OMAPDSS: VENC: fix NULL pointer dereference in DSS2 VENC sysfs debug attr on OMAP4

[zen-stable.git] / drivers / gpu / drm / vmwgfx / vmwgfx_fence.c

/**************************************************************************
 *
 * Copyright © 2011 VMware, Inc., Palo Alto, CA., USA
 * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS 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"
#include "vmwgfx_drv.h"

#define VMW_FENCE_WRAP (1 << 31)

struct vmw_fence_manager {
        int num_fence_objects;
        struct vmw_private *dev_priv;
        spinlock_t lock;
        struct list_head fence_list;
        struct work_struct work;
        u32 user_fence_size;
        u32 fence_size;
        u32 event_fence_action_size;
        bool fifo_down;
        struct list_head cleanup_list;
        uint32_t pending_actions[VMW_ACTION_MAX];
        struct mutex goal_irq_mutex;
        bool goal_irq_on; /* Protected by @goal_irq_mutex */
        bool seqno_valid; /* Protected by @lock, and may not be set to true
                             without the @goal_irq_mutex held. */
};

struct vmw_user_fence {
        struct ttm_base_object base;
        struct vmw_fence_obj fence;
};

/**
 * struct vmw_event_fence_action - fence action that delivers a drm event.
 *
 * @e: A struct drm_pending_event that controls the event delivery.
 * @action: A struct vmw_fence_action to hook up to a fence.
 * @fence: A referenced pointer to the fence to keep it alive while @action
 * hangs on it.
 * @dev: Pointer to a struct drm_device so we can access the event stuff.
 * @kref: Both @e and @action has destructors, so we need to refcount.
 * @size: Size accounted for this object.
 * @tv_sec: If non-null, the variable pointed to will be assigned
 * current time tv_sec val when the fence signals.
 * @tv_usec: Must be set if @tv_sec is set, and the variable pointed to will
 * be assigned the current time tv_usec val when the fence signals.
 */
struct vmw_event_fence_action {
        struct drm_pending_event e;
        struct vmw_fence_action action;
        struct vmw_fence_obj *fence;
        struct drm_device *dev;
        struct kref kref;
        uint32_t size;
        uint32_t *tv_sec;
        uint32_t *tv_usec;
};

/**
 * Note on fencing subsystem usage of irqs:
 * Typically the vmw_fences_update function is called
 *
 * a) When a new fence seqno has been submitted by the fifo code.
 * b) On-demand when we have waiters. Sleeping waiters will switch on the
 * ANY_FENCE irq and call vmw_fences_update function each time an ANY_FENCE
 * irq is received. When the last fence waiter is gone, that IRQ is masked
 * away.
 *
 * In situations where there are no waiters and we don't submit any new fences,
 * fence objects may not be signaled. This is perfectly OK, since there are
 * no consumers of the signaled data, but that is NOT ok when there are fence
 * actions attached to a fence. The fencing subsystem then makes use of the
 * FENCE_GOAL irq and sets the fence goal seqno to that of the next fence
 * which has an action attached, and each time vmw_fences_update is called,
 * the subsystem makes sure the fence goal seqno is updated.
 *
 * The fence goal seqno irq is on as long as there are unsignaled fence
 * objects with actions attached to them.
 */

static void vmw_fence_obj_destroy_locked(struct kref *kref)
{
        struct vmw_fence_obj *fence =
                container_of(kref, struct vmw_fence_obj, kref);

        struct vmw_fence_manager *fman = fence->fman;
        unsigned int num_fences;

        list_del_init(&fence->head);
        num_fences = --fman->num_fence_objects;
        spin_unlock_irq(&fman->lock);
        if (fence->destroy)
                fence->destroy(fence);
        else
                kfree(fence);

        spin_lock_irq(&fman->lock);
}


/**
 * Execute signal actions on fences recently signaled.
 * This is done from a workqueue so we don't have to execute
 * signal actions from atomic context.
 */

static void vmw_fence_work_func(struct work_struct *work)
{
        struct vmw_fence_manager *fman =
                container_of(work, struct vmw_fence_manager, work);
        struct list_head list;
        struct vmw_fence_action *action, *next_action;
        bool seqno_valid;

        do {
                INIT_LIST_HEAD(&list);
                mutex_lock(&fman->goal_irq_mutex);

                spin_lock_irq(&fman->lock);
                list_splice_init(&fman->cleanup_list, &list);
                seqno_valid = fman->seqno_valid;
                spin_unlock_irq(&fman->lock);

                if (!seqno_valid && fman->goal_irq_on) {
                        fman->goal_irq_on = false;
                        vmw_goal_waiter_remove(fman->dev_priv);
                }
                mutex_unlock(&fman->goal_irq_mutex);

                if (list_empty(&list))
                        return;

