/** * \file drm_lock.c * IOCTLs for locking * * \author Rickard E. (Rik) Faith <faith@valinux.com> * \author Gareth Hughes <gareth@valinux.com> */ /* * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com * * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas. * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California. * 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, sublicense, * 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 NONINFRINGEMENT.  IN NO EVENT SHALL * VA LINUX SYSTEMS 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. */ #include <linux/export.h>#include <drm/drmP.h> static int drm_notifier(void *priv); static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context); /** * Lock ioctl. * * \param inode device inode. * \param file_priv DRM file private. * \param cmd command. * \param arg user argument, pointing to a drm_lock structure. * \return zero on success or negative number on failure. * * Add the current task to the lock wait queue, and attempt to take to lock. */int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv){	DECLARE_WAITQUEUE(entry, current);	struct drm_lock *lock = data;	struct drm_master *master = file_priv->master;	int ret = 0; 	++file_priv->lock_count; 	if (lock->context == DRM_KERNEL_CONTEXT) {		DRM_ERROR("Process %d using kernel context %d\n",			  task_pid_nr(current), lock->context);		return -EINVAL;	} 	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",		  lock->context, task_pid_nr(current),		  master->lock.hw_lock->lock, lock->flags); 	add_wait_queue(&master->lock.lock_queue, &entry);	spin_lock_bh(&master->lock.spinlock);	master->lock.user_waiters++;	spin_unlock_bh(&master->lock.spinlock); 	for (;;) {		__set_current_state(TASK_INTERRUPTIBLE);		if (!master->lock.hw_lock) {			/* Device has been unregistered */			send_sig(SIGTERM, current, 0);			ret = -EINTR;			break;		}		if (drm_lock_take(&master->lock, lock->context)) {			master->lock.file_priv = file_priv;			master->lock.lock_time = jiffies;			break;	/* Got lock */		} 		/* Contention */		mutex_unlock(&drm_global_mutex);		schedule();		mutex_lock(&drm_global_mutex);		if (signal_pending(current)) {			ret = -EINTR;			break;		}	}	spin_lock_bh(&master->lock.spinlock);	master->lock.user_waiters--;	spin_unlock_bh(&master->lock.spinlock);	__set_current_state(TASK_RUNNING);	remove_wait_queue(&master->lock.lock_queue, &entry); 	DRM_DEBUG("%d %s\n", lock->context,		  ret ? "interrupted" : "has lock");	if (ret) return ret; 	/* don't set the block all signals on the master process for now 	 * really probably not the correct answer but lets us debug xkb 	 * xserver for now */	if (!file_priv->is_master) {		sigemptyset(&dev->sigmask);		sigaddset(&dev->sigmask, SIGSTOP);		sigaddset(&dev->sigmask, SIGTSTP);		sigaddset(&dev->sigmask, SIGTTIN);		sigaddset(&dev->sigmask, SIGTTOU);		dev->sigdata.context = lock->context;		dev->sigdata.lock = master->lock.hw_lock;		block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);	} 	if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))	{		if (dev->driver->dma_quiescent(dev)) {			DRM_DEBUG("%d waiting for DMA quiescent\n",				  lock->context);			return -EBUSY;		}	} 	return 0;} /** * Unlock ioctl. * * \param inode device inode. * \param file_priv DRM file private. * \param cmd command. * \param arg user argument, pointing to a drm_lock structure. * \return zero on success or negative number on failure. * * Transfer and free the lock. */int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv){	struct drm_lock *lock = data;	struct drm_master *master = file_priv->master; 	if (lock->context == DRM_KERNEL_CONTEXT) {		DRM_ERROR("Process %d using kernel context %d\n",			  task_pid_nr(current), lock->context);		return -EINVAL;	} 	if (drm_lock_free(&master->lock, lock->context)) {		/* FIXME: Should really bail out here. */	} 	unblock_all_signals();	return 0;} /** * Take the heavyweight lock. * * \param lock lock pointer. * \param context locking context. * \return one if the lock is held, or zero otherwise. * * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction. */staticint drm_lock_take(struct drm_lock_data *lock_data,		  unsigned int context){	unsigned int old, new, prev;	volatile unsigned int *lock = &lock_data->hw_lock->lock; 	spin_lock_bh(&lock_data->spinlock);	do {		old = *lock;		if (old & _DRM_LOCK_HELD)			new = old | _DRM_LOCK_CONT;		else {			new = context | _DRM_LOCK_HELD |				((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?				 _DRM_LOCK_CONT : 0);		}		prev = cmpxchg(lock, old, new);	} while (prev != old);	spin_unlock_bh(&lock_data->spinlock); 	if (_DRM_LOCKING_CONTEXT(old) == context) {		if (old & _DRM_LOCK_HELD) {			if (context != DRM_KERNEL_CONTEXT) {				DRM_ERROR("%d holds heavyweight lock\n",					  context);			}			return 0;		}	} 	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {		/* Have lock */		return 1;	}	return 0;} /** * This takes a lock forcibly and hands it to context.	Should ONLY be used * inside *_unlock to give lock to kernel before calling *_dma_schedule. * * \param dev DRM device. * \param lock lock pointer. * \param context locking context. * \return always one. * * Resets the lock file pointer. * Marks the lock as held by the given context, via the \p cmpxchg instruction. */static int drm_lock_transfer(struct drm_lock_data *lock_data,			     unsigned int context){	unsigned int old, new, prev;	volatile unsigned int *lock = &lock_data->hw_lock->lock; 	lock_data->file_priv = NULL;	do {		old = *lock;		new = context | _DRM_LOCK_HELD;		prev = cmpxchg(lock, old, new);	} while (prev != old);	return 1;} /** * Free lock. * * \param dev DRM device. * \param lock lock. * \param context context. * * Resets the lock file pointer. * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task * waiting on the lock queue. */int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context){	unsigned int old, new, prev;	volatile unsigned int *lock = &lock_data->hw_lock->lock; 	spin_lock_bh(&lock_data->spinlock);	if (lock_data->kernel_waiters != 0) {		drm_lock_transfer(lock_data, 0);		lock_data->idle_has_lock = 1;		spin_unlock_bh(&lock_data->spinlock);		return 1;	}	spin_unlock_bh(&lock_data->spinlock); 	do {		old = *lock;		new = _DRM_LOCKING_CONTEXT(old);		prev = cmpxchg(lock, old, new);	} while (prev != old); 	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {		DRM_ERROR("%d freed heavyweight lock held by %d\n",			  context, _DRM_LOCKING_CONTEXT(old));		return 1;	}	wake_up_interruptible(&lock_data->lock_queue);	return 0;} /** * If we get here, it means that the process has called DRM_IOCTL_LOCK * without calling DRM_IOCTL_UNLOCK. * * If the lock is not held, then let the signal proceed as usual.  If the lock * is held, then set the contended flag and keep the signal blocked. * * \param priv pointer to a drm_sigdata structure. * \return one if the signal should be delivered normally, or zero if the * signal should be blocked. */static int drm_notifier(void *priv){	struct drm_sigdata *s = (struct drm_sigdata *) priv;	unsigned int old, new, prev; 	/* Allow signal delivery if lock isn't held */	if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)	    || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)		return 1; 	/* Otherwise, set flag to force call to	   drmUnlock */	do {		old = s->lock->lock;		new = old | _DRM_LOCK_CONT;		prev = cmpxchg(&s->lock->lock, old, new);	} while (prev != old);	return 0;} /** * This function returns immediately and takes the hw lock * with the kernel context if it is free, otherwise it gets the highest priority when and if * it is eventually released. * * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause * a deadlock, which is why the "idlelock" was invented). * * This should be sufficient to wait for GPU idle without * having to worry about starvation. */ void drm_idlelock_take(struct drm_lock_data *lock_data){	int ret; 	spin_lock_bh(&lock_data->spinlock);	lock_data->kernel_waiters++;	if (!lock_data->idle_has_lock) { 		spin_unlock_bh(&lock_data->spinlock);		ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);		spin_lock_bh(&lock_data->spinlock); 		if (ret == 1)			lock_data->idle_has_lock = 1;	}	spin_unlock_bh(&lock_data->spinlock);}EXPORT_SYMBOL(drm_idlelock_take); void drm_idlelock_release(struct drm_lock_data *lock_data){	unsigned int old, prev;	volatile unsigned int *lock = &lock_data->hw_lock->lock; 	spin_lock_bh(&lock_data->spinlock);	if (--lock_data->kernel_waiters == 0) {		if (lock_data->idle_has_lock) {			do {				old = *lock;				prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);			} while (prev != old);			wake_up_interruptible(&lock_data->lock_queue);			lock_data->idle_has_lock = 0;		}	}	spin_unlock_bh(&lock_data->spinlock);}EXPORT_SYMBOL(drm_idlelock_release); int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv){	struct drm_master *master = file_priv->master;	return (file_priv->lock_count && master->lock.hw_lock &&		_DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&		master->lock.file_priv == file_priv);}