path: root/drivers/gpu/drm/drm_syncobj.c

/*
 * Copyright 2017 Red Hat
 * Parts ported from amdgpu (fence wait code).
 * Copyright 2016 Advanced Micro Devices, Inc.
 *
 * 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
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 *
 * Authors:
 *
 */

/**
 * DOC: Overview
 *
 * DRM synchronisation objects (syncobj, see struct &drm_syncobj) are
 * persistent objects that contain an optional fence. The fence can be updated
 * with a new fence, or be NULL.
 *
 * syncobj's can be waited upon, where it will wait for the underlying
 * fence.
 *
 * syncobj's can be export to fd's and back, these fd's are opaque and
 * have no other use case, except passing the syncobj between processes.
 *
 * Their primary use-case is to implement Vulkan fences and semaphores.
 *
 * syncobj have a kref reference count, but also have an optional file.
 * The file is only created once the syncobj is exported.
 * The file takes a reference on the kref.
 */

#include <drm/drmP.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/anon_inodes.h>
#include <linux/sync_file.h>
#include <linux/sched/signal.h>

#include "drm_internal.h"
#include <drm/drm_syncobj.h>

/* merge normal syncobj to timeline syncobj, the point interval is 1 */
#define DRM_SYNCOBJ_BINARY_POINT 1

struct drm_syncobj_stub_fence {
	struct dma_fence base;
	spinlock_t lock;
};

static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
{
        return "syncobjstub";
}

static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
	.get_driver_name = drm_syncobj_stub_fence_get_name,
	.get_timeline_name = drm_syncobj_stub_fence_get_name,
};

struct drm_syncobj_signal_pt {
	struct dma_fence_array *fence_array;
	u64    value;
	struct list_head list;
};

/**
 * drm_syncobj_find - lookup and reference a sync object.
 * @file_private: drm file private pointer
 * @handle: sync object handle to lookup.
 *
 * Returns a reference to the syncobj pointed to by handle or NULL. The
 * reference must be released by calling drm_syncobj_put().
 */
struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
				     u32 handle)
{
	struct drm_syncobj *syncobj;

	spin_lock(&file_private->syncobj_table_lock);

	/* Check if we currently have a reference on the object */
	syncobj = idr_find(&file_private->syncobj_idr, handle);
	if (syncobj)
		drm_syncobj_get(syncobj);

	spin_unlock(&file_private->syncobj_table_lock);

	return syncobj;
}
EXPORT_SYMBOL(drm_syncobj_find);

static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
					    struct drm_syncobj_cb *cb,
					    drm_syncobj_func_t func)
{
	cb->func = func;
	list_add_tail(&cb->node, &syncobj->cb_list);
}

static int drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
						 struct dma_fence **fence,
						 struct drm_syncobj_cb *cb,
						 drm_syncobj_func_t func)
{
	int ret;

	ret = drm_syncobj_search_fence(syncobj, 0, 0, fence);
	if (!ret)
		return 1;

	spin_lock(&syncobj->lock);
	/* We've already tried once to get a fence and failed.  Now that we
	 * have the lock, try one more time just to be sure we don't add a
	 * callback when a fence has already been set.
	 */
	if (!list_empty(&syncobj->signal_pt_list)) {
		spin_unlock(&syncobj->lock);
		drm_syncobj_search_fence(syncobj, 0, 0, fence);
		if (*fence)
			return 1;
		spin_lock(&syncobj->lock);
	} else {
		*fence = NULL;
		drm_syncobj_add_callback_locked(syncobj, cb, func);
		ret = 0;
	}
	spin_unlock(&syncobj->lock);

	return ret;
}

void drm_syncobj_add_callback(struct drm_syncobj *syncobj,
			      struct drm_syncobj_cb *cb,
			      drm_syncobj_func_t func)
{
	spin_lock(&syncobj->lock);
	drm_syncobj_add_callback_locked(syncobj, cb, func);
	spin_unlock(&syncobj->lock);
}

void drm_syncobj_remove_callback(