Linux-libre 4.8.2-gnupck-4.8.2-gnu

4 files changed, 483 insertions, 113 deletions

diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
index 3f4c7b842..bfcdea133 100644
--- a/drivers/gpu/drm/vgem/Makefile
+++ b/drivers/gpu/drm/vgem/Makefile
@@ -1,4 +1,4 @@
 ccflags-y := -Iinclude/drm
-vgem-y := vgem_drv.o
+vgem-y := vgem_drv.o vgem_fence.o
 
 obj-$(CONFIG_DRM_VGEM)	+= vgem.o
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 341f9be3d..c15bafb06 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -42,81 +42,38 @@
 #define DRIVER_MAJOR	1
 #define DRIVER_MINOR	0
 
-void vgem_gem_put_pages(struct drm_vgem_gem_object *obj)
-{
-	drm_gem_put_pages(&obj->base, obj->pages, false, false);
-	obj->pages = NULL;
-}
-
 static void vgem_gem_free_object(struct drm_gem_object *obj)
 {
 	struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
 
-	drm_gem_free_mmap_offset(obj);
-
-	if (vgem_obj->use_dma_buf && obj->dma_buf) {
-		dma_buf_put(obj->dma_buf);
-		obj->dma_buf = NULL;
-	}
-
 	drm_gem_object_release(obj);
-
-	if (vgem_obj->pages)
-		vgem_gem_put_pages(vgem_obj);
-
-	vgem_obj->pages = NULL;
-
 	kfree(vgem_obj);
 }
 
-int vgem_gem_get_pages(struct drm_vgem_gem_object *obj)
-{
-	struct page **pages;
-
-	if (obj->pages || obj->use_dma_buf)
-		return 0;
-
-	pages = drm_gem_get_pages(&obj->base);
-	if (IS_ERR(pages)) {
-		return PTR_ERR(pages);
-	}
-
-	obj->pages = pages;
-
-	return 0;
-}
-
 static int vgem_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct drm_vgem_gem_object *obj = vma->vm_private_data;
-	loff_t num_pages;
-	pgoff_t page_offset;
-	int ret;
-
 	/* We don't use vmf->pgoff since that has the fake offset */
-	page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
-		PAGE_SHIFT;
-
-	num_pages = DIV_ROUND_UP(obj->base.size, PAGE_SIZE);
-
-	if (page_offset > num_pages)
-		return VM_FAULT_SIGBUS;
-
-	ret = vm_insert_page(vma, (unsigned long)vmf->virtual_address,
-			     obj->pages[page_offset]);
-	switch (ret) {
-	case 0:
-		return VM_FAULT_NOPAGE;
-	case -ENOMEM:
-		return VM_FAULT_OOM;
-	case -EBUSY:
-		return VM_FAULT_RETRY;
-	case -EFAULT:
-	case -EINVAL:
-		return VM_FAULT_SIGBUS;
-	default:
-		WARN_ON(1);
-		return VM_FAULT_SIGBUS;
+	unsigned long vaddr = (unsigned long)vmf->virtual_address;
+	struct page *page;
+
+	page = shmem_read_mapping_page(file_inode(obj->base.filp)->i_mapping,
+				       (vaddr - vma->vm_start) >> PAGE_SHIFT);
+	if (!IS_ERR(page)) {
+		vmf->page = page;
+		return 0;
+	} else switch (PTR_ERR(page)) {
+		case -ENOSPC:
+		case -ENOMEM:
+			return VM_FAULT_OOM;
+		case -EBUSY:
+			return VM_FAULT_RETRY;
+		case -EFAULT:
+		case -EINVAL:
+			return VM_FAULT_SIGBUS;
+		default:
+			WARN_ON_ONCE(PTR_ERR(page));
+			return VM_FAULT_SIGBUS;
 	}
 }
 
@@ -126,6 +83,34 @@ static const struct vm_operations_struct vgem_gem_vm_ops = {
 	.close = drm_gem_vm_close,
 };
 
+static int vgem_open(struct drm_device *dev, struct drm_file *file)
+{
+	struct vgem_file *vfile;
+	int ret;
+
+	vfile = kzalloc(sizeof(*vfile), GFP_KERNEL);
+	if (!vfile)
+		return -ENOMEM;
+
+	file->driver_priv = vfile;
+
+	ret = vgem_fence_open(vfile);
+	if (ret) {
+		kfree(vfile);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
+{
+	struct vgem_file *vfile = file->driver_priv;
+
+	vgem_fence_close(vfile);
+	kfree(vfile);
+}
+
 /* ioctls */
 
 static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
@@ -134,57 +119,43 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
 					      unsigned long size)
 {
 	struct drm_vgem_gem_object *obj;
-	struct drm_gem_object *gem_object;
-	int err;
-
-	size = roundup(size, PAGE_SIZE);
+	int ret;
 