                /*
                 * At this point, only we should be able to manipulate the
                 * list heads of the actions we have on the private list.
                 * hence fman::lock not held.
                 */

                list_for_each_entry_safe(action, next_action, &list, head) {
                        list_del_init(&action->head);
                        if (action->cleanup)
                                action->cleanup(action);
                }
        } while (1);
}

struct vmw_fence_manager *vmw_fence_manager_init(struct vmw_private *dev_priv)
{
        struct vmw_fence_manager *fman = kzalloc(sizeof(*fman), GFP_KERNEL);

        if (unlikely(fman == NULL))
                return NULL;

        fman->dev_priv = dev_priv;
        spin_lock_init(&fman->lock);
        INIT_LIST_HEAD(&fman->fence_list);
        INIT_LIST_HEAD(&fman->cleanup_list);
        INIT_WORK(&fman->work, &vmw_fence_work_func);
        fman->fifo_down = true;
        fman->user_fence_size = ttm_round_pot(sizeof(struct vmw_user_fence));
        fman->fence_size = ttm_round_pot(sizeof(struct vmw_fence_obj));
        fman->event_fence_action_size =
                ttm_round_pot(sizeof(struct vmw_event_fence_action));
        mutex_init(&fman->goal_irq_mutex);

        return fman;
}

void vmw_fence_manager_takedown(struct vmw_fence_manager *fman)
{
        unsigned long irq_flags;
        bool lists_empty;

        (void) cancel_work_sync(&fman->work);

        spin_lock_irqsave(&fman->lock, irq_flags);
        lists_empty = list_empty(&fman->fence_list) &&
                list_empty(&fman->cleanup_list);
        spin_unlock_irqrestore(&fman->lock, irq_flags);

        BUG_ON(!lists_empty);
        kfree(fman);
}

static int vmw_fence_obj_init(struct vmw_fence_manager *fman,
                              struct vmw_fence_obj *fence,
                              u32 seqno,
                              uint32_t mask,
                              void (*destroy) (struct vmw_fence_obj *fence))
{
        unsigned long irq_flags;
        unsigned int num_fences;
        int ret = 0;

        fence->seqno = seqno;
        INIT_LIST_HEAD(&fence->seq_passed_actions);
        fence->fman = fman;
        fence->signaled = 0;
        fence->signal_mask = mask;
        kref_init(&fence->kref);
        fence->destroy = destroy;
        init_waitqueue_head(&fence->queue);

        spin_lock_irqsave(&fman->lock, irq_flags);
        if (unlikely(fman->fifo_down)) {
                ret = -EBUSY;
                goto out_unlock;
        }
        list_add_tail(&fence->head, &fman->fence_list);
        num_fences = ++fman->num_fence_objects;

out_unlock:
        spin_unlock_irqrestore(&fman->lock, irq_flags);
        return ret;

}

struct vmw_fence_obj *vmw_fence_obj_reference(struct vmw_fence_obj *fence)
{
        if (unlikely(fence == NULL))
                return NULL;

        kref_get(&fence->kref);
        return fence;
}

/**
 * vmw_fence_obj_unreference
 *
 * Note that this function may not be entered with disabled irqs since
 * it may re-enable them in the destroy function.
 *
 */
void vmw_fence_obj_unreference(struct vmw_fence_obj **fence_p)
{
        struct vmw_fence_obj *fence = *fence_p;
        struct vmw_fence_manager *fman;

        if (unlikely(fence == NULL))
                return;

        fman = fence->fman;
        *fence_p = NULL;
        spin_lock_irq(&fman->lock);
        BUG_ON(atomic_read(&fence->kref.refcount) == 0);
        kref_put(&fence->kref, vmw_fence_obj_destroy_locked);
        spin_unlock_irq(&fman->lock);
}

void vmw_fences_perform_actions(struct vmw_fence_manager *fman,
                                struct list_head *list)
{
        struct vmw_fence_action *action, *next_action;

        list_for_each_entry_safe(action, next_action, list, head) {
                list_del_init(&action->head);
                fman->pending_actions[action->type]--;
                if (action->seq_passed != NULL)
                        action->seq_passed(action);

