drm sync objects (search for spock)

From: Dave Airlie <[email protected]>

Sync objects are new toplevel drm object, that contain a pointer to a fence. This fence can be updated via command submission ioctls via drivers.

There is also a generic wait obj API modelled on the vulkan wait API (with code modelled on some amdgpu code).

These objects can be converted to an opaque fd that can be passes between processes.

TODO: define sync_file interaction.

Signed-off-by Dave Airlie <[email protected]>

---
  Documentation/gpu/drm-internals.rst |   3 +
  Documentation/gpu/drm-mm.rst        |   6 +
  drivers/gpu/drm/Makefile            |   2 +-
  drivers/gpu/drm/drm_fops.c          |   8 +
  drivers/gpu/drm/drm_internal.h      |  13 ++
  drivers/gpu/drm/drm_ioctl.c         |  12 ++
  drivers/gpu/drm/drm_syncobj.c       | 374 ++++++++++++++++++++++++++++++++++++
  include/drm/drmP.h                  |   5 +
  include/drm/drm_drv.h               |   1 +
  include/drm/drm_syncobj.h           | 104 ++++++++++
  include/uapi/drm/drm.h              |  25 +++
  11 files changed, 552 insertions(+), 1 deletion(-)

create mode 100644 drivers/gpu/drm/drm_syncobj.c create mode 100644 include/drm/drm_syncobj.h

Documentation/gpu/drm-internals.rst +3 -0

index e35920d..2ea3bce 100644
@@ -98,6 +98,9 @@ DRIVER_ATOMIC
      implement appropriate obj->atomic_get_property() vfuncs for any
      modeset objects with driver specific properties.
 
+DRIVER_SYNCOBJ
+    Driver support drm sync objects.
+
  Major, Minor and Patchlevel
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

Documentation/gpu/drm-mm.rst +6 -0

index f5760b1..28aebe8 100644
@@ -483,3 +483,9 @@ DRM Cache Handling
 
  .. kernel-doc:: drivers/gpu/drm/drm_cache.c
     :export:
+
+DRM Sync Objects
+===========================
+
+.. kernel-doc:: drivers/gpu/drm/drm_syncobj.c
+   :export:

drivers/gpu/drm/Makefile +1 -1

index 3ee9579..b5e565c 100644
@@ -16,7 +16,7 @@ drm-y       :=	drm_auth.o drm_bufs.o drm_cache.o \
  		drm_framebuffer.o drm_connector.o drm_blend.o \
  		drm_encoder.o drm_mode_object.o drm_property.o \
  		drm_plane.o drm_color_mgmt.o drm_print.o \
-		drm_dumb_buffers.o drm_mode_config.o
+		drm_dumb_buffers.o drm_mode_config.o drm_syncobj.o
 
  drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o
  drm-$(CONFIG_DRM_VM) += drm_vm.o

drivers/gpu/drm/drm_fops.c +8 -0

index afdf5b1..9a61df2 100644
@@ -219,6 +219,9 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
  	if (drm_core_check_feature(dev, DRIVER_GEM))
  		drm_gem_open(dev, priv);
 
+	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
+		drm_syncobj_open(priv);
+
  	if (drm_core_check_feature(dev, DRIVER_PRIME))
  		drm_prime_init_file_private(&priv->prime);
 

@@ -266,6 +269,8 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
  out_prime_destroy:
  	if (drm_core_check_feature(dev, DRIVER_PRIME))
  		drm_prime_destroy_file_private(&priv->prime);
+	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
+		drm_syncobj_release(priv);
  	if (drm_core_check_feature(dev, DRIVER_GEM))
  		drm_gem_release(dev, priv);
  	put_pid(priv->pid);

@@ -400,6 +405,9 @@ int drm_release(struct inode *inode, struct file *filp)
  		drm_property_destroy_user_blobs(dev, file_priv);
  	}
 
+	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
+		drm_syncobj_release(file_priv);
+
  	if (drm_core_check_feature(dev, DRIVER_GEM))
  		drm_gem_release(dev, file_priv);
 

drivers/gpu/drm/drm_internal.h +13 -0

index f37388c..44ef903 100644
@@ -142,4 +142,17 @@ static inline int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
  {
  	return 0;
  }
+
  #endif
+
+/* drm_syncobj.c */
+void drm_syncobj_open(struct drm_file *file_private);
+void drm_syncobj_release(struct drm_file *file_private);
+int drm_syncobj_create_ioctl(struct drm_device *dev, void *data,
+			     struct drm_file *file_private);
+int drm_syncobj_destroy_ioctl(struct drm_device *dev, void *data,
+			      struct drm_file *file_private);
+int drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
+				   struct drm_file *file_private);
+int drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
+				   struct drm_file *file_private);

drivers/gpu/drm/drm_ioctl.c +12 -0

index a7c61c2..6da7adc 100644
@@ -240,6 +240,9 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
  		req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0;
  		req->value |= dev->driver->prime_handle_to_fd ? DRM_PRIME_CAP_EXPORT : 0;
  		return 0;
+	case DRM_CAP_SYNCOBJ:
+		req->value = drm_core_check_feature(dev, DRIVER_SYNCOBJ);
+		return 0;
  	}
 
  	/* Other caps only work with KMS drivers */

@@ -641,6 +644,15 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_ATOMIC, drm_mode_atomic_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATEPROPBLOB, drm_mode_createblob_ioctl, DRM_CONTROL_ALLOW|DRM_UNLOCKED),
  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_DESTROYPROPBLOB, drm_mode_destroyblob_ioctl, DRM_CONTROL_ALLOW|DRM_UNLOCKED),
+
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_CREATE, drm_syncobj_create_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_DESTROY, drm_syncobj_destroy_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD, drm_syncobj_handle_to_fd_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE, drm_syncobj_fd_to_handle_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
  };
 
