/************************************************************************** * * 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 <ttm/ttm_object.h> #include <linux/wait.h> #include <linux/atomic.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