                /*
                 * Add the cleanup action to the cleanup list so that
                 * it will be performed by a worker task.
                 */

                list_add_tail(&action->head, &fman->cleanup_list);
        }
}

/**
 * vmw_fence_goal_new_locked - Figure out a new device fence goal
 * seqno if needed.
 *
 * @fman: Pointer to a fence manager.
 * @passed_seqno: The seqno the device currently signals as passed.
 *
 * This function should be called with the fence manager lock held.
 * It is typically called when we have a new passed_seqno, and
 * we might need to update the fence goal. It checks to see whether
 * the current fence goal has already passed, and, in that case,
 * scans through all unsignaled fences to get the next fence object with an
 * action attached, and sets the seqno of that fence as a new fence goal.
 *
 * returns true if the device goal seqno was updated. False otherwise.
 */
static bool vmw_fence_goal_new_locked(struct vmw_fence_manager *fman,
                                      u32 passed_seqno)
{
        u32 goal_seqno;
        __le32 __iomem *fifo_mem;
        struct vmw_fence_obj *fence;

        if (likely(!fman->seqno_valid))
                return false;

        fifo_mem = fman->dev_priv->mmio_virt;
        goal_seqno = ioread32(fifo_mem + SVGA_FIFO_FENCE_GOAL);
        if (likely(passed_seqno - goal_seqno >= VMW_FENCE_WRAP))
                return false;

        fman->seqno_valid = false;
        list_for_each_entry(fence, &fman->fence_list, head) {
                if (!list_empty(&fence->seq_passed_actions)) {
                        fman->seqno_valid = true;
                        iowrite32(fence->seqno,
                                  fifo_mem + SVGA_FIFO_FENCE_GOAL);
                        break;
                }
        }

        return true;
}


/**
 * vmw_fence_goal_check_locked - Replace the device fence goal seqno if
 * needed.
 *
 * @fence: Pointer to a struct vmw_fence_obj the seqno of which should be
 * considered as a device fence goal.
 *
 * This function should be called with the fence manager lock held.
 * It is typically called when an action has been attached to a fence to
 * check whether the seqno of that fence should be used for a fence
 * goal interrupt. This is typically needed if the current fence goal is
 * invalid, or has a higher seqno than that of the current fence object.
 *
 * returns true if the device goal seqno was updated. False otherwise.
 */
static bool vmw_fence_goal_check_locked(struct vmw_fence_obj *fence)
{
        u32 goal_seqno;
        __le32 __iomem *fifo_mem;

        if (fence->signaled & DRM_VMW_FENCE_FLAG_EXEC)
                return false;

        fifo_mem = fence->fman->dev_priv->mmio_virt;
        goal_seqno = ioread32(fifo_mem + SVGA_FIFO_FENCE_GOAL);
        if (likely(fence->fman->seqno_valid &&
                   goal_seqno - fence->seqno < VMW_FENCE_WRAP))
                return false;

        iowrite32(fence->seqno, fifo_mem + SVGA_FIFO_FENCE_GOAL);
        fence->fman->seqno_valid = true;

        return true;
}

void vmw_fences_update(struct vmw_fence_manager *fman)
{
        unsigned long flags;
        struct vmw_fence_obj *fence, *next_fence;
        struct list_head action_list;
        bool needs_rerun;
        uint32_t seqno, new_seqno;
        __le32 __iomem *fifo_mem = fman->dev_priv->mmio_virt;

        seqno = ioread32(fifo_mem + SVGA_FIFO_FENCE);
rerun:
        spin_lock_irqsave(&fman->lock, flags);
        list_for_each_entry_safe(fence, next_fence, &fman->fence_list, head) {
                if (seqno - fence->seqno < VMW_FENCE_WRAP) {
                        list_del_init(&fence->head);
                        fence->signaled |= DRM_VMW_FENCE_FLAG_EXEC;
                        INIT_LIST_HEAD(&action_list);
                        list_splice_init(&fence->seq_passed_actions,
                                         &action_list);
                        vmw_fences_perform_actions(fman, &action_list);
                        wake_up_all(&fence->queue);
                } else
                        break;
        }

        needs_rerun = vmw_fence_goal_new_locked(fman, seqno);

        if (!list_empty(&fman->cleanup_list))
                (void) schedule_work(&fman->work);
        spin_unlock_irqrestore(&fman->lock, flags);

