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-rw-r--r--drivers/char/drm/drm_lock.c303
1 files changed, 303 insertions, 0 deletions
diff --git a/drivers/char/drm/drm_lock.c b/drivers/char/drm/drm_lock.c
new file mode 100644
index 000000000000..d0d6fc661625
--- /dev/null
+++ b/drivers/char/drm/drm_lock.c
@@ -0,0 +1,303 @@
+/**
+ * \file drm_lock.h
+ * 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"
+
+/**
+ * Lock ioctl.
+ *
+ * \param inode device inode.
+ * \param filp file pointer.
+ * \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 inode *inode, struct file *filp,
+ unsigned int cmd, unsigned long arg )
+{
+ drm_file_t *priv = filp->private_data;
+ drm_device_t *dev = priv->head->dev;
+ DECLARE_WAITQUEUE( entry, current );
+ drm_lock_t lock;
+ int ret = 0;
+
+ ++priv->lock_count;
+
+ if ( copy_from_user( &lock, (drm_lock_t __user *)arg, sizeof(lock) ) )
+ return -EFAULT;
+
+ if ( lock.context == DRM_KERNEL_CONTEXT ) {
+ DRM_ERROR( "Process %d using kernel context %d\n",
+ current->pid, lock.context );
+ return -EINVAL;
+ }
+
+ DRM_DEBUG( "%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
+ lock.context, current->pid,
+ 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 );
+ for (;;) {
+ __set_current_state(TASK_INTERRUPTIBLE);
+ if ( !dev->lock.hw_lock ) {
+ /* Device has been unregistered */
+ ret = -EINTR;
+ break;
+ }
+ if ( drm_lock_take( &dev->lock.hw_lock->lock,
+ lock.context ) ) {
+ dev->lock.filp = filp;
+ dev->lock.lock_time = jiffies;
+ atomic_inc( &dev->counts[_DRM_STAT_LOCKS] );
+ break; /* Got lock */
+ }
+
+ /* Contention */
+ schedule();
+ if ( signal_pending( current ) ) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+ }
+ __set_current_state(TASK_RUNNING);
+ remove_wait_queue( &dev->lock.lock_queue, &entry );
+
+ 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 ))
+ return dev->driver->dma_quiescent(dev);
+
+ /* dev->driver->kernel_context_switch isn't used by any of the x86
+ * drivers but is used by the Sparc driver.
+ */
+
+ if (dev->driver->kernel_context_switch &&
+ dev->last_context != lock.context) {
+ dev->driver->kernel_context_switch(dev, dev->last_context,
+ lock.context);
+ }
+ DRM_DEBUG( "%d %s\n", lock.context, ret ? "interrupted" : "has lock" );
+
+ return ret;
+}
+
+/**
+ * Unlock ioctl.
+ *
+ * \param inode device inode.
+ * \param filp file pointer.
+ * \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 inode *inode, struct file *filp,
+ unsigned int cmd, unsigned long arg )
+{
+ drm_file_t *priv = filp->private_data;
+ drm_device_t *dev = priv->head->dev;
+ drm_lock_t lock;
+
+ if ( copy_from_user( &lock, (drm_lock_t __user *)arg, sizeof(lock) ) )
+ return -EFAULT;
+
+ if ( lock.context == DRM_KERNEL_CONTEXT ) {
+ DRM_ERROR( "Process %d using kernel context %d\n",
+ current->pid, 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.
+ */
+ if (dev->driver->kernel_context_switch_unlock)
+ dev->driver->kernel_context_switch_unlock(dev, &lock);
+ else {
+ drm_lock_transfer( dev, &dev->lock.hw_lock->lock,
+ DRM_KERNEL_CONTEXT );
+
+ if ( drm_lock_free( dev, &dev->lock.hw_lock->lock,
+ DRM_KERNEL_CONTEXT ) ) {
+ DRM_ERROR( "\n" );
+ }
+ }
+
+ 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(__volatile__ unsigned int *lock, unsigned int context)
+{
+ unsigned int old, new, prev;
+
+ do {
+ old = *lock;
+ if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
+ else new = context | _DRM_LOCK_HELD;
+ prev = cmpxchg(lock, old, new);
+ } while (prev != old);
+ 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 (new == (context | _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.
+ */
+int drm_lock_transfer(drm_device_t *dev,
+ __volatile__ unsigned int *lock, unsigned int context)
+{
+ unsigned int old, new, prev;
+
+ dev->lock.filp = 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(drm_device_t *dev,
+ __volatile__ unsigned int *lock, unsigned int context)
+{
+ unsigned int old, new, prev;
+
+ dev->lock.filp = NULL;
+ do {
+ old = *lock;
+ new = 0;
+ 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(&dev->lock.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.
+ */
+int drm_notifier(void *priv)
+{
+ drm_sigdata_t *s = (drm_sigdata_t *)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;
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.