/************************************************************************** * * 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 "ttm/ttm_lock.h" #include "ttm/ttm_module.h" #include <asm/atomic.h> #include <linux/errno.h> #include <linux/wait.h> #include <linux/sched.h> #include <linux/module.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; lock->kill_takers = false; lock->signal = SIGKILL; } EXPORT_SYMBOL(ttm_lock_init); 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); } EXPORT_SYMBOL(ttm_read_unlock); static bool __ttm_read_lock(struct ttm_lock *lock) { bool locked = false; spin_lock(&lock->lock); if (unlikely(lock->kill_takers)) { send_sig(lock->signal, current, 0); spin_unlock(&lock->lock); return false; } 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; } EXPORT_SYMBOL(ttm_read_lock); static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked) { bool block = true; *locked = false; spin_lock(&lock->lock); if (unlikely(lock->kill_takers)) { send_sig(lock->signal, current, 0); spin_unlock(&lock->lock); return false; } 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); } EXPORT_SYMBOL(ttm_write_unlock); static bool __ttm_write_lock(struct ttm_lock *lock) { bool locked = false; spin_lock(&lock->lock); if (unlikely(lock->kill_takers)) { send_sig(lock->signal, current, 0); spin_unlock(&lock->lock); return false; } 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_read_lock(lock)); return ret; } EXPORT_SYMBOL(ttm_write_lock); void ttm_write_lock_downgrade(struct ttm_lock *lock) { spin_lock(&lock->lock); lock->rw = 1; wake_up_all(&lock->queue); spin_unlock(&lock->lock); } static int __ttm_vt_unlock(struct ttm_lock *lock) { int ret = 0; spin_lock(&lock->lock); if (unlikely(!(lock->flags & TTM_VT_LOCK))) ret = -EINVAL; lock->flags &= ~TTM_VT_LOCK; wake_up_all(&lock->queue); spin_unlock(&lock->lock); printk(KERN_INFO TTM_PFX "vt unlock.\n"); return ret; } static void ttm_vt_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_vt_unlock(lock); BUG_ON(ret != 0); } static bool __ttm_vt_lock(struct ttm_lock *lock) { bool locked = false; spin_lock(&lock->lock); if (lock->rw == 0) { lock->flags &= ~TTM_VT_LOCK_PENDING; lock->flags |= TTM_VT_LOCK; locked = true; } else { lock->flags |= TTM_VT_LOCK_PENDING; } spin_unlock(&lock->lock); return locked; } int ttm_vt_lock(struct ttm_lock *lock, bool interruptible, struct ttm_object_file *tfile) { int ret = 0; if (interruptible) { ret = wait_event_interruptible(lock->queue, __ttm_vt_lock(lock)); if (unlikely(ret != 0)) { spin_lock(&lock->lock); lock->flags &= ~TTM_VT_LOCK_PENDING; wake_up_all(&lock->queue); spin_unlock(&lock->lock); return ret; } } else wait_event(lock->queue, __ttm_vt_lock(lock)); /* * 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_vt_lock_remove, NULL); if (ret) (void)__ttm_vt_unlock(lock); else { lock->vt_holder = tfile; printk(KERN_INFO TTM_PFX "vt lock.\n"); } return ret; } EXPORT_SYMBOL(ttm_vt_lock); int ttm_vt_unlock(struct ttm_lock *lock) { return ttm_ref_object_base_unref(lock->vt_holder, lock->base.hash.key, TTM_REF_USAGE); } EXPORT_SYMBOL(ttm_vt_unlock); 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); } EXPORT_SYMBOL(ttm_suspend_unlock); 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)); } EXPORT_SYMBOL(ttm_suspend_lock);