        /*
         * Rerun if the fence goal seqno was updated, and the
         * hardware might have raced with that update, so that
         * we missed a fence_goal irq.
         */

        if (unlikely(needs_rerun)) {
                new_seqno = ioread32(fifo_mem + SVGA_FIFO_FENCE);
                if (new_seqno != seqno) {
                        seqno = new_seqno;
                        goto rerun;
                }
        }
}

bool vmw_fence_obj_signaled(struct vmw_fence_obj *fence,
                            uint32_t flags)
{
        struct vmw_fence_manager *fman = fence->fman;
        unsigned long irq_flags;
        uint32_t signaled;

        spin_lock_irqsave(&fman->lock, irq_flags);
        signaled = fence->signaled;
        spin_unlock_irqrestore(&fman->lock, irq_flags);

        flags &= fence->signal_mask;
        if ((signaled & flags) == flags)
                return 1;

        if ((signaled & DRM_VMW_FENCE_FLAG_EXEC) == 0)
                vmw_fences_update(fman);

        spin_lock_irqsave(&fman->lock, irq_flags);
        signaled = fence->signaled;
        spin_unlock_irqrestore(&fman->lock, irq_flags);

        return ((signaled & flags) == flags);
}

int vmw_fence_obj_wait(struct vmw_fence_obj *fence,
                       uint32_t flags, bool lazy,
                       bool interruptible, unsigned long timeout)
{
        struct vmw_private *dev_priv = fence->fman->dev_priv;
        long ret;

        if (likely(vmw_fence_obj_signaled(fence, flags)))
                return 0;

        vmw_fifo_ping_host(dev_priv, SVGA_SYNC_GENERIC);
        vmw_seqno_waiter_add(dev_priv);

        if (interruptible)
                ret = wait_event_interruptible_timeout
                        (fence->queue,
                         vmw_fence_obj_signaled(fence, flags),
                         timeout);
        else
                ret = wait_event_timeout
                        (fence->queue,
                         vmw_fence_obj_signaled(fence, flags),
                         timeout);

        vmw_seqno_waiter_remove(dev_priv);

        if (unlikely(ret == 0))
                ret = -EBUSY;
        else if (likely(ret > 0))
                ret = 0;

        return ret;
}

void vmw_fence_obj_flush(struct vmw_fence_obj *fence)
{
        struct vmw_private *dev_priv = fence->fman->dev_priv;

        vmw_fifo_ping_host(dev_priv, SVGA_SYNC_GENERIC);
}

static void vmw_fence_destroy(struct vmw_fence_obj *fence)
{
        struct vmw_fence_manager *fman = fence->fman;

        kfree(fence);
        /*
         * Free kernel space accounting.
         */
        ttm_mem_global_free(vmw_mem_glob(fman->dev_priv),
                            fman->fence_size);
}

int vmw_fence_create(struct vmw_fence_manager *fman,
                     uint32_t seqno,
                     uint32_t mask,
                     struct vmw_fence_obj **p_fence)
{
        struct ttm_mem_global *mem_glob = vmw_mem_glob(fman->dev_priv);
        struct vmw_fence_obj *fence;
        int ret;

        ret = ttm_mem_global_alloc(mem_glob, fman->fence_size,
                                   false, false);
        if (unlikely(ret != 0))
                return ret;

        fence = kzalloc(sizeof(*fence), GFP_KERNEL);
        if (unlikely(fence == NULL)) {
                ret = -ENOMEM;
                goto out_no_object;
        }

        ret = vmw_fence_obj_init(fman, fence, seqno, mask,
                                 vmw_fence_destroy);
        if (unlikely(ret != 0))
                goto out_err_init;

        *p_fence = fence;
        return 0;

out_err_init:
        kfree(fence);
out_no_object:
        ttm_mem_global_free(mem_glob, fman->fence_size);
        return ret;
}


static void vmw_user_fence_destroy(struct vmw_fence_obj *fence)
{
        struct vmw_user_fence *ufence =
                container_of(fence, struct vmw_user_fence, fence);
        struct vmw_fence_manager *fman = fence->fman;

        kfree(ufence);
        /*
         * Free kernel space accounting.
         */
        ttm_mem_global_free(vmw_mem_glob(fman->dev_priv),
                            fman->user_fence_size);
}

static void vmw_user_fence_base_release(struct ttm_base_object **p_base)
{
        struct ttm_base_object *base = *p_base;
        struct vmw_user_fence *ufence =
                container_of(base, struct vmw_user_fence, base);
        struct vmw_fence_obj *fence = &ufence->fence;

        *p_base = NULL;
        vmw_fence_obj_unreference(&fence);
}

int vmw_user_fence_create(struct drm_file *file_priv,
                          struct vmw_fence_manager *fman,
                          uint32_t seqno,
                          uint32_t mask,
                          struct vmw_fence_obj **p_fence,
                          uint32_t *p_handle)
{
        struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
        struct vmw_user_fence *ufence;
        struct vmw_fence_obj *tmp;
        struct ttm_mem_global *mem_glob = vmw_mem_glob(fman->dev_priv);
        int ret;

