dmabuf: implement linux_dmabuf extension

v2 changes:
- implement the revised protocol
- add basic sanity checks when creating buffer and check for support
- add way to attach user data to the dmabuf for renderer use
- bump max number of planes to 4 to follow DRM AddFb2 ioctl
- improve errors handling
- use separate linux_dmabuf_buffer fields for the different wl_resource
  types
- as SERVER_ERROR code is no more, use a wl_display "generic" error for
  emergency-disconneting a client we fail to process
- more documentation
- change y-invert from per-plane boolean to per-buffer flag

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

Makefile.am

@@ -87,6 +87,8 @@ weston_SOURCES =					\
 	src/timeline.h					\
 	src/timeline-object.h				\
 	src/main.c					\
+	src/linux-dmabuf.c				\
+	src/linux-dmabuf.h				\
 	shared/helpers.h				\
 	shared/matrix.c					\
 	shared/matrix.h					\

src/compositor.c

@@ -4672,6 +4672,34 @@ weston_compositor_read_presentation_clock(
 	}
 }
 
+/** Import dmabuf buffer into current renderer
+ *
+ * \param compositor
+ * \param buffer the dmabuf buffer to import
+ * \return true on usable buffers, false otherwise
+ *
+ * This function tests that the linux_dmabuf_buffer is usable
+ * for the current renderer. Returns false on unusable buffers. Usually
+ * usability is tested by importing the dmabufs for composition.
+ *
+ * This hook is also used for detecting if the renderer supports
+ * dmabufs at all. If the renderer hook is NULL, dmabufs are not
+ * supported.
+ * */
+WL_EXPORT bool
+weston_compositor_import_dmabuf(struct weston_compositor *compositor,
+				struct linux_dmabuf_buffer *buffer)
+{
+	struct weston_renderer *renderer;
+
+	renderer = compositor->renderer;
+
+	if (renderer->import_dmabuf == NULL)
+		return false;
+
+	return renderer->import_dmabuf(compositor, buffer);
+}
+
 WL_EXPORT void
 weston_version(int *major, int *minor, int *micro)
 {

src/compositor.h

@@ -57,6 +57,7 @@ struct weston_seat;
 struct weston_output;
 struct input_method;
 struct weston_pointer;
+struct linux_dmabuf_buffer;
 
 enum weston_keyboard_modifier {
 	MODIFIER_CTRL = (1 << 0),
@@ -588,6 +589,10 @@ struct weston_renderer {
 				    void *target, size_t size,
 				    int src_x, int src_y,
 				    int width, int height);
+
+	/** See weston_compositor_import_dmabuf() */
+	bool (*import_dmabuf)(struct weston_compositor *ec,
+			      struct linux_dmabuf_buffer *buffer);
 };
 
 enum weston_capability {
@@ -1364,6 +1369,10 @@ weston_compositor_read_presentation_clock(
 			const struct weston_compositor *compositor,
 			struct timespec *ts);
 
+bool
+weston_compositor_import_dmabuf(struct weston_compositor *compositor,
+				struct linux_dmabuf_buffer *buffer);
+
 void
 weston_compositor_shutdown(struct weston_compositor *ec);
 void