 	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 	if (!obj)
 		return ERR_PTR(-ENOMEM);
 
-	gem_object = &obj->base;
-
-	err = drm_gem_object_init(dev, gem_object, size);
-	if (err)
-		goto out;
-
-	err = vgem_gem_get_pages(obj);
-	if (err)
-		goto out;
-
-	err = drm_gem_handle_create(file, gem_object, handle);
-	if (err)
-		goto handle_out;
+	ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
+	if (ret)
+		goto err_free;
 
-	drm_gem_object_unreference_unlocked(gem_object);
+	ret = drm_gem_handle_create(file, &obj->base, handle);
+	drm_gem_object_unreference_unlocked(&obj->base);
+	if (ret)
+		goto err;
 
-	return gem_object;
+	return &obj->base;
 
-handle_out:
-	drm_gem_object_release(gem_object);
-out:
+err_free:
 	kfree(obj);
-	return ERR_PTR(err);
+err:
+	return ERR_PTR(ret);
 }
 
 static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 				struct drm_mode_create_dumb *args)
 {
 	struct drm_gem_object *gem_object;
-	uint64_t size;
-	uint64_t pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
+	u64 pitch, size;
 
+	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
 	size = args->height * pitch;
 	if (size == 0)
 		return -EINVAL;
 
 	gem_object = vgem_gem_create(dev, file, &args->handle, size);
-
-	if (IS_ERR(gem_object)) {
-		DRM_DEBUG_DRIVER("object creation failed\n");
+	if (IS_ERR(gem_object))
 		return PTR_ERR(gem_object);
-	}
 
 	args->size = gem_object->size;
 	args->pitch = pitch;
@@ -194,26 +165,26 @@ static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 	return 0;
 }
 
-int vgem_gem_dumb_map(struct drm_file *file, struct drm_device *dev,
-		      uint32_t handle, uint64_t *offset)
+static int vgem_gem_dumb_map(struct drm_file *file, struct drm_device *dev,
+			     uint32_t handle, uint64_t *offset)
 {
-	int ret = 0;
 	struct drm_gem_object *obj;
+	int ret;
 
 	obj = drm_gem_object_lookup(file, handle);
 	if (!obj)
 		return -ENOENT;
 
+	if (!obj->filp) {
+		ret = -EINVAL;
+		goto unref;
+	}
+
 	ret = drm_gem_create_mmap_offset(obj);
 	if (ret)
 		goto unref;
 
-	BUG_ON(!obj->filp);
-
-	obj->filp->private_data = obj;
-
 	*offset = drm_vma_node_offset_addr(&obj->vma_node);
-
 unref:
 	drm_gem_object_unreference_unlocked(obj);
 
@@ -221,26 +192,134 @@ unref:
 }
 
 static struct drm_ioctl_desc vgem_ioctls[] = {
+	DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
 };
 
+static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	unsigned long flags = vma->vm_flags;
+	int ret;
+
+	ret = drm_gem_mmap(filp, vma);
+	if (ret)
+		return ret;
+
+	/* Keep the WC mmaping set by drm_gem_mmap() but our pages
+	 * are ordinary and not special.
+	 */
+	vma->vm_flags = flags | VM_DONTEXPAND | VM_DONTDUMP;
+	return 0;
+}
+
 static const struct file_operations vgem_driver_fops = {
 	.owner		= THIS_MODULE,
 	.open		= drm_open,
-	.mmap		= drm_gem_mmap,
+	.mmap		= vgem_mmap,
 	.poll		= drm_poll,
 	.read		= drm_read,
 	.unlocked_ioctl = drm_ioctl,
 	.release	= drm_release,
 };
 