        /*
         * Kernel memory space accounting, since this object may
         * be created by a user-space request.
         */

        ret = ttm_mem_global_alloc(mem_glob, fman->user_fence_size,
                                   false, false);
        if (unlikely(ret != 0))
                return ret;

        ufence = kzalloc(sizeof(*ufence), GFP_KERNEL);
        if (unlikely(ufence == NULL)) {
                ret = -ENOMEM;
                goto out_no_object;
        }

        ret = vmw_fence_obj_init(fman, &ufence->fence, seqno,
                                 mask, vmw_user_fence_destroy);
        if (unlikely(ret != 0)) {
                kfree(ufence);
                goto out_no_object;
        }

        /*
         * The base object holds a reference which is freed in
         * vmw_user_fence_base_release.
         */
        tmp = vmw_fence_obj_reference(&ufence->fence);
        ret = ttm_base_object_init(tfile, &ufence->base, false,
                                   VMW_RES_FENCE,
                                   &vmw_user_fence_base_release, NULL);


        if (unlikely(ret != 0)) {
                /*
                 * Free the base object's reference
                 */
                vmw_fence_obj_unreference(&tmp);
                goto out_err;
        }

        *p_fence = &ufence->fence;
        *p_handle = ufence->base.hash.key;

        return 0;
out_err:
        tmp = &ufence->fence;
        vmw_fence_obj_unreference(&tmp);
out_no_object:
        ttm_mem_global_free(mem_glob, fman->user_fence_size);
        return ret;
}


/**
 * vmw_fence_fifo_down - signal all unsignaled fence objects.
 */

void vmw_fence_fifo_down(struct vmw_fence_manager *fman)
{
        unsigned long irq_flags;
        struct list_head action_list;
        int ret;

        /*
         * The list may be altered while we traverse it, so always
         * restart when we've released the fman->lock.
         */

        spin_lock_irqsave(&fman->lock, irq_flags);
        fman->fifo_down = true;
        while (!list_empty(&fman->fence_list)) {
                struct vmw_fence_obj *fence =
                        list_entry(fman->fence_list.prev, struct vmw_fence_obj,
                                   head);
                kref_get(&fence->kref);
                spin_unlock_irq(&fman->lock);

                ret = vmw_fence_obj_wait(fence, fence->signal_mask,
                                         false, false,
                                         VMW_FENCE_WAIT_TIMEOUT);

                if (unlikely(ret != 0)) {
                        list_del_init(&fence->head);
                        fence->signaled |= DRM_VMW_FENCE_FLAG_EXEC;
                        INIT_LIST_HEAD(&action_list);
                        list_splice_init(&fence->seq_passed_actions,
                                         &action_list);
                        vmw_fences_perform_actions(fman, &action_list);
                        wake_up_all(&fence->queue);
                }

                spin_lock_irq(&fman->lock);

                BUG_ON(!list_empty(&fence->head));
                kref_put(&fence->kref, vmw_fence_obj_destroy_locked);
        }
        spin_unlock_irqrestore(&fman->lock, irq_flags);
}

void vmw_fence_fifo_up(struct vmw_fence_manager *fman)
{
        unsigned long irq_flags;

        spin_lock_irqsave(&fman->lock, irq_flags);
        fman->fifo_down = false;
        spin_unlock_irqrestore(&fman->lock, irq_flags);
}


int vmw_fence_obj_wait_ioctl(struct drm_device *dev, void *data,
                             struct drm_file *file_priv)
{
        struct drm_vmw_fence_wait_arg *arg =
            (struct drm_vmw_fence_wait_arg *)data;
        unsigned long timeout;
        struct ttm_base_object *base;
        struct vmw_fence_obj *fence;
        struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
        int ret;
        uint64_t wait_timeout = ((uint64_t)arg->timeout_us * HZ);

        /*
         * 64-bit division not present on 32-bit systems, so do an
         * approximation. (Divide by 1000000).
         */

        wait_timeout = (wait_timeout >> 20) + (wait_timeout >> 24) -
          (wait_timeout >> 26);

        if (!arg->cookie_valid) {
                arg->cookie_valid = 1;
                arg->kernel_cookie = jiffies + wait_timeout;
        }

        base = ttm_base_object_lookup(tfile, arg->handle);
        if (unlikely(base == NULL)) {
                printk(KERN_ERR "Wait invalid fence object handle "
                       "0x%08lx.\n",
                       (unsigned long)arg->handle);
                return -EINVAL;
        }

        fence = &(container_of(base, struct vmw_user_fence, base)->fence);

        timeout = jiffies;
        if (time_after_eq(timeout, (unsigned long)arg->kernel_cookie)) {
                ret = ((vmw_fence_obj_signaled(fence, arg->flags)) ?
                       0 : -EBUSY);
                goto out;
        }

        timeout = (unsigned long)arg->kernel_cookie - timeout;

        ret = vmw_fence_obj_wait(fence, arg->flags, arg->lazy, true, timeout);

out:
        ttm_base_object_unref(&base);