  #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE( drm_ioctls )

drivers/gpu/drm/drm_syncobj.c new file +116 -0

new file mode 100644
index 0000000..e6a99d4
@@ -0,0 +1,374 @@
+/*
+ * Copyright 2017 Red Hat
+ *
+ * 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 export to fd's and back, these fd's are opaque and
+ * have no other use case, except passing the syncobj between processes.
+ *
+ * TODO: sync_file interactions, waiting
+ *
+ * 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 "drm_internal.h"
+#include <drm/drm_syncobj.h>
+
+static struct drm_syncobj *drm_syncobj_get(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_reference(syncobj);
+
+	spin_unlock(&file_private->syncobj_table_lock);
+
+	return syncobj;
+}
+
+/**
+ * drm_syncobj_replace_fence - lookup and replace fence in a sync object.
+ * @file_private - drm file private pointer.
+ * @handle - syncobj handle to lookup
+ * @fence - fence to install in sync file.
+ * Returns:
+ * 0 on success, or -EINVAL when the handle doesn't point at a valid sem file.
+ *
+ * This looks up a sync object and replaces the fence on it, freeing
+ * the old one.
+ */
+int drm_syncobj_replace_fence(struct drm_file *file_private,
+			      u32 handle,
+			      struct dma_fence *fence)
+{
+	struct drm_syncobj *syncobj = drm_syncobj_get(file_private, handle);
+	struct dma_fence *old_fence = NULL;
+
+	if (!syncobj)
+		return -EINVAL;
+
+	if (fence)
+		dma_fence_get(fence);
+	old_fence = xchg(&syncobj->fence, fence);
+
+	dma_fence_put(old_fence);
+	drm_syncobj_unreference(syncobj);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_syncobj_replace_fence);
+
+int drm_syncobj_fence_get(struct drm_file *file_private,
+			  u32 handle,
+			  struct dma_fence **fence)
+{
+	struct drm_syncobj *syncobj = drm_syncobj_get(file_private, handle);
+	int ret = 0;
+
+	if (!syncobj)
+		return -EINVAL;
+
+	*fence = dma_fence_get(syncobj->fence);
+	if (!*fence) {
+		ret = -EINVAL;
+	}

drivers/gpu/drm/drm_syncobj.c new file +248 -0

+	kfree(syncobj);
+}
+
+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;
+
+	mutex_init(&syncobj->file_lock);
+	kref_init(&syncobj->refcount);
+
+	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_unreference(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_unreference(syncobj);
+	return 0;
+}
+
+static int drm_syncobj_file_release(struct inode *inode, struct file *file)
+{
+	struct drm_syncobj *syncobj = file->private_data;
+
+	drm_syncobj_unreference(syncobj);
+	return 0;
+}
+
+static const struct file_operations drm_syncobj_file_fops = {
+	.release = drm_syncobj_file_release,
+};
+
+static int drm_syncobj_alloc_file_locked(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);
+
+	/* the file holds a reference to the object */
+	drm_syncobj_reference(syncobj);
+	syncobj->file = 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_get(file_private, handle);
+	int ret;
+	int fd;
+
+	if (!syncobj)
+		return -EINVAL;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0) {
+		drm_syncobj_unreference(syncobj);
+		return fd;
+	}
+
+	mutex_lock(&syncobj->file_lock);
+	if (!syncobj->file) {
+		ret = drm_syncobj_alloc_file_locked(syncobj);
+		if (ret)
+			goto out_unlock;
+	}
+	fd_install(fd, syncobj->file);
+	mutex_unlock(&syncobj->file_lock);
+	drm_syncobj_unreference(syncobj);
+	*p_fd = fd;
+	return 0;
+out_unlock:
+	put_unused_fd(fd);
+	mutex_unlock(&syncobj->file_lock);
+	drm_syncobj_unreference(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_reference(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;
+}
+
+/**
+ * drm_syncobj_open - initalizes syncobj file-private structures at devnode open time
+ * @dev: drm_device which is being opened by userspace
+ * @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_unreference(syncobj);
+	return 0;
+}
+
+/**
+ * drm_syncobj_release - release file-private sync object resources
+ * @dev: drm_device which is being closed by userspace
+ * @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;
+
+	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;
+
+	return drm_syncobj_fd_to_handle(file_private, args->fd,
+					&args->handle);
+}

include/drm/drmP.h +5 -0

index 6105c05..1d48f6f 100644
@@ -405,6 +405,11 @@ struct drm_file {
  	/** Lock for synchronization of access to object_idr. */
  	spinlock_t table_lock;
 
+	/** Mapping of sync object handles to object pointers. */
+	struct idr syncobj_idr;
+	/** Lock for synchronization of access to syncobj_idr. */
+	spinlock_t syncobj_table_lock;
+
  	struct file *filp;
  	void *driver_priv;
 

include/drm/drm_drv.h +1 -0

index 5699f42..48ff06b 100644
@@ -53,6 +53,7 @@ struct drm_mode_create_dumb;
  #define DRIVER_RENDER			0x8000
  #define DRIVER_ATOMIC			0x10000
  #define DRIVER_KMS_LEGACY_CONTEXT	0x20000
+#define DRIVER_SYNCOBJ                  0x40000
 