+static int vgem_prime_pin(struct drm_gem_object *obj)
+{
+	long n_pages = obj->size >> PAGE_SHIFT;
+	struct page **pages;
+
+	/* Flush the object from the CPU cache so that importers can rely
+	 * on coherent indirect access via the exported dma-address.
+	 */
+	pages = drm_gem_get_pages(obj);
+	if (IS_ERR(pages))
+		return PTR_ERR(pages);
+
+	drm_clflush_pages(pages, n_pages);
+	drm_gem_put_pages(obj, pages, true, false);
+
+	return 0;
+}
+
+static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj)
+{
+	struct sg_table *st;
+	struct page **pages;
+
+	pages = drm_gem_get_pages(obj);
+	if (IS_ERR(pages))
+		return ERR_CAST(pages);
+
+	st = drm_prime_pages_to_sg(pages, obj->size >> PAGE_SHIFT);
+	drm_gem_put_pages(obj, pages, false, false);
+
+	return st;
+}
+
+static void *vgem_prime_vmap(struct drm_gem_object *obj)
+{
+	long n_pages = obj->size >> PAGE_SHIFT;
+	struct page **pages;
+	void *addr;
+
+	pages = drm_gem_get_pages(obj);
+	if (IS_ERR(pages))
+		return NULL;
+
+	addr = vmap(pages, n_pages, 0, pgprot_writecombine(PAGE_KERNEL));
+	drm_gem_put_pages(obj, pages, false, false);
+
+	return addr;
+}
+
+static void vgem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
+{
+	vunmap(vaddr);
+}
+
+static int vgem_prime_mmap(struct drm_gem_object *obj,
+			   struct vm_area_struct *vma)
+{
+	int ret;
+
+	if (obj->size < vma->vm_end - vma->vm_start)
+		return -EINVAL;
+
+	if (!obj->filp)
+		return -ENODEV;
+
+	ret = obj->filp->f_op->mmap(obj->filp, vma);
+	if (ret)
+		return ret;
+
+	fput(vma->vm_file);
+	vma->vm_file = get_file(obj->filp);
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+
+	return 0;
+}
+
 static struct drm_driver vgem_driver = {
-	.driver_features		= DRIVER_GEM,
-	.gem_free_object		= vgem_gem_free_object,
+	.driver_features		= DRIVER_GEM | DRIVER_PRIME,
+	.open				= vgem_open,
+	.preclose			= vgem_preclose,
+	.gem_free_object_unlocked	= vgem_gem_free_object,
 	.gem_vm_ops			= &vgem_gem_vm_ops,
 	.ioctls				= vgem_ioctls,
+	.num_ioctls 			= ARRAY_SIZE(vgem_ioctls),
 	.fops				= &vgem_driver_fops,
+
 	.dumb_create			= vgem_gem_dumb_create,
 	.dumb_map_offset		= vgem_gem_dumb_map,
+
+	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
+	.gem_prime_pin = vgem_prime_pin,
+	.gem_prime_export = drm_gem_prime_export,
+	.gem_prime_get_sg_table = vgem_prime_get_sg_table,
+	.gem_prime_vmap = vgem_prime_vmap,
+	.gem_prime_vunmap = vgem_prime_vunmap,
+	.gem_prime_mmap = vgem_prime_mmap,
+
 	.name	= DRIVER_NAME,
 	.desc	= DRIVER_DESC,
 	.date	= DRIVER_DATE,
@@ -248,7 +327,7 @@ static struct drm_driver vgem_driver = {
 	.minor	= DRIVER_MINOR,
 };
 
-struct drm_device *vgem_device;
+static struct drm_device *vgem_device;
 
 static int __init vgem_init(void)
 {
@@ -260,10 +339,7 @@ static int __init vgem_init(void)
 		goto out;
 	}
 
-	drm_dev_set_unique(vgem_device, "vgem");
-
 	ret  = drm_dev_register(vgem_device, 0);
-
 	if (ret)
 		goto out_unref;
 
@@ -285,5 +361,6 @@ module_init(vgem_init);
 module_exit(vgem_exit);
 
 MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION(DRIVER_DESC);
 MODULE_LICENSE("GPL and additional rights");
diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
index e9f92f7ee..1f8798ad3 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.h
+++ b/drivers/gpu/drm/vgem/vgem_drv.h
@@ -32,15 +32,25 @@
 #include <drm/drmP.h>
 #include <drm/drm_gem.h>
 
+#include <uapi/drm/vgem_drm.h>
+
+struct vgem_file {
+	struct idr fence_idr;
+	struct mutex fence_mutex;
+};
+
 #define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
 struct drm_vgem_gem_object {
 	struct drm_gem_object base;
-	struct page **pages;
-	bool use_dma_buf;
 };
 