        /*
         * Optionally unref the fence object.
         */

        if (ret == 0 && (arg->wait_options & DRM_VMW_WAIT_OPTION_UNREF))
                return ttm_ref_object_base_unref(tfile, arg->handle,
                                                 TTM_REF_USAGE);
        return ret;
}

int vmw_fence_obj_signaled_ioctl(struct drm_device *dev, void *data,
                                 struct drm_file *file_priv)
{
        struct drm_vmw_fence_signaled_arg *arg =
                (struct drm_vmw_fence_signaled_arg *) data;
        struct ttm_base_object *base;
        struct vmw_fence_obj *fence;
        struct vmw_fence_manager *fman;
        struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
        struct vmw_private *dev_priv = vmw_priv(dev);

        base = ttm_base_object_lookup(tfile, arg->handle);
        if (unlikely(base == NULL)) {
                printk(KERN_ERR "Fence signaled invalid fence object handle "
                       "0x%08lx.\n",
                       (unsigned long)arg->handle);
                return -EINVAL;
        }

        fence = &(container_of(base, struct vmw_user_fence, base)->fence);
        fman = fence->fman;

        arg->signaled = vmw_fence_obj_signaled(fence, arg->flags);
        spin_lock_irq(&fman->lock);

        arg->signaled_flags = fence->signaled;
        arg->passed_seqno = dev_priv->last_read_seqno;
        spin_unlock_irq(&fman->lock);

        ttm_base_object_unref(&base);

        return 0;
}


int vmw_fence_obj_unref_ioctl(struct drm_device *dev, void *data,
                              struct drm_file *file_priv)
{
        struct drm_vmw_fence_arg *arg =
                (struct drm_vmw_fence_arg *) data;

        return ttm_ref_object_base_unref(vmw_fpriv(file_priv)->tfile,
                                         arg->handle,
                                         TTM_REF_USAGE);
}

/**
 * vmw_event_fence_action_destroy
 *
 * @kref: The struct kref embedded in a struct vmw_event_fence_action.
 *
 * The vmw_event_fence_action destructor that may be called either after
 * the fence action cleanup, or when the event is delivered.
 * It frees both the vmw_event_fence_action struct and the actual
 * event structure copied to user-space.
 */
static void vmw_event_fence_action_destroy(struct kref *kref)
{
        struct vmw_event_fence_action *eaction =
                container_of(kref, struct vmw_event_fence_action, kref);
        struct ttm_mem_global *mem_glob =
                vmw_mem_glob(vmw_priv(eaction->dev));
        uint32_t size = eaction->size;

        kfree(eaction->e.event);
        kfree(eaction);
        ttm_mem_global_free(mem_glob, size);
}


/**
 * vmw_event_fence_action_delivered
 *
 * @e: The struct drm_pending_event embedded in a struct
 * vmw_event_fence_action.
 *
 * The struct drm_pending_event destructor that is called by drm
 * once the event is delivered. Since we don't know whether this function
 * will be called before or after the fence action destructor, we
 * free a refcount and destroy if it becomes zero.
 */
static void vmw_event_fence_action_delivered(struct drm_pending_event *e)
{
        struct vmw_event_fence_action *eaction =
                container_of(e, struct vmw_event_fence_action, e);

        kref_put(&eaction->kref, vmw_event_fence_action_destroy);
}


/**
 * vmw_event_fence_action_seq_passed
 *
 * @action: The struct vmw_fence_action embedded in a struct
 * vmw_event_fence_action.
 *
 * This function is called when the seqno of the fence where @action is
 * attached has passed. It queues the event on the submitter's event list.
 * This function is always called from atomic context, and may be called
 * from irq context. It ups a refcount reflecting that we now have two
 * destructors.
 */
static void vmw_event_fence_action_seq_passed(struct vmw_fence_action *action)
{
        struct vmw_event_fence_action *eaction =
                container_of(action, struct vmw_event_fence_action, action);
        struct drm_device *dev = eaction->dev;
        struct drm_file *file_priv = eaction->e.file_priv;
        unsigned long irq_flags;

        kref_get(&eaction->kref);
        spin_lock_irqsave(&dev->event_lock, irq_flags);

        if (likely(eaction->tv_sec != NULL)) {
                struct timeval tv;

                do_gettimeofday(&tv);
                *eaction->tv_sec = tv.tv_sec;
                *eaction->tv_usec = tv.tv_usec;
        }

        list_add_tail(&eaction->e.link, &file_priv->event_list);
        wake_up_all(&file_priv->event_wait);
        spin_unlock_irqrestore(&dev->event_lock, irq_flags);
}

