--- /dev/null
+/**
+ * \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>
+#include "drm_legacy.h"
+#include "drm_internal.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_legacy_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, &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_legacy_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_legacy_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.
+ */
+static
+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_legacy_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_device 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_device *dev = priv;
+ struct drm_hw_lock *lock = dev->sigdata.lock;
+ unsigned int old, new, prev;
+
+ /* Allow signal delivery if lock isn't held */
+ if (!lock || !_DRM_LOCK_IS_HELD(lock->lock)
+ || _DRM_LOCKING_CONTEXT(lock->lock) != dev->sigdata.context)
+ return 1;
+
+ /* Otherwise, set flag to force call to
+ drmUnlock */
+ do {
+ old = lock->lock;
+ new = old | _DRM_LOCK_CONT;
+ prev = cmpxchg(&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_legacy_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_legacy_idlelock_take);
+
+void drm_legacy_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_legacy_idlelock_release);
+
+int drm_legacy_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);
+}
Code Review / kvmfornfv.git / blobdiff