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) are a 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 "drm_internal.h"
#include <drm/drm_syncobj.h>

/**
 * 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.
 */
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);
}

/**
 * drm_syncobj_add_callback - adds a callback to syncobj::cb_list
 * @syncobj: Sync object to which to add the callback
 * @cb: Callback to add
 * @func: Func to use when initializing the drm_syncobj_cb struct
 *
 * This adds a callback to be called next time the fence is replaced
 */
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);
}
EXPORT_SYMBOL(drm_syncobj_add_callback);

/**
 * drm_syncobj_add_callback - removes a callback to syncobj::cb_list
 * @syncobj: Sync object from which to remove the callback
 * @cb: Callback to remove
 */
void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
				 struct drm_syncobj_cb *cb)
{
	spin_lock(&syncobj->lock);
	list_del_init(&cb->node);
	spin_unlock(&syncobj->lock);
}
EXPORT_SYMBOL(drm_syncobj_remove_callback);

/**
 * drm_syncobj_replace_fence - replace fence in a sync object.
 * @syncobj: Sync object to replace fence in
 * @fence: fence to install in sync file.
 *
 * This replaces the fence on a sync object.
 */
void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
			       struct dma_fence *fence)
{
	struct dma_fence *old_fence;
	struct drm_syncobj_cb *cur, *tmp;

	if (fence)
		dma_fence_get(fence);

	spin_lock(&syncobj->lock);

	old_fence = syncobj->fence;
	syncobj->fence = fence;

	if (fence != old_fence) {
		list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {
			list_del_init(&cur->node);
			cur->func(syncobj, cur);
		}
	}

	spin_unlock(&syncobj->lock);

	dma_fence_put(old_fence);
}
EXPORT_SYMBOL(drm_syncobj_replace_fence);

int drm_syncobj_find_fence(struct drm_file *file_private,
			   u32 handle,
			   struct dma_fence **fence)
{
	struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
	int ret = 0;

	if (!syncobj)
		return -ENOENT;

	*fence = drm_syncobj_fence_get(syncobj);
	if (!*fence) {
		ret = -EINVAL;
	}
	drm_syncobj_put(syncobj);
	return ret;
}
EXPORT_SYMBOL(drm_syncobj_find_fence);

/**
 * drm_syncobj_free - free a sync object.
 * @kref: kref to free.
 *
 * Only to be called from kref_put in drm_syncobj_put.
 */
void drm_syncobj_free(struct kref *kref)
{
	struct drm_syncobj *syncobj = container_of(kref,
						   struct drm_syncobj,
						   refcount);
	drm_syncobj_replace_fence(syncobj, NULL);
	kfree(syncobj);
}
EXPORT_SYMBOL(drm_syncobj_free);

static int drm_syncobj_create(struct drm_file *file_private,
			      u32 *handle)
{
	int ret;
	struct drm_syncobj *syncobj;

	syncobj = kzalloc(sizeof(struct drm_syncobj), GFP_KERNEL);
	if (!syncobj)
		return -ENOMEM;

	kref_init(&syncobj->refcount);
	INIT_LIST_HEAD(&syncobj->cb_list);
	spin_lock_init(&syncobj->lock);

	idr_preload(GFP_KERNEL);
	spin_lock(&file_private->syncobj_table_lock);
	ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
	spin_unlock(&file_private->syncobj_table_lock);

	idr_preload_end();

	if (ret < 0) {
		drm_syncobj_put(syncobj);
		return ret;
	}

	*handle = ret;
	return 0;
}

static int drm_syncobj_destroy(struct drm_file *file_private,
			       u32 handle)
{
	struct drm_syncobj *syncobj;

	spin_lock(&file_private->syncobj_table_lock);
	syncobj = idr_remove(&file_private->syncobj_idr, handle);
	spin_unlock(&file_private->syncobj_table_lock);

	if (!syncobj)
		return -EINVAL;

	drm_syncobj_put(syncobj);
	return 0;
}

static int drm_syncobj_file_release(struct inode *inode, struct file *file)
{
	struct drm_syncobj *syncobj = file->private_data;

	drm_syncobj_put(syncobj);
	return 0;
}

static const struct file_operations drm_syncobj_file_fops = {
	.release = drm_syncobj_file_release,
};

static int drm_syncobj_alloc_file(struct drm_syncobj *syncobj)
{
	struct file *file = anon_inode_getfile("syncobj_file",
					       &drm_syncobj_file_fops,
					       syncobj, 0);
	if (IS_ERR(file))
		return PTR_ERR(file);

	drm_syncobj_get(syncobj);
	if (cmpxchg(&syncobj->file, NULL, file)) {
		/* lost the race */
		fput(file);
	}

	return 0;
}

static int drm_syncobj_handle_to_fd(struct drm_file *file_private,
				    u32 handle, int *p_fd)
{
	struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
	int ret;
	int fd;