/**
 * vmw_event_fence_action_cleanup
 *
 * @action: The struct vmw_fence_action embedded in a struct
 * vmw_event_fence_action.
 *
 * This function is the struct vmw_fence_action destructor. It's typically
 * called from a workqueue.
 */
static void vmw_event_fence_action_cleanup(struct vmw_fence_action *action)
{
        struct vmw_event_fence_action *eaction =
                container_of(action, struct vmw_event_fence_action, action);

        vmw_fence_obj_unreference(&eaction->fence);
        kref_put(&eaction->kref, vmw_event_fence_action_destroy);
}


/**
 * vmw_fence_obj_add_action - Add an action to a fence object.
 *
 * @fence - The fence object.
 * @action - The action to add.
 *
 * Note that the action callbacks may be executed before this function
 * returns.
 */
void vmw_fence_obj_add_action(struct vmw_fence_obj *fence,
                              struct vmw_fence_action *action)
{
        struct vmw_fence_manager *fman = fence->fman;
        unsigned long irq_flags;
        bool run_update = false;

        mutex_lock(&fman->goal_irq_mutex);
        spin_lock_irqsave(&fman->lock, irq_flags);

        fman->pending_actions[action->type]++;
        if (fence->signaled & DRM_VMW_FENCE_FLAG_EXEC) {
                struct list_head action_list;

                INIT_LIST_HEAD(&action_list);
                list_add_tail(&action->head, &action_list);
                vmw_fences_perform_actions(fman, &action_list);
        } else {
                list_add_tail(&action->head, &fence->seq_passed_actions);

                /*
                 * This function may set fman::seqno_valid, so it must
                 * be run with the goal_irq_mutex held.
                 */
                run_update = vmw_fence_goal_check_locked(fence);
        }

        spin_unlock_irqrestore(&fman->lock, irq_flags);

        if (run_update) {
                if (!fman->goal_irq_on) {
                        fman->goal_irq_on = true;
                        vmw_goal_waiter_add(fman->dev_priv);
                }
                vmw_fences_update(fman);
        }
        mutex_unlock(&fman->goal_irq_mutex);

}

/**
 * vmw_event_fence_action_create - Post an event for sending when a fence
 * object seqno has passed.
 *
 * @file_priv: The file connection on which the event should be posted.
 * @fence: The fence object on which to post the event.
 * @event: Event to be posted. This event should've been alloced
 * using k[mz]alloc, and should've been completely initialized.
 * @interruptible: Interruptible waits if possible.
 *
 * As a side effect, the object pointed to by @event may have been
 * freed when this function returns. If this function returns with
 * an error code, the caller needs to free that object.
 */

int vmw_event_fence_action_create(struct drm_file *file_priv,
                                  struct vmw_fence_obj *fence,
                                  struct drm_event *event,
                                  uint32_t *tv_sec,
                                  uint32_t *tv_usec,
                                  bool interruptible)
{
        struct vmw_event_fence_action *eaction;
        struct ttm_mem_global *mem_glob =
                vmw_mem_glob(fence->fman->dev_priv);
        struct vmw_fence_manager *fman = fence->fman;
        uint32_t size = fman->event_fence_action_size +
                ttm_round_pot(event->length);
        int ret;

        /*
         * Account for internal structure size as well as the
         * event size itself.
         */

        ret = ttm_mem_global_alloc(mem_glob, size, false, interruptible);
        if (unlikely(ret != 0))
                return ret;

        eaction = kzalloc(sizeof(*eaction), GFP_KERNEL);
        if (unlikely(eaction == NULL)) {
                ttm_mem_global_free(mem_glob, size);
                return -ENOMEM;
        }

        eaction->e.event = event;
        eaction->e.file_priv = file_priv;
        eaction->e.destroy = vmw_event_fence_action_delivered;

        eaction->action.seq_passed = vmw_event_fence_action_seq_passed;
        eaction->action.cleanup = vmw_event_fence_action_cleanup;
        eaction->action.type = VMW_ACTION_EVENT;