  /**
   * struct drm_driver - DRM driver structure

include/drm/drm_syncobj.h new file +104 -0

new file mode 100644
index 0000000..3cc42b7
@@ -0,0 +1,104 @@
+/*
+ * Copyright © 2017 Red Hat
+ *
+ * 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:
+ *
+ */
+#ifndef __DRM_SYNCOBJ_H__
+#define __DRM_SYNCOBJ_H__
+
+#include "linux/dma-fence.h"
+
+/**
+ * struct drm_syncobj - sync object.
+ *
+ * This structure defines a generic sync object which wraps a dma fence.
+ */
+struct drm_syncobj {
+	/**
+	 * @refcount:
+	 *
+	 * Reference count of this object.
+	 */
+	struct kref refcount;
+	/**
+	 * @fence:
+	 * NULL or a pointer to the fence bound to this object.
+	 */
+	struct dma_fence *fence;
+	/**
+	 * @file_lock
+	 * mutex protecting the struct file pointer.
+	 */
+	struct mutex file_lock;
+	/**
+	 * @file
+	 * a file backing for this syncobj.
+	 */
+	struct file *file;
+};
+
+void drm_syncobj_free(struct kref *kref);
+
+/**
+ * drm_gem_object_reference - acquire a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This acquires additional reference to @obj. It is illegal to call this
+ * without already holding a reference. No locks required.
+ */
+static inline void
+drm_syncobj_reference(struct drm_syncobj *obj)
+{
+	kref_get(&obj->refcount);
+}
+
+/**
+ * __drm_gem_object_unreference - raw function to release a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This function is meant to be used by drivers which are not encumbered with
+ * &drm_device.struct_mutex legacy locking and which are using the
+ * gem_free_object_unlocked callback. It avoids all the locking checks and
+ * locking overhead of drm_gem_object_unreference() and
+ * drm_gem_object_unreference_unlocked().
+ *
+ * Drivers should never call this directly in their code. Instead they should
+ * wrap it up into a ``driver_gem_object_unreference(struct driver_gem_object
+ * *obj)`` wrapper function, and use that. Shared code should never call this, to
+ * avoid breaking drivers by accident which still depend upon
+ * &drm_device.struct_mutex locking.
+ */
+static inline void
+drm_syncobj_unreference(struct drm_syncobj *obj)
+{
+	kref_put(&obj->refcount, drm_syncobj_free);
+}
+
+int drm_syncobj_fence_get(struct drm_file *file_private,
+			  u32 handle,
+			  struct dma_fence **fence);
+int drm_syncobj_replace_fence(struct drm_file *file_private,
+			      u32 handle,
+			      struct dma_fence *fence);
+
+#endif

include/uapi/drm/drm.h +20 -0

index b2c5284..dd0b99c 100644
@@ -647,6 +647,7 @@ struct drm_gem_open {
  #define DRM_CAP_CURSOR_HEIGHT		0x9
  #define DRM_CAP_ADDFB2_MODIFIERS	0x10
  #define DRM_CAP_PAGE_FLIP_TARGET	0x11
+#define DRM_CAP_SYNCOBJ		0x13
 
  /** DRM_IOCTL_GET_CAP ioctl argument type */
  struct drm_get_cap {

@@ -696,6 +697,25 @@ struct drm_prime_handle {
  	__s32 fd;
  };
 
+struct drm_syncobj_create {
+	__u32 handle;
+	__u32 flags;
+};
+
+struct drm_syncobj_destroy {
+	__u32 handle;
+	__u32 pad;
+};
+
+struct drm_syncobj_handle {
+	__u32 handle;
+	/** Flags.. only applicable for handle->fd */
+	__u32 flags;
+
+	__s32 fd;
+	__u32 pad;
+};
+
  #if defined(__cplusplus)
  }
  #endif

@@ -814,6 +834,11 @@ extern "C" {
  #define DRM_IOCTL_MODE_CREATEPROPBLOB	DRM_IOWR(0xBD, struct drm_mode_create_blob)

From: Dave Airlie <[email protected]>

Sync objects are new toplevel drm object, that contain a pointer to a fence. This fence can be updated via command submission ioctls via drivers.

There is also a generic wait obj API modelled on the vulkan wait API (with code modelled on some amdgpu code).

These objects can be converted to an opaque fd that can be passes between processes.

TODO: define sync_file interaction.

Signed-off-by Dave Airlie <[email protected]>

---
  Documentation/gpu/drm-internals.rst |   3 +
  Documentation/gpu/drm-mm.rst        |   6 +
  drivers/gpu/drm/Makefile            |   2 +-
  drivers/gpu/drm/drm_fops.c          |   8 +
  drivers/gpu/drm/drm_internal.h      |  13 ++
  drivers/gpu/drm/drm_ioctl.c         |  12 ++
  drivers/gpu/drm/drm_syncobj.c       | 374 ++++++++++++++++++++++++++++++++++++
  include/drm/drmP.h                  |   5 +
  include/drm/drm_drv.h               |   1 +
  include/drm/drm_syncobj.h           | 104 ++++++++++
  include/uapi/drm/drm.h              |  25 +++
  11 files changed, 552 insertions(+), 1 deletion(-)

create mode 100644 drivers/gpu/drm/drm_syncobj.c create mode 100644 include/drm/drm_syncobj.h

Documentation/gpu/drm-internals.rst +3 -0

index e35920d..2ea3bce 100644
@@ -98,6 +98,9 @@ DRIVER_ATOMIC
      implement appropriate obj->atomic_get_property() vfuncs for any
      modeset objects with driver specific properties.
 
+DRIVER_SYNCOBJ
+    Driver support drm sync objects.
+
  Major, Minor and Patchlevel
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

Documentation/gpu/drm-mm.rst +6 -0

index f5760b1..28aebe8 100644
@@ -483,3 +483,9 @@ DRM Cache Handling
 
  .. kernel-doc:: drivers/gpu/drm/drm_cache.c
     :export:
+
+DRM Sync Objects
+===========================
+
+.. kernel-doc:: drivers/gpu/drm/drm_syncobj.c
+   :export:

drivers/gpu/drm/Makefile +1 -1

index 3ee9579..b5e565c 100644
@@ -16,7 +16,7 @@ drm-y       :=	drm_auth.o drm_bufs.o drm_cache.o \
  		drm_framebuffer.o drm_connector.o drm_blend.o \
  		drm_encoder.o drm_mode_object.o drm_property.o \
  		drm_plane.o drm_color_mgmt.o drm_print.o \
-		drm_dumb_buffers.o drm_mode_config.o
+		drm_dumb_buffers.o drm_mode_config.o drm_syncobj.o
 
  drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o
  drm-$(CONFIG_DRM_VM) += drm_vm.o

drivers/gpu/drm/drm_fops.c +8 -0

index afdf5b1..9a61df2 100644
@@ -219,6 +219,9 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
  	if (drm_core_check_feature(dev, DRIVER_GEM))
  		drm_gem_open(dev, priv);
 
+	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
+		drm_syncobj_open(priv);
+
  	if (drm_core_check_feature(dev, DRIVER_PRIME))
  		drm_prime_init_file_private(&priv->prime);
 

