diff options
Diffstat (limited to 'drivers/gpu/drm/drm_lock.c')
| -rw-r--r-- | drivers/gpu/drm/drm_lock.c | 391 |
1 files changed, 391 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_lock.c b/drivers/gpu/drm/drm_lock.c new file mode 100644 index 00000000000..0998723cde7 --- /dev/null +++ b/drivers/gpu/drm/drm_lock.c @@ -0,0 +1,391 @@ +/** + * \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 "drmP.h" + +static int drm_notifier(void *priv); + +/** + * 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; + 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), + dev->lock.hw_lock->lock, lock->flags); + + if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE)) + if (lock->context < 0) + return -EINVAL; + + add_wait_queue(&dev->lock.lock_queue, &entry); + spin_lock_bh(&dev->lock.spinlock); + dev->lock.user_waiters++; + spin_unlock_bh(&dev->lock.spinlock); + for (;;) { + __set_current_state(TASK_INTERRUPTIBLE); + if (!dev->lock.hw_lock) { + /* Device has been unregistered */ + ret = -EINTR; + break; + } + if (drm_lock_take(&dev->lock, lock->context)) { + dev->lock.file_priv = file_priv; + dev->lock.lock_time = jiffies; + atomic_inc(&dev->counts[_DRM_STAT_LOCKS]); + break; /* Got lock */ + } + + /* Contention */ + schedule(); + if (signal_pending(current)) { + ret = -ERESTARTSYS; + break; + } + } + spin_lock_bh(&dev->lock.spinlock); + dev->lock.user_waiters--; + spin_unlock_bh(&dev->lock.spinlock); + __set_current_state(TASK_RUNNING); + remove_wait_queue(&dev->lock.lock_queue, &entry); + + DRM_DEBUG("%d %s\n", lock->context, + ret ? "interrupted" : "has lock"); + if (ret) return ret; + + 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 = dev->lock.hw_lock; + block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask); + + if (dev->driver->dma_ready && (lock->flags & _DRM_LOCK_READY)) + dev->driver->dma_ready(dev); + + 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; + } + } + + if (dev->driver->kernel_context_switch && + dev->last_context != lock->context) { + dev->driver->kernel_context_switch(dev, dev->last_context, + lock->context); + } + + 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; + unsigned long irqflags; + + if (lock->context == DRM_KERNEL_CONTEXT) { + DRM_ERROR("Process %d using kernel context %d\n", + task_pid_nr(current), lock->context); + return -EINVAL; + } + + spin_lock_irqsave(&dev->tasklet_lock, irqflags); + + if (dev->locked_tasklet_func) { + dev->locked_tasklet_func(dev); + + dev->locked_tasklet_func = NULL; + } + + spin_unlock_irqrestore(&dev->tasklet_lock, irqflags); + + 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. + */ + if (dev->driver->kernel_context_switch_unlock) + dev->driver->kernel_context_switch_unlock(dev); + else { + if (drm_lock_free(&dev->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. + */ +int 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 = 0; + + 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) +{ + return (file_priv->lock_count && dev->lock.hw_lock && + _DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) && + dev->lock.file_priv == file_priv); +} + +EXPORT_SYMBOL(drm_i_have_hw_lock); |