304 lines
8.5 KiB
C
304 lines
8.5 KiB
C
/**
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* \file drm_lock.h
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* IOCTLs for locking
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*
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* \author Rickard E. (Rik) Faith <faith@valinux.com>
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* \author Gareth Hughes <gareth@valinux.com>
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*/
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/*
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* Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
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*
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* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
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* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
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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 "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* 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 NONINFRINGEMENT. IN NO EVENT SHALL
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* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "drmP.h"
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/**
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* Lock ioctl.
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*
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* \param inode device inode.
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* \param filp file pointer.
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* \param cmd command.
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* \param arg user argument, pointing to a drm_lock structure.
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* \return zero on success or negative number on failure.
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*
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* Add the current task to the lock wait queue, and attempt to take to lock.
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*/
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int drm_lock( struct inode *inode, struct file *filp,
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unsigned int cmd, unsigned long arg )
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{
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drm_file_t *priv = filp->private_data;
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drm_device_t *dev = priv->head->dev;
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DECLARE_WAITQUEUE( entry, current );
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drm_lock_t lock;
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int ret = 0;
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++priv->lock_count;
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if ( copy_from_user( &lock, (drm_lock_t __user *)arg, sizeof(lock) ) )
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return -EFAULT;
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if ( lock.context == DRM_KERNEL_CONTEXT ) {
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DRM_ERROR( "Process %d using kernel context %d\n",
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current->pid, lock.context );
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return -EINVAL;
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}
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DRM_DEBUG( "%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
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lock.context, current->pid,
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dev->lock.hw_lock->lock, lock.flags );
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if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
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if ( lock.context < 0 )
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return -EINVAL;
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add_wait_queue( &dev->lock.lock_queue, &entry );
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for (;;) {
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__set_current_state(TASK_INTERRUPTIBLE);
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if ( !dev->lock.hw_lock ) {
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/* Device has been unregistered */
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ret = -EINTR;
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break;
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}
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if ( drm_lock_take( &dev->lock.hw_lock->lock,
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lock.context ) ) {
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dev->lock.filp = filp;
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dev->lock.lock_time = jiffies;
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atomic_inc( &dev->counts[_DRM_STAT_LOCKS] );
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break; /* Got lock */
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}
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/* Contention */
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schedule();
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if ( signal_pending( current ) ) {
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ret = -ERESTARTSYS;
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break;
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}
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}
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__set_current_state(TASK_RUNNING);
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remove_wait_queue( &dev->lock.lock_queue, &entry );
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sigemptyset( &dev->sigmask );
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sigaddset( &dev->sigmask, SIGSTOP );
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sigaddset( &dev->sigmask, SIGTSTP );
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sigaddset( &dev->sigmask, SIGTTIN );
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sigaddset( &dev->sigmask, SIGTTOU );
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dev->sigdata.context = lock.context;
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dev->sigdata.lock = dev->lock.hw_lock;
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block_all_signals( drm_notifier,
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&dev->sigdata, &dev->sigmask );
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if (dev->driver->dma_ready && (lock.flags & _DRM_LOCK_READY))
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dev->driver->dma_ready(dev);
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if ( dev->driver->dma_quiescent && (lock.flags & _DRM_LOCK_QUIESCENT ))
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return dev->driver->dma_quiescent(dev);
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/* dev->driver->kernel_context_switch isn't used by any of the x86
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* drivers but is used by the Sparc driver.
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*/
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if (dev->driver->kernel_context_switch &&
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dev->last_context != lock.context) {
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dev->driver->kernel_context_switch(dev, dev->last_context,
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lock.context);
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}
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DRM_DEBUG( "%d %s\n", lock.context, ret ? "interrupted" : "has lock" );
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return ret;
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}
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/**
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* Unlock ioctl.
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*
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* \param inode device inode.
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* \param filp file pointer.
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* \param cmd command.
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* \param arg user argument, pointing to a drm_lock structure.
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* \return zero on success or negative number on failure.
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*
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* Transfer and free the lock.