@@ -266,6 +269,8 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
  out_prime_destroy:
  	if (drm_core_check_feature(dev, DRIVER_PRIME))
  		drm_prime_destroy_file_private(&priv->prime);
+	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
+		drm_syncobj_release(priv);
  	if (drm_core_check_feature(dev, DRIVER_GEM))
  		drm_gem_release(dev, priv);
  	put_pid(priv->pid);

@@ -400,6 +405,9 @@ int drm_release(struct inode *inode, struct file *filp)
  		drm_property_destroy_user_blobs(dev, file_priv);
  	}
 
+	if (drm_core_check_feature(dev, DRIVER_SYNCOBJ))
+		drm_syncobj_release(file_priv);
+
  	if (drm_core_check_feature(dev, DRIVER_GEM))
  		drm_gem_release(dev, file_priv);
 

drivers/gpu/drm/drm_internal.h +13 -0

index f37388c..44ef903 100644
@@ -142,4 +142,17 @@ static inline int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
  {
  	return 0;
  }
+
  #endif
+
+/* drm_syncobj.c */
+void drm_syncobj_open(struct drm_file *file_private);
+void drm_syncobj_release(struct drm_file *file_private);
+int drm_syncobj_create_ioctl(struct drm_device *dev, void *data,
+			     struct drm_file *file_private);
+int drm_syncobj_destroy_ioctl(struct drm_device *dev, void *data,
+			      struct drm_file *file_private);
+int drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
+				   struct drm_file *file_private);
+int drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
+				   struct drm_file *file_private);

drivers/gpu/drm/drm_ioctl.c +12 -0

index a7c61c2..6da7adc 100644
@@ -240,6 +240,9 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
  		req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0;
  		req->value |= dev->driver->prime_handle_to_fd ? DRM_PRIME_CAP_EXPORT : 0;
  		return 0;
+	case DRM_CAP_SYNCOBJ:
+		req->value = drm_core_check_feature(dev, DRIVER_SYNCOBJ);
+		return 0;
  	}
 
  	/* Other caps only work with KMS drivers */

@@ -641,6 +644,15 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_ATOMIC, drm_mode_atomic_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATEPROPBLOB, drm_mode_createblob_ioctl, DRM_CONTROL_ALLOW|DRM_UNLOCKED),
  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_DESTROYPROPBLOB, drm_mode_destroyblob_ioctl, DRM_CONTROL_ALLOW|DRM_UNLOCKED),
+
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_CREATE, drm_syncobj_create_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_DESTROY, drm_syncobj_destroy_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD, drm_syncobj_handle_to_fd_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE, drm_syncobj_fd_to_handle_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
  };
 
  #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE( drm_ioctls )

drivers/gpu/drm/drm_syncobj.c new file +116 -0

new file mode 100644
index 0000000..e6a99d4
@@ -0,0 +1,374 @@
+/*
+ * Copyright 2017 Red Hat
+ *
+ * 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 export to fd's and back, these fd's are opaque and
+ * have no other use case, except passing the syncobj between processes.
+ *
+ * TODO: sync_file interactions, waiting
+ *
+ * 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 "drm_internal.h"
+#include <drm/drm_syncobj.h>
+
+static struct drm_syncobj *drm_syncobj_get(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_reference(syncobj);
+
+	spin_unlock(&file_private->syncobj_table_lock);
+
+	return syncobj;
+}
+
+/**
+ * drm_syncobj_replace_fence - lookup and replace fence in a sync object.
+ * @file_private - drm file private pointer.
+ * @handle - syncobj handle to lookup
+ * @fence - fence to install in sync file.
+ * Returns:
+ * 0 on success, or -EINVAL when the handle doesn't point at a valid sem file.
+ *
+ * This looks up a sync object and replaces the fence on it, freeing
+ * the old one.
+ */
+int drm_syncobj_replace_fence(struct drm_file *file_private,
+			      u32 handle,
+			      struct dma_fence *fence)
+{
+	struct drm_syncobj *syncobj = drm_syncobj_get(file_private, handle);
+	struct dma_fence *old_fence = NULL;
+
+	if (!syncobj)
+		return -EINVAL;
+
+	if (fence)
+		dma_fence_get(fence);
+	old_fence = xchg(&syncobj->fence, fence);
+
+	dma_fence_put(old_fence);
+	drm_syncobj_unreference(syncobj);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_syncobj_replace_fence);
+
+int drm_syncobj_fence_get(struct drm_file *file_private,
+			  u32 handle,
+			  struct dma_fence **fence)
+{
+	struct drm_syncobj *syncobj = drm_syncobj_get(file_private, handle);
+	int ret = 0;
+
+	if (!syncobj)
+		return -EINVAL;
+
+	*fence = dma_fence_get(syncobj->fence);
+	if (!*fence) {
+		ret = -EINVAL;
+	}

drivers/gpu/drm/drm_syncobj.c new file +248 -0

+	kfree(syncobj);
+}
+
+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;
+
+	mutex_init(&syncobj->file_lock);
+	kref_init(&syncobj->refcount);
+
+	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_unreference(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_unreference(syncobj);
+	return 0;
+}
+
+static int drm_syncobj_file_release(struct inode *inode, struct file *file)
+{
+	struct drm_syncobj *syncobj = file->private_data;
+
+	drm_syncobj_unreference(syncobj);
+	return 0;
+}
+
+static const struct file_operations drm_syncobj_file_fops = {
+	.release = drm_syncobj_file_release,
+};
+
+static int drm_syncobj_alloc_file_locked(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);
+
+	/* the file holds a reference to the object */
+	drm_syncobj_reference(syncobj);
+	syncobj->file = 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_get(file_private, handle);
+	int ret;
+	int fd;
+
+	if (!syncobj)
+		return -EINVAL;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0) {
+		drm_syncobj_unreference(syncobj);
+		return fd;
+	}
+
+	mutex_lock(&syncobj->file_lock);
+	if (!syncobj->file) {
+		ret = drm_syncobj_alloc_file_locked(syncobj);
+		if (ret)
+			goto out_unlock;
+	}
+	fd_install(fd, syncobj->file);
+	mutex_unlock(&syncobj->file_lock);
+	drm_syncobj_unreference(syncobj);
+	*p_fd = fd;
+	return 0;
+out_unlock:
+	put_unused_fd(fd);
+	mutex_unlock(&syncobj->file_lock);
+	drm_syncobj_unreference(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_reference(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;
+}
+
+/**
+ * drm_syncobj_open - initalizes syncobj file-private structures at devnode open time
+ * @dev: drm_device which is being opened by userspace
+ * @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_unreference(syncobj);
+	return 0;
+}
+
+/**
+ * drm_syncobj_release - release file-private sync object resources
+ * @dev: drm_device which is being closed by userspace
+ * @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;
+
+	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;
+
+	return drm_syncobj_fd_to_handle(file_private, args->fd,
+					&args->handle);
+}

