249 lines
7 KiB
C
249 lines
7 KiB
C
/**************************************************************************
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*
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* Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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* USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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/*
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* Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
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*/
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/** @file ttm_lock.h
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* This file implements a simple replacement for the buffer manager use
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* of the DRM heavyweight hardware lock.
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* The lock is a read-write lock. Taking it in read mode and write mode
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* is relatively fast, and intended for in-kernel use only.
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*
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* The vt mode is used only when there is a need to block all
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* user-space processes from validating buffers.
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* It's allowed to leave kernel space with the vt lock held.
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* If a user-space process dies while having the vt-lock,
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* it will be released during the file descriptor release. The vt lock
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* excludes write lock and read lock.
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*
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* The suspend mode is used to lock out all TTM users when preparing for
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* and executing suspend operations.
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*
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*/
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#ifndef _TTM_LOCK_H_
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#define _TTM_LOCK_H_
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#include <linux/wait.h>
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#include <linux/atomic.h>
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#include "ttm_object.h"
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/**
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* struct ttm_lock
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*
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* @base: ttm base object used solely to release the lock if the client
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* holding the lock dies.
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* @queue: Queue for processes waiting for lock change-of-status.
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* @lock: Spinlock protecting some lock members.
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* @rw: Read-write lock counter. Protected by @lock.
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* @flags: Lock state. Protected by @lock.
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* @kill_takers: Boolean whether to kill takers of the lock.
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* @signal: Signal to send when kill_takers is true.
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*/
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struct ttm_lock {
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struct ttm_base_object base;
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wait_queue_head_t queue;
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spinlock_t lock;
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int32_t rw;
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uint32_t flags;
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bool kill_takers;
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int signal;
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struct ttm_object_file *vt_holder;
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};
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/**
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* ttm_lock_init
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*
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* @lock: Pointer to a struct ttm_lock
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* Initializes the lock.
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*/
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extern void ttm_lock_init(struct ttm_lock *lock);
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/**
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* ttm_read_unlock
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*
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* @lock: Pointer to a struct ttm_lock
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*
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* Releases a read lock.
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*/
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extern void ttm_read_unlock(struct ttm_lock *lock);
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/**
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* ttm_read_lock
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*
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* @lock: Pointer to a struct ttm_lock
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* @interruptible: Interruptible sleeping while waiting for a lock.
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*
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* Takes the lock in read mode.
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* Returns:
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* -ERESTARTSYS If interrupted by a signal and interruptible is true.
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*/
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extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible);
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/**
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* ttm_read_trylock
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*
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* @lock: Pointer to a struct ttm_lock
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* @interruptible: Interruptible sleeping while waiting for a lock.
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*
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* Tries to take the lock in read mode. If the lock is already held
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* in write mode, the function will return -EBUSY. If the lock is held
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* in vt or suspend mode, the function will sleep until these modes
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* are unlocked.
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*
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* Returns:
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* -EBUSY The lock was already held in write mode.
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* -ERESTARTSYS If interrupted by a signal and interruptible is true.
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*/
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extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible);
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/**
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* ttm_write_unlock
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*
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* @lock: Pointer to a struct ttm_lock
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*
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* Releases a write lock.
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*/
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extern void ttm_write_unlock(struct ttm_lock *lock);
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/**
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* ttm_write_lock
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*
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* @lock: Pointer to a struct ttm_lock
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* @interruptible: Interruptible sleeping while waiting for a lock.
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*
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* Takes the lock in write mode.
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* Returns:
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* -ERESTARTSYS If interrupted by a signal and interruptible is true.
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*/
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extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible);
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/**
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* ttm_lock_downgrade
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*
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* @lock: Pointer to a struct ttm_lock
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*
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* Downgrades a write lock to a read lock.
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*/
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extern void ttm_lock_downgrade(struct ttm_lock *lock);
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/**
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* ttm_suspend_lock
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*
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* @lock: Pointer to a struct ttm_lock
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*
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* Takes the lock in suspend mode. Excludes read and write mode.
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*/
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extern void ttm_suspend_lock(struct ttm_lock *lock);
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/**
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* ttm_suspend_unlock
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*
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* @lock: Pointer to a struct ttm_lock
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*
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* Releases a suspend lock
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*/
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extern void ttm_suspend_unlock(struct ttm_lock *lock);
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/**
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* ttm_vt_lock
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*
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* @lock: Pointer to a struct ttm_lock
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* @interruptible: Interruptible sleeping while waiting for a lock.
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* @tfile: Pointer to a struct ttm_object_file to register the lock with.
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*
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* Takes the lock in vt mode.
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* Returns:
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* -ERESTARTSYS If interrupted by a signal and interruptible is true.
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* -ENOMEM: Out of memory when locking.
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*/
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extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible,
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struct ttm_object_file *tfile);
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/**
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* ttm_vt_unlock
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*
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* @lock: Pointer to a struct ttm_lock
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*
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* Releases a vt lock.
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* Returns:
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* -EINVAL If the lock was not held.
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*/
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extern int ttm_vt_unlock(struct ttm_lock *lock);
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/**
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* ttm_write_unlock
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*
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* @lock: Pointer to a struct ttm_lock
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*
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* Releases a write lock.
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*/
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extern void ttm_write_unlock(struct ttm_lock *lock);
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/**
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* ttm_write_lock
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*
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* @lock: Pointer to a struct ttm_lock
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* @interruptible: Interruptible sleeping while waiting for a lock.
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*
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* Takes the lock in write mode.
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* Returns:
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* -ERESTARTSYS If interrupted by a signal and interruptible is true.
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*/
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extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible);
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/**
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* ttm_lock_set_kill
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*
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* @lock: Pointer to a struct ttm_lock
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* @val: Boolean whether to kill processes taking the lock.
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* @signal: Signal to send to the process taking the lock.
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*
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* The kill-when-taking-lock functionality is used to kill processes that keep
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* on using the TTM functionality when its resources has been taken down, for
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* example when the X server exits. A typical sequence would look like this:
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* - X server takes lock in write mode.
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* - ttm_lock_set_kill() is called with @val set to true.
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* - As part of X server exit, TTM resources are taken down.
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* - X server releases the lock on file release.
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* - Another dri client wants to render, takes the lock and is killed.
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*
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*/
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static inline void ttm_lock_set_kill(struct ttm_lock *lock, bool val,
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int signal)
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{
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lock->kill_takers = val;
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if (val)
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lock->signal = signal;
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}
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#endif
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