/* * Copyright (c) 2006, 2012, Oracle and/or its affiliates. All rights reserved. */ /* * Copyright (c) 2012 Intel Corporation. All rights reserved. */ /** * \file drm_lock.c * IOCTLs for locking * * \author Rickard E. (Rik) Faith * \author Gareth Hughes */ /* * 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 "drmP.h" /** * 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. */ /* LINTED */ int drm_lock(DRM_IOCTL_ARGS) { struct drm_lock *lock = data; struct drm_master *master = file->master; int ret = 0; ++file->lock_count; if (lock->context == DRM_KERNEL_CONTEXT) { DRM_ERROR("Process %d using kernel context %d\n", DRM_CURRENTPID, lock->context); return -EINVAL; } if (master->lock.hw_lock == NULL) return -EINVAL; DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n", lock->context, DRM_CURRENTPID, master->lock.hw_lock->lock, lock->flags); if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE)) if (lock->context < 0) return -EINVAL; mutex_enter(&master->lock.lock_mutex); master->lock.user_waiters++; for (;;) { if (drm_lock_take(&master->lock, lock->context)) { master->lock.file_priv = file; master->lock.lock_time = ddi_get_lbolt(); atomic_inc(&dev->counts[_DRM_STAT_LOCKS]); break; /* Got lock */ } ret = cv_wait_sig(&master->lock.lock_cv, &master->lock.lock_mutex); if (ret == 0) { ret = -EINTR; break; } } master->lock.user_waiters--; mutex_exit(&master->lock.lock_mutex); DRM_DEBUG("%d %s\n", lock->context, ret ? "interrupted" : "has lock"); if (ret) return ret; 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. */ /* LINTED */ int drm_unlock(DRM_IOCTL_ARGS) { struct drm_lock *lock = data; struct drm_master *master = file->master; if (lock->context == DRM_KERNEL_CONTEXT) { DRM_ERROR("Process %d using kernel context %d\n", DRM_CURRENTPID, lock->context); return -EINVAL; } atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]); /* kernel_context_switch isn't used by any of the x86 drm * modules but is required by the Sparc driver. */ /* LINTED */ if (drm_lock_free(&master->lock, lock->context)) { /* FIXME: Should really bail out here. */ } 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. */ int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context) { unsigned int old, new; volatile unsigned int *lock = &lock_data->hw_lock->lock; 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); } } while (!atomic_cmpset_int(lock, old, new)); 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; volatile unsigned int *lock = &lock_data->hw_lock->lock; lock_data->file_priv = NULL; do { old = *lock; new = context | _DRM_LOCK_HELD; } while (!atomic_cmpset_int(lock, old, new)); 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; volatile unsigned int *lock = &lock_data->hw_lock->lock; mutex_enter(&lock_data->lock_mutex); if (lock_data->kernel_waiters != 0) { (void) drm_lock_transfer(lock_data, 0); lock_data->idle_has_lock = 1; mutex_exit(&lock_data->lock_mutex); return 1; } do { old = *lock; new = _DRM_LOCKING_CONTEXT(old); } while (!atomic_cmpset_int(lock, old, new)); 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)); mutex_exit(&lock_data->lock_mutex); return 1; } cv_broadcast(&lock_data->lock_cv); mutex_exit(&lock_data->lock_mutex); 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 = 0; mutex_enter(&lock_data->lock_mutex); lock_data->kernel_waiters++; if (!lock_data->idle_has_lock) { ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT); if (ret == 1) lock_data->idle_has_lock = 1; } mutex_exit(&(lock_data->lock_mutex)); } void drm_idlelock_release(struct drm_lock_data *lock_data) { unsigned int old; volatile unsigned int *lock = &lock_data->hw_lock->lock; mutex_enter(&lock_data->lock_mutex); if (--lock_data->kernel_waiters == 0) { if (lock_data->idle_has_lock) { do { old = *lock; } while (!atomic_cmpset_int(lock, old, DRM_KERNEL_CONTEXT)); cv_broadcast(&lock_data->lock_cv); lock_data->idle_has_lock = 0; } } mutex_exit(&lock_data->lock_mutex); } /* LINTED */ 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); }