	if (!syncobj)
		return -EINVAL;

	fd = get_unused_fd_flags(O_CLOEXEC);
	if (fd < 0) {
		drm_syncobj_put(syncobj);
		return fd;
	}

	if (!syncobj->file) {
		ret = drm_syncobj_alloc_file(syncobj);
		if (ret)
			goto out_put_fd;
	}
	fd_install(fd, syncobj->file);
	drm_syncobj_put(syncobj);
	*p_fd = fd;
	return 0;
out_put_fd:
	put_unused_fd(fd);
	drm_syncobj_put(syncobj);
	return ret;
}

static struct drm_syncobj *drm_syncobj_fdget(int fd)
{
	struct file *file = fget(fd);

	if (!file)
		return NULL;
	if (file->f_op != &drm_syncobj_file_fops)
		goto err;

	return file->private_data;
err:
	fput(file);
	return NULL;
};

static int drm_syncobj_fd_to_handle(struct drm_file *file_private,
				    int fd, u32 *handle)
{
	struct drm_syncobj *syncobj = drm_syncobj_fdget(fd);
	int ret;

	if (!syncobj)
		return -EINVAL;

	/* take a reference to put in the idr */
	drm_syncobj_get(syncobj);

	idr_preload(GFP_KERNEL);
	spin_lock(&file_private->syncobj_table_lock);
	ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
	spin_unlock(&file_private->syncobj_table_lock);
	idr_preload_end();

	if (ret < 0) {
		fput(syncobj->file);
		return ret;
	}
	*handle = ret;
	return 0;
}

int drm_syncobj_import_sync_file_fence(struct drm_file *file_private,
				       int fd, int handle)
{
	struct dma_fence *fence = sync_file_get_fence(fd);
	struct drm_syncobj *syncobj;

	if (!fence)
		return -EINVAL;

	syncobj = drm_syncobj_find(file_private, handle);
	if (!syncobj) {
		dma_fence_put(fence);
		return -ENOENT;
	}

	drm_syncobj_replace_fence(syncobj, fence);
	dma_fence_put(fence);
	drm_syncobj_put(syncobj);
	return 0;
}

int drm_syncobj_export_sync_file(struct drm_file *file_private,
				 int handle, int *p_fd)
{
	int ret;
	struct dma_fence *fence;
	struct sync_file *sync_file;
	int fd = get_unused_fd_flags(O_CLOEXEC);

	if (fd < 0)
		return fd;

	ret = drm_syncobj_find_fence(file_private, handle, &fence);
	if (ret)
		goto err_put_fd;

	sync_file = sync_file_create(fence);

	dma_fence_put(fence);

	if (!sync_file) {
		ret = -EINVAL;
		goto err_put_fd;
	}

	fd_install(fd, sync_file->file);

	*p_fd = fd;
	return 0;
err_put_fd:
	put_unused_fd(fd);
	return ret;
}
/**
 * drm_syncobj_open - initalizes syncobj file-private structures at devnode open time
 * @file_private: drm file-private structure to set up
 *
 * Called at device open time, sets up the structure for handling refcounting
 * of sync objects.
 */
void
drm_syncobj_open(struct drm_file *file_private)
{
	idr_init(&file_private->syncobj_idr);
	spin_lock_init(&file_private->syncobj_table_lock);
}

static int
drm_syncobj_release_handle(int id, void *ptr, void *data)
{
	struct drm_syncobj *syncobj = ptr;

	drm_syncobj_put(syncobj);
	return 0;
}

/**
 * drm_syncobj_release - release file-private sync object resources
 * @file_private: drm file-private structure to clean up
 *
 * Called at close time when the filp is going away.
 *
 * Releases any remaining references on objects by this filp.
 */
void
drm_syncobj_release(struct drm_file *file_private)
{
	idr_for_each(&file_private->syncobj_idr,
		     &drm_syncobj_release_handle, file_private);
	idr_destroy(&file_private->syncobj_idr);
}

int
drm_syncobj_create_ioctl(struct drm_device *dev, void *data,
			 struct drm_file *file_private)
{
	struct drm_syncobj_create *args = data;

	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
		return -ENODEV;

	/* no valid flags yet */
	if (args->flags)
		return -EINVAL;

	return drm_syncobj_create(file_private,
				  &args->handle);
}

int
drm_syncobj_destroy_ioctl(struct drm_device *dev, void *data,
			  struct drm_file *file_private)
{
	struct drm_syncobj_destroy *args = data;

	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
		return -ENODEV;

	/* make sure padding is empty */
	if (args->pad)
		return -EINVAL;
	return drm_syncobj_destroy(file_private, args->handle);
}

int
drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
				   struct drm_file *file_private)
{
	struct drm_syncobj_handle *args = data;