include/drm/drmP.h +5 -0

index 6105c05..1d48f6f 100644
@@ -405,6 +405,11 @@ struct drm_file {
  	/** Lock for synchronization of access to object_idr. */
  	spinlock_t table_lock;
 
+	/** Mapping of sync object handles to object pointers. */
+	struct idr syncobj_idr;
+	/** Lock for synchronization of access to syncobj_idr. */
+	spinlock_t syncobj_table_lock;
+
  	struct file *filp;
  	void *driver_priv;
 

include/drm/drm_drv.h +1 -0

index 5699f42..48ff06b 100644
@@ -53,6 +53,7 @@ struct drm_mode_create_dumb;
  #define DRIVER_RENDER			0x8000
  #define DRIVER_ATOMIC			0x10000
  #define DRIVER_KMS_LEGACY_CONTEXT	0x20000
+#define DRIVER_SYNCOBJ                  0x40000
 
  /**
   * struct drm_driver - DRM driver structure

include/drm/drm_syncobj.h new file +104 -0

new file mode 100644
index 0000000..3cc42b7
@@ -0,0 +1,104 @@
+/*
+ * Copyright © 2017 Red Hat
+ *
+ * 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:
+ *
+ */
+#ifndef __DRM_SYNCOBJ_H__
+#define __DRM_SYNCOBJ_H__
+
+#include "linux/dma-fence.h"
+
+/**
+ * struct drm_syncobj - sync object.
+ *
+ * This structure defines a generic sync object which wraps a dma fence.
+ */
+struct drm_syncobj {
+	/**
+	 * @refcount:
+	 *
+	 * Reference count of this object.
+	 */
+	struct kref refcount;
+	/**
+	 * @fence:
+	 * NULL or a pointer to the fence bound to this object.
+	 */
+	struct dma_fence *fence;
+	/**
+	 * @file_lock
+	 * mutex protecting the struct file pointer.
+	 */
+	struct mutex file_lock;
+	/**
+	 * @file
+	 * a file backing for this syncobj.
+	 */
+	struct file *file;
+};
+
+void drm_syncobj_free(struct kref *kref);
+
+/**
+ * drm_gem_object_reference - acquire a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This acquires additional reference to @obj. It is illegal to call this
+ * without already holding a reference. No locks required.
+ */
+static inline void
+drm_syncobj_reference(struct drm_syncobj *obj)
+{
+	kref_get(&obj->refcount);
+}
+
+/**
+ * __drm_gem_object_unreference - raw function to release a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This function is meant to be used by drivers which are not encumbered with
+ * &drm_device.struct_mutex legacy locking and which are using the
+ * gem_free_object_unlocked callback. It avoids all the locking checks and
+ * locking overhead of drm_gem_object_unreference() and
+ * drm_gem_object_unreference_unlocked().
+ *
+ * Drivers should never call this directly in their code. Instead they should
+ * wrap it up into a ``driver_gem_object_unreference(struct driver_gem_object
+ * *obj)`` wrapper function, and use that. Shared code should never call this, to
+ * avoid breaking drivers by accident which still depend upon
+ * &drm_device.struct_mutex locking.
+ */
+static inline void
+drm_syncobj_unreference(struct drm_syncobj *obj)
+{
+	kref_put(&obj->refcount, drm_syncobj_free);
+}
+
+int drm_syncobj_fence_get(struct drm_file *file_private,
+			  u32 handle,
+			  struct dma_fence **fence);
+int drm_syncobj_replace_fence(struct drm_file *file_private,
+			      u32 handle,
+			      struct dma_fence *fence);
+
+#endif

include/uapi/drm/drm.h +20 -0

index b2c5284..dd0b99c 100644
@@ -647,6 +647,7 @@ struct drm_gem_open {
  #define DRM_CAP_CURSOR_HEIGHT		0x9
  #define DRM_CAP_ADDFB2_MODIFIERS	0x10
  #define DRM_CAP_PAGE_FLIP_TARGET	0x11
+#define DRM_CAP_SYNCOBJ		0x13
 
  /** DRM_IOCTL_GET_CAP ioctl argument type */
  struct drm_get_cap {

@@ -696,6 +697,25 @@ struct drm_prime_handle {
  	__s32 fd;
  };
 
+struct drm_syncobj_create {
+	__u32 handle;
+	__u32 flags;
+};
+
+struct drm_syncobj_destroy {
+	__u32 handle;
+	__u32 pad;
+};
+
+struct drm_syncobj_handle {
+	__u32 handle;
+	/** Flags.. only applicable for handle->fd */
+	__u32 flags;
+
+	__s32 fd;
+	__u32 pad;
+};
+
  #if defined(__cplusplus)
  }
  #endif

@@ -814,6 +834,11 @@ extern "C" {
  #define DRM_IOCTL_MODE_CREATEPROPBLOB	DRM_IOWR(0xBD, struct drm_mode_create_blob)

+#include <drm/drmP.h>

+static struct drm_syncobj *drm_syncobj_fdget(int fd)

drivers/gpu/drm/drm_syncobj.c new file +8 -0

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

drivers/gpu/drm/drm_syncobj.c new file +13 -0

+	fd_install(fd, syncobj->file);
+	mutex_unlock(&syncobj->file_lock);
+	drm_syncobj_unreference(syncobj);
+	*p_fd = fd;
+	return 0;
+out_unlock:
+	put_unused_fd(fd);
+	mutex_unlock(&syncobj->file_lock);
+	drm_syncobj_unreference(syncobj);
+	return ret;
+}
+
 
+/**

Quoted 1 line · Dave Airlie

+#include <drm/drmP.h>

I wonder if Daniel has already split everything used here into its own headers?

drivers/gpu/drm/drm_syncobj.c line 55

Quoted 3 lines

drivers/gpu/drm/drm_syncobj.c new file +3 -0

+
+static struct drm_syncobj *drm_syncobj_get(struct drm_file *file_private,
+                                        u32 handle)

I would like this exposed to the driver as well, so I can do handle to syncobj conversion once. (drm_syncobj_find() if we go with kref_get style naming.)