-/* vgem_drv.c */
-extern void vgem_gem_put_pages(struct drm_vgem_gem_object *obj);
-extern int vgem_gem_get_pages(struct drm_vgem_gem_object *obj);
+int vgem_fence_open(struct vgem_file *file);
+int vgem_fence_attach_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file);
+int vgem_fence_signal_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file);
+void vgem_fence_close(struct vgem_file *file);
 
 #endif
diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
new file mode 100644
index 000000000..5c57c1ffa
--- /dev/null
+++ b/drivers/gpu/drm/vgem/vgem_fence.c
@@ -0,0 +1,283 @@
+/*
+ * Copyright 2016 Intel Corporation
+ *
+ * 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
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, and/or sell copies of the Software, and to permit persons to whom
+ * them 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 MERCHANTIBILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS 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/dma-buf.h>
+#include <linux/reservation.h>
+
+#include "vgem_drv.h"
+
+#define VGEM_FENCE_TIMEOUT (10*HZ)
+
+struct vgem_fence {
+	struct fence base;
+	struct spinlock lock;
+	struct timer_list timer;
+};
+
+static const char *vgem_fence_get_driver_name(struct fence *fence)
+{
+	return "vgem";
+}
+
+static const char *vgem_fence_get_timeline_name(struct fence *fence)
+{
+	return "unbound";
+}
+
+static bool vgem_fence_signaled(struct fence *fence)
+{
+	return false;
+}
+
+static bool vgem_fence_enable_signaling(struct fence *fence)
+{
+	return true;
+}
+
+static void vgem_fence_release(struct fence *base)
+{
+	struct vgem_fence *fence = container_of(base, typeof(*fence), base);
+
+	del_timer_sync(&fence->timer);
+	fence_free(&fence->base);
+}
+
+static void vgem_fence_value_str(struct fence *fence, char *str, int size)
+{
+	snprintf(str, size, "%u", fence->seqno);
+}
+
+static void vgem_fence_timeline_value_str(struct fence *fence, char *str,
+					  int size)
+{
+	snprintf(str, size, "%u", fence_is_signaled(fence) ? fence->seqno : 0);
+}
+
+static const struct fence_ops vgem_fence_ops = {
+	.get_driver_name = vgem_fence_get_driver_name,
+	.get_timeline_name = vgem_fence_get_timeline_name,
+	.enable_signaling = vgem_fence_enable_signaling,
+	.signaled = vgem_fence_signaled,
+	.wait = fence_default_wait,
+	.release = vgem_fence_release,
+
+	.fence_value_str = vgem_fence_value_str,
+	.timeline_value_str = vgem_fence_timeline_value_str,
+};
+
+static void vgem_fence_timeout(unsigned long data)
+{
+	struct vgem_fence *fence = (struct vgem_fence *)data;
+
+	fence_signal(&fence->base);
+}
+
+static struct fence *vgem_fence_create(struct vgem_file *vfile,
+				       unsigned int flags)
+{
+	struct vgem_fence *fence;
+
+	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+	if (!fence)
+		return NULL;
+
+	spin_lock_init(&fence->lock);
+	fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
+		   fence_context_alloc(1), 1);
+
+	setup_timer(&fence->timer, vgem_fence_timeout, (unsigned long)fence);
+
+	/* We force the fence to expire within 10s to prevent driver hangs */
+	mod_timer(&fence->timer, jiffies + VGEM_FENCE_TIMEOUT);
+
+	return &fence->base;
+}
+
+static int attach_dmabuf(struct drm_device *dev,
+			 struct drm_gem_object *obj)
+{
+	struct dma_buf *dmabuf;
+
+	if (obj->dma_buf)
+		return 0;
+
+	dmabuf = dev->driver->gem_prime_export(dev, obj, 0);
+	if (IS_ERR(dmabuf))
+		return PTR_ERR(dmabuf);
+
+	obj->dma_buf = dmabuf;
+	drm_gem_object_reference(obj);
+	return 0;
+}
+
+/*
+ * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH):
+ *
+ * Create and attach a fence to the vGEM handle. This fence is then exposed
+ * via the dma-buf reservation object and visible to consumers of the exported
+ * dma-buf. If the flags contain VGEM_FENCE_WRITE, the fence indicates the
+ * vGEM buffer is being written to by the client and is exposed as an exclusive
+ * fence, otherwise the fence indicates the client is current reading from the
