + +/** + * ttm_write_lock + * + * @lock: Pointer to a struct ttm_lock + * @interruptible: Interruptible sleeping while waiting for a lock. + * + * Takes the lock in write mode. + * Returns: + * -ERESTARTSYS If interrupted by a signal and interruptible is true. + */ +extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible); + +/** + * ttm_lock_set_kill + * + * @lock: Pointer to a struct ttm_lock + * @val: Boolean whether to kill processes taking the lock. + * @signal: Signal to send to the process taking the lock. + * + * The kill-when-taking-lock functionality is used to kill processes that keep + * on using the TTM functionality when its resources has been taken down, for + * example when the X server exits. A typical sequence would look like this: + * - X server takes lock in write mode. + * - ttm_lock_set_kill() is called with @val set to true. + * - As part of X server exit, TTM resources are taken down. + * - X server releases the lock on file release. + * - Another dri client wants to render, takes the lock and is killed. + * + */ +static inline void ttm_lock_set_kill(struct ttm_lock *lock, bool val, + int signal) +{ + lock->kill_takers = val; + if (val) + lock->signal = signal; +} + +#endif |