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*/
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int drm_unlock( struct inode *inode, struct file *filp,
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unsigned int cmd, unsigned long arg )
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{
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drm_file_t *priv = filp->private_data;
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drm_device_t *dev = priv->head->dev;
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drm_lock_t lock;
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if ( copy_from_user( &lock, (drm_lock_t __user *)arg, sizeof(lock) ) )
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return -EFAULT;
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if ( lock.context == DRM_KERNEL_CONTEXT ) {
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DRM_ERROR( "Process %d using kernel context %d\n",
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current->pid, lock.context );
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return -EINVAL;
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}
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atomic_inc( &dev->counts[_DRM_STAT_UNLOCKS] );
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/* kernel_context_switch isn't used by any of the x86 drm
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* modules but is required by the Sparc driver.
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*/
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if (dev->driver->kernel_context_switch_unlock)
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dev->driver->kernel_context_switch_unlock(dev, &lock);
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else {
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drm_lock_transfer( dev, &dev->lock.hw_lock->lock,
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DRM_KERNEL_CONTEXT );
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if ( drm_lock_free( dev, &dev->lock.hw_lock->lock,
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DRM_KERNEL_CONTEXT ) ) {
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DRM_ERROR( "\n" );
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}
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}
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unblock_all_signals();
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return 0;
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}
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/**
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* Take the heavyweight lock.
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*
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* \param lock lock pointer.
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* \param context locking context.
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* \return one if the lock is held, or zero otherwise.
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*
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* Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
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*/
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int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
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{
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unsigned int old, new, prev;
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do {
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old = *lock;
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if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
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else new = context | _DRM_LOCK_HELD;
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prev = cmpxchg(lock, old, new);
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} while (prev != old);
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if (_DRM_LOCKING_CONTEXT(old) == context) {
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if (old & _DRM_LOCK_HELD) {
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if (context != DRM_KERNEL_CONTEXT) {
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DRM_ERROR("%d holds heavyweight lock\n",
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context);
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}
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return 0;
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}
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}
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if (new == (context | _DRM_LOCK_HELD)) {
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/* Have lock */
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return 1;
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}
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return 0;
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}
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/**
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* This takes a lock forcibly and hands it to context. Should ONLY be used
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* inside *_unlock to give lock to kernel before calling *_dma_schedule.
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*
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* \param dev DRM device.
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* \param lock lock pointer.
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* \param context locking context.
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* \return always one.
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*
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* Resets the lock file pointer.
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* Marks the lock as held by the given context, via the \p cmpxchg instruction.
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*/
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int drm_lock_transfer(drm_device_t *dev,
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__volatile__ unsigned int *lock, unsigned int context)
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{
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unsigned int old, new, prev;
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dev->lock.filp = NULL;
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do {
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old = *lock;
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new = context | _DRM_LOCK_HELD;
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prev = cmpxchg(lock, old, new);
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} while (prev != old);
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return 1;
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}
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/**
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* Free lock.
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*
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* \param dev DRM device.
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* \param lock lock.
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* \param context context.
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*
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* Resets the lock file pointer.
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* Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
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* waiting on the lock queue.
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*/
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int drm_lock_free(drm_device_t *dev,
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__volatile__ unsigned int *lock, unsigned int context)
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{
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unsigned int old, new, prev;
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dev->lock.filp = NULL;
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do {
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old = *lock;
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new = 0;
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prev = cmpxchg(lock, old, new);
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} while (prev != old);
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if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
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DRM_ERROR("%d freed heavyweight lock held by %d\n",
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context,
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_DRM_LOCKING_CONTEXT(old));
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return 1;
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}
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wake_up_interruptible(&dev->lock.lock_queue);
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return 0;
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}
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/**
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* If we get here, it means that the process has called DRM_IOCTL_LOCK
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* without calling DRM_IOCTL_UNLOCK.
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*
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* If the lock is not held, then let the signal proceed as usual. If the lock
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* is held, then set the contended flag and keep the signal blocked.
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*
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* \param priv pointer to a drm_sigdata structure.
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* \return one if the signal should be delivered normally, or zero if the
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* signal should be blocked.
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*/
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int drm_notifier(void *priv)
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{
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drm_sigdata_t *s = (drm_sigdata_t *)priv;
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unsigned int old, new, prev;
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/* Allow signal delivery if lock isn't held */
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if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
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|| _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context) return 1;
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/* Otherwise, set flag to force call to
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drmUnlock */
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do {
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old = s->lock->lock;
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new = old | _DRM_LOCK_CONT;
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prev = cmpxchg(&s->lock->lock, old, new);
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} while (prev != old);
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return 0;
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}
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