Quoted 2 lines

+static struct drm_syncobj *drm_syncobj_fdget(int fd)

It will aslo be useful to export the fd -> syncobj function for drivers. In the interface Jason has for execbuf, we can substitute the handle for an fd + flag, which may be more convenient for the user.

drivers/gpu/drm/drm_syncobj.c line 219

Quoted 2 lines

drivers/gpu/drm/drm_syncobj.c new file +2 -0

+     mutex_lock(&syncobj->file_lock);
+     if (!syncobj->file) {

Mutex only being used to ensure syncobj->file is set once? Is the race likely? If not, we can spare the mutex and just use a try instead:

We've been steadily converting to the kref_get style of nomenclature for drm object reference handling (i.e. drm_syncobj_get, drm_syncobj_put)

Quoted 5 lines · Chris Wilson

Quoted 1 line · Dave Airlie

+#include <drm/drmP.h>

I wonder if Daniel has already split everything used here into its own headers?

not sure, if drm_file is out there yet. I'll find out when I rebase this onto something newer I expect.

Quoted 7 lines

drivers/gpu/drm/drm_syncobj.c line 55

Quoted 3 lines

drivers/gpu/drm/drm_syncobj.c new file +3 -0

+
+static struct drm_syncobj *drm_syncobj_get(struct drm_file *file_private,
+                                        u32 handle)

I would like this exposed to the driver as well, so I can do handle to syncobj conversion once. (drm_syncobj_find() if we go with kref_get style naming.)

Where do you expect to need two lookups? At least for the semaphore APIs, you have a list of wait and list of signals, the lists should be different, I've no objections to exporting this later, but it would be easier to just do that with the first user.

Quoted 5 lines · Chris Wilson

Quoted 1 line · Dave Airlie

+#include <drm/drmP.h>

I wonder if Daniel has already split everything used here into its own headers?

not sure, if drm_file is out there yet. I'll find out when I rebase this onto something newer I expect.

Quoted 2 lines

Review

Quoted 2 lines

(quoted diff) +2 -0

+
+static struct drm_syncobj *drm_syncobj_get(struct drm_file

*file_private,

Quoted 5 lines

Quoted 1 line

+ u32 handle)

I would like this exposed to the driver as well, so I can do handle to syncobj conversion once. (drm_syncobj_find() if we go with kref_get style naming.)

Where do you expect to need two lookups? At least for the semaphore APIs, you have a list of wait and list of signals, the lists should be different, I've
no objections to exporting this later, but it would be easier to just do that
with the first user.

Quoted 4 lines

Quoted 2 lines

+static struct drm_syncobj *drm_syncobj_fdget(int fd)

It will aslo be useful to export the fd -> syncobj function for drivers.

In

Quoted 2 lines

the interface Jason has for execbuf, we can substitute the handle for an fd + flag, which may be more convenient for the user.

Happy once we have a use case for it, I'd rather we didn't expose the syncobj
fd to userspace for anything but sending a syncobj between processes, avoiding
using fd's is one of the main points of this, I'd hate for an API to demand we use
fd's.

From: Dave Airlie <[email protected]>

Sync objects are new toplevel drm object, that contain a pointer to a fence. This fence can be updated via command submission ioctls via drivers.

There is also a generic wait obj API modelled on the vulkan wait API (with code modelled on some amdgpu code).

These objects can be converted to an opaque fd that can be passes between processes.

TODO: define sync_file interaction.

Signed-off-by Dave Airlie <[email protected]>

include/drm/drm_syncobj.h new file +0 -0

new file mode 100644
index 0000000..3cc42b7

include/drm/drm_syncobj.h new file +18 -0

+/**
+ * drm_gem_object_reference - acquire a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This acquires additional reference to @obj. It is illegal to call this
+ * without already holding a reference. No locks required.
+ */
+static inline void
+drm_syncobj_reference(struct drm_syncobj *obj)
+{
+	kref_get(&obj->refcount);
+}
+
+/**
+ * __drm_gem_object_unreference - raw function to release a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This function is meant to be used by drivers which are not encumbered with

+ */

include/drm/drm_syncobj.h new file +14 -0

+static inline void
+drm_syncobj_unreference(struct drm_syncobj *obj)
+{
+	kref_put(&obj->refcount, drm_syncobj_free);
+}
+
+int drm_syncobj_fence_get(struct drm_file *file_private,
+			  u32 handle,
+			  struct dma_fence **fence);
+int drm_syncobj_replace_fence(struct drm_file *file_private,
+			      u32 handle,
+			      struct dma_fence *fence);
+
+#endif

include/uapi/drm/drm.h +25 -0

index b2c5284..dd0b99c 100644
@@ -647,6 +647,7 @@ struct drm_gem_open {
 #define DRM_CAP_CURSOR_HEIGHT		0x9
 #define DRM_CAP_ADDFB2_MODIFIERS	0x10
 #define DRM_CAP_PAGE_FLIP_TARGET	0x11
+#define DRM_CAP_SYNCOBJ		0x13
 
 /** DRM_IOCTL_GET_CAP ioctl argument type */
 struct drm_get_cap {

@@ -696,6 +697,25 @@ struct drm_prime_handle {
 	__s32 fd;
 };
 