	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
		return -ENODEV;

	if (args->pad)
		return -EINVAL;

	if (args->flags != 0 &&
	    args->flags != DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
		return -EINVAL;

	if (args->flags & DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
		return drm_syncobj_export_sync_file(file_private, args->handle,
						    &args->fd);

	return drm_syncobj_handle_to_fd(file_private, args->handle,
					&args->fd);
}

int
drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
				   struct drm_file *file_private)
{
	struct drm_syncobj_handle *args = data;

	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
		return -ENODEV;

	if (args->pad)
		return -EINVAL;

	if (args->flags != 0 &&
	    args->flags != DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE)
		return -EINVAL;

	if (args->flags & DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE)
		return drm_syncobj_import_sync_file_fence(file_private,
							  args->fd,
							  args->handle);

	return drm_syncobj_fd_to_handle(file_private, args->fd,
					&args->handle);
}

/**
 * drm_timeout_abs_to_jiffies - calculate jiffies timeout from absolute value
 *
 * @timeout_nsec: timeout nsec component in ns, 0 for poll
 *
 * Calculate the timeout in jiffies from an absolute time in sec/nsec.
 */
static signed long drm_timeout_abs_to_jiffies(int64_t timeout_nsec)
{
	ktime_t abs_timeout, now;
	u64 timeout_ns, timeout_jiffies64;

	/* make 0 timeout means poll - absolute 0 doesn't seem valid */
	if (timeout_nsec == 0)
		return 0;

	abs_timeout = ns_to_ktime(timeout_nsec);
	now = ktime_get();

	if (!ktime_after(abs_timeout, now))
		return 0;

	timeout_ns = ktime_to_ns(ktime_sub(abs_timeout, now));

	timeout_jiffies64 = nsecs_to_jiffies64(timeout_ns);
	/*  clamp timeout to avoid infinite timeout */
	if (timeout_jiffies64 >= MAX_SCHEDULE_TIMEOUT - 1)
		return MAX_SCHEDULE_TIMEOUT - 1;

	return timeout_jiffies64 + 1;
}

static int drm_syncobj_wait_fences(struct drm_device *dev,
				   struct drm_file *file_private,
				   struct drm_syncobj_wait *wait,
				   struct dma_fence **fences)
{
	signed long timeout = drm_timeout_abs_to_jiffies(wait->timeout_nsec);
	signed long ret = 0;
	uint32_t first = ~0;

	if (wait->flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL) {
		uint32_t i;
		for (i = 0; i < wait->count_handles; i++) {
			ret = dma_fence_wait_timeout(fences[i], true, timeout);

			/* Various dma_fence wait callbacks will return
			 * ENOENT to indicate that the fence has already
			 * been signaled.  We need to sanitize this to 0 so
			 * we don't return early and the client doesn't see
			 * an unexpected error.
			 */
			if (ret == -ENOENT)
				ret = 0;

			if (ret < 0)
				return ret;
			if (ret == 0)
				break;
			timeout = ret;
		}
		first = 0;
	} else {
		ret = dma_fence_wait_any_timeout(fences,
						 wait->count_handles,
						 true, timeout,
						 &first);
	}

	if (ret < 0)
		return ret;

	wait->first_signaled = first;
	if (ret == 0)
		return -ETIME;
	return 0;
}

int
drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
		       struct drm_file *file_private)
{
	struct drm_syncobj_wait *args = data;
	uint32_t *handles;
	struct dma_fence **fences;
	int ret = 0;
	uint32_t i;

	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
		return -ENODEV;

	if (args->flags != 0 && args->flags != DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL)
		return -EINVAL;

	if (args->count_handles == 0)
		return -EINVAL;

	/* Get the handles from userspace */
	handles = kmalloc_array(args->count_handles, sizeof(uint32_t),
				GFP_KERNEL);
	if (handles == NULL)
		return -ENOMEM;

	if (copy_from_user(handles,
			   u64_to_user_ptr(args->handles),
			   sizeof(uint32_t) * args->count_handles)) {
		ret = -EFAULT;
		goto err_free_handles;
	}

	fences = kcalloc(args->count_handles,
			 sizeof(struct dma_fence *), GFP_KERNEL);
	if (!fences) {
		ret = -ENOMEM;
		goto err_free_handles;
	}

	for (i = 0; i < args->count_handles; i++) {
		ret = drm_syncobj_find_fence(file_private, handles[i],
					     &fences[i]);
		if (ret)
			goto err_free_fence_array;
	}

	ret = drm_syncobj_wait_fences(dev, file_private,
				      args, fences);

err_free_fence_array:
	for (i = 0; i < args->count_handles; i++)
		dma_fence_put(fences[i]);
	kfree(fences);
err_free_handles:
	kfree(handles);

	return ret;
}