        eaction->fence = vmw_fence_obj_reference(fence);
        eaction->dev = fman->dev_priv->dev;
        eaction->size = size;
        eaction->tv_sec = tv_sec;
        eaction->tv_usec = tv_usec;

        kref_init(&eaction->kref);
        vmw_fence_obj_add_action(fence, &eaction->action);

        return 0;
}

int vmw_fence_event_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file_priv)
{
        struct vmw_private *dev_priv = vmw_priv(dev);
        struct drm_vmw_fence_event_arg *arg =
                (struct drm_vmw_fence_event_arg *) data;
        struct vmw_fence_obj *fence = NULL;
        struct vmw_fpriv *vmw_fp = vmw_fpriv(file_priv);
        struct drm_vmw_fence_rep __user *user_fence_rep =
                (struct drm_vmw_fence_rep __user *)(unsigned long)
                arg->fence_rep;
        uint32_t handle;
        unsigned long irq_flags;
        struct drm_vmw_event_fence *event;
        int ret;

        /*
         * Look up an existing fence object,
         * and if user-space wants a new reference,
         * add one.
         */
        if (arg->handle) {
                struct ttm_base_object *base =
                        ttm_base_object_lookup(vmw_fp->tfile, arg->handle);

                if (unlikely(base == NULL)) {
                        DRM_ERROR("Fence event invalid fence object handle "
                                  "0x%08lx.\n",
                                  (unsigned long)arg->handle);
                        return -EINVAL;
                }
                fence = &(container_of(base, struct vmw_user_fence,
                                       base)->fence);
                (void) vmw_fence_obj_reference(fence);

                if (user_fence_rep != NULL) {
                        bool existed;

                        ret = ttm_ref_object_add(vmw_fp->tfile, base,
                                                 TTM_REF_USAGE, &existed);
                        if (unlikely(ret != 0)) {
                                DRM_ERROR("Failed to reference a fence "
                                          "object.\n");
                                goto out_no_ref_obj;
                        }
                        handle = base->hash.key;
                }
                ttm_base_object_unref(&base);
        }

        /*
         * Create a new fence object.
         */
        if (!fence) {
                ret = vmw_execbuf_fence_commands(file_priv, dev_priv,
                                                 &fence,
                                                 (user_fence_rep) ?
                                                 &handle : NULL);
                if (unlikely(ret != 0)) {
                        DRM_ERROR("Fence event failed to create fence.\n");
                        return ret;
                }
        }

        BUG_ON(fence == NULL);

        spin_lock_irqsave(&dev->event_lock, irq_flags);

        ret = (file_priv->event_space < sizeof(*event)) ? -EBUSY : 0;
        if (likely(ret == 0))
                file_priv->event_space -= sizeof(*event);

        spin_unlock_irqrestore(&dev->event_lock, irq_flags);

        if (unlikely(ret != 0)) {
                DRM_ERROR("Failed to allocate event space for this file.\n");
                goto out_no_event_space;
        }

        event = kzalloc(sizeof(*event), GFP_KERNEL);
        if (unlikely(event == NULL)) {
                DRM_ERROR("Failed to allocate an event.\n");
                goto out_no_event;
        }

        event->base.type = DRM_VMW_EVENT_FENCE_SIGNALED;
        event->base.length = sizeof(*event);
        event->user_data = arg->user_data;

        if (arg->flags & DRM_VMW_FE_FLAG_REQ_TIME)
                ret = vmw_event_fence_action_create(file_priv, fence,
                                                    &event->base,
                                                    &event->tv_sec,
                                                    &event->tv_usec,
                                                    true);
        else
                ret = vmw_event_fence_action_create(file_priv, fence,
                                                    &event->base,
                                                    NULL,
                                                    NULL,
                                                    true);

        if (unlikely(ret != 0)) {
                if (ret != -ERESTARTSYS)
                        DRM_ERROR("Failed to attach event to fence.\n");
                goto out_no_attach;
        }

        vmw_execbuf_copy_fence_user(dev_priv, vmw_fp, 0, user_fence_rep, fence,
                                    handle);
        vmw_fence_obj_unreference(&fence);
        return 0;
out_no_attach:
        kfree(event);
out_no_event:
        spin_lock_irqsave(&dev->event_lock, irq_flags);
        file_priv->event_space += sizeof(*event);
        spin_unlock_irqrestore(&dev->event_lock, irq_flags);
out_no_event_space:
        if (user_fence_rep != NULL)
                ttm_ref_object_base_unref(vmw_fpriv(file_priv)->tfile,
                                          handle, TTM_REF_USAGE);
out_no_ref_obj:
        vmw_fence_obj_unreference(&fence);
        return ret;
}