+struct drm_syncobj_create {
+	__u32 handle;
+	__u32 flags;
+};
+
+struct drm_syncobj_destroy {
+	__u32 handle;
+	__u32 pad;
+};
+
+struct drm_syncobj_handle {
+	__u32 handle;
+	/** Flags.. only applicable for handle->fd */
+	__u32 flags;
+
+	__s32 fd;
+	__u32 pad;
+};
+
 #if defined(__cplusplus)
 }
 #endif

@@ -814,6 +834,11 @@ extern "C" {
 #define DRM_IOCTL_MODE_CREATEPROPBLOB	DRM_IOWR(0xBD, struct drm_mode_create_blob)
 #define DRM_IOCTL_MODE_DESTROYPROPBLOB	DRM_IOWR(0xBE, struct drm_mode_destroy_blob)
 
+#define DRM_IOCTL_SYNCOBJ_CREATE	DRM_IOWR(0xBF, struct drm_syncobj_create)
+#define DRM_IOCTL_SYNCOBJ_DESTROY	DRM_IOWR(0xC0, struct drm_syncobj_destroy)
+#define DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD	DRM_IOWR(0xC1, struct drm_syncobj_handle)
+#define DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE	DRM_IOWR(0xC2, struct drm_syncobj_handle)
+
 /**
  * Device specific ioctls should only be in their respective headers
  * The device specific ioctl range is from 0x40 to 0x9f.

Signature · 6 lines

2.9.3

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drivers/gpu/drm/drm_syncobj.c +39 -0

+/**
+ * calc_timeout - calculate jiffies timeout from absolute value
+ *
+ * @timeout_ns: timeout in ns
+ *
+ * Calculate the timeout in jiffies from an absolute timeout in ns.
+ */
+unsigned long calc_wait_timeout(uint64_t timeout_ns)
+{
+        unsigned long timeout_jiffies;
+        ktime_t timeout;
+
+        /* clamp timeout if it's to large */
+        if (((int64_t)timeout_ns) < 0)
+                return MAX_SCHEDULE_TIMEOUT;
+
+        timeout = ktime_sub(ns_to_ktime(timeout_ns), ktime_get());
+        if (ktime_to_ns(timeout) < 0)
+                return 0;
+
+        timeout_jiffies = nsecs_to_jiffies(ktime_to_ns(timeout));
+        /*  clamp timeout to avoid unsigned-> signed overflow */
+        if (timeout_jiffies > MAX_SCHEDULE_TIMEOUT )
+                return MAX_SCHEDULE_TIMEOUT - 1;
+
+        return timeout_jiffies;
+}
+
+static int drm_syncobj_wait_all_fences(struct drm_device *dev,
+				       struct drm_file *file_private,
+				       struct drm_syncobj_wait *wait,
+				       uint32_t *handles)
+{
+	uint32_t i;
+	int ret;
+
+	for (i = 0; i < wait->count_handles; i++) {
+		unsigned long timeout = calc_wait_timeout(wait->timeout_ns);
+		struct dma_fence *fence;

drivers/gpu/drm/drm_syncobj.c +11 -0

+		dma_fence_put(fence);
+		if (ret < 0)
+			return ret;
+		if (ret == 0)
+			break;
+	}
+
+	wait->out_status = (ret > 0);
+	wait->first_signaled = 0;
+	return 0;
+}

From: Dave Airlie <[email protected]>

This just splits out the fence depenency checking into it's own function to make it easier to add semaphore dependencies.

Reviewed-by Christian König <[email protected]>

Signed-off-by Dave Airlie <[email protected]>

---
  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 85 +++++++++++++++++++---------------
  1 file changed, 47 insertions(+), 38 deletions(-)

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c +0 -0

index 99424cb..df25b32 100644

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c +40 -35

+				    struct amdgpu_cs_chunk *chunk)
  {
  	struct amdgpu_fpriv *fpriv = p->filp->driver_priv;
-	int i, j, r;
-
-	for (i = 0; i < p->nchunks; ++i) {
-		struct drm_amdgpu_cs_chunk_dep *deps;
-		struct amdgpu_cs_chunk *chunk;
-		unsigned num_deps;
+	unsigned num_deps;
+	int i, r;
+	struct drm_amdgpu_cs_chunk_dep *deps;
 
-		chunk = &p->chunks[i];
+	deps = (struct drm_amdgpu_cs_chunk_dep *)chunk->kdata;
+	num_deps = chunk->length_dw * 4 /
+		sizeof(struct drm_amdgpu_cs_chunk_dep);
 
-		if (chunk->chunk_id != AMDGPU_CHUNK_ID_DEPENDENCIES)
-			continue;
+	for (i = 0; i < num_deps; ++i) {
+		struct amdgpu_ring *ring;
+		struct amdgpu_ctx *ctx;
+		struct dma_fence *fence;
 
-		deps = (struct drm_amdgpu_cs_chunk_dep *)chunk->kdata;
-		num_deps = chunk->length_dw * 4 /
-			sizeof(struct drm_amdgpu_cs_chunk_dep);
+		r = amdgpu_cs_get_ring(p->adev, deps[i].ip_type,
+				       deps[i].ip_instance,
+				       deps[i].ring, &ring);
+		if (r)
+			return r;
 
-		for (j = 0; j < num_deps; ++j) {
-			struct amdgpu_ring *ring;
-			struct amdgpu_ctx *ctx;
-			struct dma_fence *fence;
+		ctx = amdgpu_ctx_get(fpriv, deps[i].ctx_id);
+		if (ctx == NULL)
+			return -EINVAL;
 
-			r = amdgpu_cs_get_ring(adev, deps[j].ip_type,
-					       deps[j].ip_instance,
-					       deps[j].ring, &ring);
+		fence = amdgpu_ctx_get_fence(ctx, ring,
+					     deps[i].handle);
+		if (IS_ERR(fence)) {
+			r = PTR_ERR(fence);
+			amdgpu_ctx_put(ctx);
+			return r;
+		} else if (fence) {
+			r = amdgpu_sync_fence(p->adev, &p->job->sync,
+					      fence);
+			dma_fence_put(fence);
+			amdgpu_ctx_put(ctx);
  			if (r)
  				return r;
+		}
+	}
+	return 0;
+}
 
-			ctx = amdgpu_ctx_get(fpriv, deps[j].ctx_id);
-			if (ctx == NULL)
-				return -EINVAL;
+static int amdgpu_cs_dependencies(struct amdgpu_device *adev,
+				  struct amdgpu_cs_parser *p)
+{
+	int i, r;
 
-			fence = amdgpu_ctx_get_fence(ctx, ring,
-						     deps[j].handle);
-			if (IS_ERR(fence)) {
-				r = PTR_ERR(fence);
-				amdgpu_ctx_put(ctx);
-				return r;
+	for (i = 0; i < p->nchunks; ++i) {
+		struct amdgpu_cs_chunk *chunk;
 
-			} else if (fence) {
-				r = amdgpu_sync_fence(adev, &p->job->sync,
-						      fence);
-				dma_fence_put(fence);
-				amdgpu_ctx_put(ctx);
-				if (r)
-					return r;

Okay I've gone around the sun with these a few times, and pretty much implemented what I said last week.