+ * buffer and all future writes should wait for the client to signal its
+ * completion. Note that if a conflicting fence is already on the dma-buf (i.e.
+ * an exclusive fence when adding a read, or any fence when adding a write),
+ * -EBUSY is reported. Serialisation between operations should be handled
+ * by waiting upon the dma-buf.
+ *
+ * This returns the handle for the new fence that must be signaled within 10
+ * seconds (or otherwise it will automatically expire). See
+ * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL).
+ *
+ * If the vGEM handle does not exist, vgem_fence_attach_ioctl returns -ENOENT.
+ */
+int vgem_fence_attach_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file)
+{
+	struct drm_vgem_fence_attach *arg = data;
+	struct vgem_file *vfile = file->driver_priv;
+	struct reservation_object *resv;
+	struct drm_gem_object *obj;
+	struct fence *fence;
+	int ret;
+
+	if (arg->flags & ~VGEM_FENCE_WRITE)
+		return -EINVAL;
+
+	if (arg->pad)
+		return -EINVAL;
+
+	obj = drm_gem_object_lookup(file, arg->handle);
+	if (!obj)
+		return -ENOENT;
+
+	ret = attach_dmabuf(dev, obj);
+	if (ret)
+		goto err;
+
+	fence = vgem_fence_create(vfile, arg->flags);
+	if (!fence) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	/* Check for a conflicting fence */
+	resv = obj->dma_buf->resv;
+	if (!reservation_object_test_signaled_rcu(resv,
+						  arg->flags & VGEM_FENCE_WRITE)) {
+		ret = -EBUSY;
+		goto err_fence;
+	}
+
+	/* Expose the fence via the dma-buf */
+	ret = 0;
+	mutex_lock(&resv->lock.base);
+	if (arg->flags & VGEM_FENCE_WRITE)
+		reservation_object_add_excl_fence(resv, fence);
+	else if ((ret = reservation_object_reserve_shared(resv)) == 0)
+		reservation_object_add_shared_fence(resv, fence);
+	mutex_unlock(&resv->lock.base);
+
+	/* Record the fence in our idr for later signaling */
+	if (ret == 0) {
+		mutex_lock(&vfile->fence_mutex);
+		ret = idr_alloc(&vfile->fence_idr, fence, 1, 0, GFP_KERNEL);
+		mutex_unlock(&vfile->fence_mutex);
+		if (ret > 0) {
+			arg->out_fence = ret;
+			ret = 0;
+		}
+	}
+err_fence:
+	if (ret) {
+		fence_signal(fence);
+		fence_put(fence);
+	}
+err:
+	drm_gem_object_unreference_unlocked(obj);
+	return ret;
+}
+
+/*
+ * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL):
+ *
+ * Signal and consume a fence ealier attached to a vGEM handle using
+ * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH).
+ *
+ * All fences must be signaled within 10s of attachment or otherwise they
+ * will automatically expire (and a vgem_fence_signal_ioctl returns -ETIMEDOUT).
+ *
+ * Signaling a fence indicates to all consumers of the dma-buf that the
+ * client has completed the operation associated with the fence, and that the
+ * buffer is then ready for consumption.
+ *
+ * If the fence does not exist (or has already been signaled by the client),
+ * vgem_fence_signal_ioctl returns -ENOENT.
+ */
+int vgem_fence_signal_ioctl(struct drm_device *dev,
+			    void *data,
+			    struct drm_file *file)
+{
+	struct vgem_file *vfile = file->driver_priv;
+	struct drm_vgem_fence_signal *arg = data;
+	struct fence *fence;
+	int ret = 0;
+
+	if (arg->flags)
+		return -EINVAL;
+
+	mutex_lock(&vfile->fence_mutex);
+	fence = idr_replace(&vfile->fence_idr, NULL, arg->fence);
+	mutex_unlock(&vfile->fence_mutex);
+	if (!fence)
+		return -ENOENT;
+	if (IS_ERR(fence))
+		return PTR_ERR(fence);
+
+	if (fence_is_signaled(fence))
+		ret = -ETIMEDOUT;
+
+	fence_signal(fence);
+	fence_put(fence);
+	return ret;
+}
+
+int vgem_fence_open(struct vgem_file *vfile)
+{
+	mutex_init(&vfile->fence_mutex);
+	idr_init(&vfile->fence_idr);
+
+	return 0;
+}
+
+static int __vgem_fence_idr_fini(int id, void *p, void *data)
+{
+	fence_signal(p);
+	fence_put(p);
+	return 0;
+}
+
+void vgem_fence_close(struct vgem_file *vfile)
+{
+	idr_for_each(&vfile->fence_idr, __vgem_fence_idr_fini, vfile);
+	idr_destroy(&vfile->fence_idr);
+}