This is pretty much a complete revamp.

1. sync objects are self contained drm objects, they have a file reference so can be passed between processes.

2. Added a sync object wait interface modelled on the vulkan fence waiting API.

3. sync_file interaction is explicitly different than opaque fd passing, you import a sync file state into an existing syncobj, or create a new sync_file from an existing syncobj. This means no touching the sync file code at all. \o/

I haven't used rcu anywhere here, I've used xchg to swap fence pointers in the hope that's safe. If this does need rcu'ing I suggest we do it in a follow on patch to minimise the review pain.

Dave.

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Am 26.04.2017 um 05:28 schrieb Dave Airlie:

Quoted 9 lines

Okay I've gone around the sun with these a few times, and pretty much implemented what I said last week.

This is pretty much a complete revamp.

1. sync objects are self contained drm objects, they have a file reference so can be passed between processes.

Quoted 8 lines

2. Added a sync object wait interface modelled on the vulkan fence waiting API.

3. sync_file interaction is explicitly different than opaque fd passing, you import a sync file state into an existing syncobj, or create a new sync_file from an existing syncobj. This means no touching the sync file code at all. \o/

Doesn't that break the Vulkan requirement that if a sync_obj is exported to an fd and imported on the other side we get the same sync_obj again?

In other words the fd is exported and imported only once and the expectation is that we fence containing it will change on each signaling operation.

As far as I can see with the current implementation you get two sync_objects on in the exporting process and one in the importing one.

Quoted 18 lines

Am 26.04.2017 um 05:28 schrieb Dave Airlie:

Quoted 8 lines

Okay I've gone around the sun with these a few times, and pretty much implemented what I said last week.

This is pretty much a complete revamp.

1. sync objects are self contained drm objects, they have a file reference so can be passed between processes.

Quoted 8 lines

2. Added a sync object wait interface modelled on the vulkan fence waiting API.

3. sync_file interaction is explicitly different than opaque fd passing, you import a sync file state into an existing syncobj, or create a new sync_file from an existing syncobj. This means no touching the sync file code at all. \o/

Quoted 8 lines

Doesn't that break the Vulkan requirement that if a sync_obj is exported to an fd and imported on the other side we get the same sync_obj again?

In other words the fd is exported and imported only once and the expectation is that we fence containing it will change on each signaling operation.

As far as I can see with the current implementation you get two sync_objects on in the exporting process and one in the importing one.

Are you talking about using sync_file interop for vulkan, then yes that would be wrong.

But that isn't how this works, see 1. above the sync obj has a 1:1 mapping with an
opaque fd (non-sync_file) that is only used for interprocess passing of the syncobj.

You can interoperate with sync_files by importing/exporting the syncobj fence into
and out of them but that aren't meant for passing the fds around, more for where you
get a sync_file fd from somewhere else and you want to use it and vice-versa.

I'd like to move any drm APIs away from sync_file to avoid the fd wastages,

I'd also like to move the driver specific fences to syncobj where I can.

Dave.

Am 26.04.2017 um 11:57 schrieb Dave Airlie:

Quoted 23 lines

Quoted 20 lines · Christian König

Am 26.04.2017 um 05:28 schrieb Dave Airlie:

Quoted 17 lines

Okay I've gone around the sun with these a few times, and pretty much implemented what I said last week.

This is pretty much a complete revamp.

1. sync objects are self contained drm objects, they have a file reference so can be passed between processes.

2. Added a sync object wait interface modelled on the vulkan fence waiting API.

3. sync_file interaction is explicitly different than opaque fd passing, you import a sync file state into an existing syncobj, or create a new sync_file from an existing syncobj. This means no touching the sync file code at all. \o/

Doesn't that break the Vulkan requirement that if a sync_obj is exported to

Quoted 10 lines

Quoted 10 lines

an fd and imported on the other side we get the same sync_obj again?

In other words the fd is exported and imported only once and the expectation
is that we fence containing it will change on each signaling operation.

As far as I can see with the current implementation you get two sync_objects
on in the exporting process and one in the importing one.

Quoted 8 lines

Are you talking about using sync_file interop for vulkan, then yes that would be wrong.

But that isn't how this works, see 1. above the sync obj has a 1:1 mapping with an
opaque fd (non-sync_file) that is only used for interprocess passing of the syncobj.

Ah, ok that makes some more sense.

You can interoperate with sync_files by importing/exporting the

Quoted 6 lines

syncobj fence into
and out of them but that aren't meant for passing the fds around, more for where you
get a sync_file fd from somewhere else and you want to use it and vice-versa.

I would prefer dealing only with one type of fd in userspace, but that approach should work as well.

I'd like to move any drm APIs away from sync_file to avoid the fd wastages,

Quoted 1 line

That sounds like it make sense, but I would still rather vote for extending the sync_file interface than deprecating it with another one.

I'd also like to move the driver specific fences to syncobj where I can.

Quoted 1 line

I'm pretty sure that is not a good idea.

Beating the sequence based fence values we currently use for CPU sync in performance would be pretty hard. E.g. at least on amdgpu we can even check those by doing a simple 64bit read from a memory address, without IOCTL or any other overhead involved.

Regards,
Christian.

Quoted 2 lines

Dave.

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