src/linux-dmabuf.c

@@ -0,0 +1,497 @@
+/*
+ * Copyright © 2014, 2015 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <assert.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "compositor.h"
+#include "linux-dmabuf.h"
+#include "linux-dmabuf-server-protocol.h"
+
+static void
+linux_dmabuf_buffer_destroy(struct linux_dmabuf_buffer *buffer)
+{
+	int i;
+
+	for (i = 0; i < buffer->n_planes; i++) {
+		close(buffer->dmabuf_fd[i]);
+		buffer->dmabuf_fd[i] = -1;
+	}
+
+	buffer->n_planes = 0;
+	free(buffer);
+}
+
+static void
+destroy_params(struct wl_resource *params_resource)
+{
+	struct linux_dmabuf_buffer *buffer;
+
+	buffer = wl_resource_get_user_data(params_resource);
+
+	if (!buffer)
+		return;
+
+	linux_dmabuf_buffer_destroy(buffer);
+}
+
+static void
+params_destroy(struct wl_client *client, struct wl_resource *resource)
+{
+	wl_resource_destroy(resource);
+}
+
+static void
+params_add(struct wl_client *client,
+	   struct wl_resource *params_resource,
+	   int32_t name_fd,
+	   uint32_t plane_idx,
+	   uint32_t offset,
+	   uint32_t stride,
+	   uint32_t modifier_hi,
+	   uint32_t modifier_lo)
+{
+	struct linux_dmabuf_buffer *buffer;
+
+	buffer = wl_resource_get_user_data(params_resource);
+	if (!buffer) {
+		wl_resource_post_error(params_resource,
+			ZLINUX_BUFFER_PARAMS_ERROR_ALREADY_USED,
+			"params was already used to create a wl_buffer");
+		close(name_fd);
+		return;
+	}
+
+	assert(buffer->params_resource == params_resource);
+	assert(!buffer->buffer_resource);
+
+	if (plane_idx >= MAX_DMABUF_PLANES) {
+		wl_resource_post_error(params_resource,
+			ZLINUX_BUFFER_PARAMS_ERROR_PLANE_IDX,
+			"plane index %u is too high", plane_idx);
+		close(name_fd);
+		return;
+	}
+
+	if (buffer->dmabuf_fd[plane_idx] != -1) {
+		wl_resource_post_error(params_resource,
+			ZLINUX_BUFFER_PARAMS_ERROR_PLANE_SET,
+			"a dmabuf has already been added for plane %u",
+			plane_idx);
+		close(name_fd);
+		return;
+	}
+
+	buffer->dmabuf_fd[plane_idx] = name_fd;
+	buffer->offset[plane_idx] = offset;
+	buffer->stride[plane_idx] = stride;
+	buffer->modifier[plane_idx] = ((uint64_t)modifier_hi << 32) |
+				      modifier_lo;
+	buffer->n_planes++;
+}
+
+static void
+linux_dmabuf_wl_buffer_destroy(struct wl_client *client,
+			       struct wl_resource *resource)
+{
+	wl_resource_destroy(resource);
+}
+
+static const struct wl_buffer_interface linux_dmabuf_buffer_implementation = {
+	linux_dmabuf_wl_buffer_destroy
+};
+
+static void
+destroy_linux_dmabuf_wl_buffer(struct wl_resource *resource)
+{
+	struct linux_dmabuf_buffer *buffer;
+
+	buffer = wl_resource_get_user_data(resource);
+	assert(buffer->buffer_resource == resource);
+	assert(!buffer->params_resource);
+
+	if (buffer->user_data_destroy_func)
+		buffer->user_data_destroy_func(buffer);
+
+	linux_dmabuf_buffer_destroy(buffer);
+}
+
+static void
+params_create(struct wl_client *client,
+	      struct wl_resource *params_resource,
+	      int32_t width,
+	      int32_t height,
+	      uint32_t format,
+	      uint32_t flags)
+{
+	struct linux_dmabuf_buffer *buffer;
+	int i;
+
+	buffer = wl_resource_get_user_data(params_resource);
+
+	if (!buffer) {
+		wl_resource_post_error(params_resource,
+			ZLINUX_BUFFER_PARAMS_ERROR_ALREADY_USED,
+			"params was already used to create a wl_buffer");
+		return;
+	}
+
+	assert(buffer->params_resource == params_resource);
+	assert(!buffer->buffer_resource);
+
+	/* Switch the linux_dmabuf_buffer object from params resource to
+	 * eventually wl_buffer resource.
+	 */
+	wl_resource_set_user_data(buffer->params_resource, NULL);
+	buffer->params_resource = NULL;
+
+	if (!buffer->n_planes) {
+		wl_resource_post_error(params_resource,
+			ZLINUX_BUFFER_PARAMS_ERROR_INCOMPLETE,
+			"no dmabuf has been added to the params");
+		goto err_out;
+	}
+
+	/* Check for holes in the dmabufs set (e.g. [0, 1, 3]) */
+	for (i = 0; i < buffer->n_planes; i++) {
+		if (buffer->dmabuf_fd[i] == -1) {
+			wl_resource_post_error(params_resource,
+				ZLINUX_BUFFER_PARAMS_ERROR_INCOMPLETE,
+				"no dmabuf has been added for plane %i", i);
+			goto err_out;
+		}
+	}
+
+	buffer->width = width;
+	buffer->height = height;
+	buffer->format = format;
+	buffer->flags = flags;
+
+	if (width < 1 || height < 1) {
+		wl_resource_post_error(params_resource,
+			ZLINUX_BUFFER_PARAMS_ERROR_INVALID_DIMENSIONS,
+			"invalid width %d or height %d", width, height);
+		goto err_out;
+	}
+
+	for (i = 0; i < buffer->n_planes; i++) {
+		off_t size;
+
+		if ((uint64_t) buffer->offset[i] + buffer->stride[i] > UINT32_MAX) {
+			wl_resource_post_error(params_resource,
+				ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+				"size overflow for plane %i", i);
+			goto err_out;
+		}
+
+		if (i == 0 &&
+		   (uint64_t) buffer->offset[i] +
+		   (uint64_t) buffer->stride[i] * height > UINT32_MAX) {
+			wl_resource_post_error(params_resource,
+				ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+				"size overflow for plane %i", i);
+			goto err_out;
+		}
+
+		/* Don't report an error as it might be caused
+		 * by the kernel not supporting seeking on dmabuf */
+		size = lseek(buffer->dmabuf_fd[i], 0, SEEK_END);
+		if (size == -1)
+			break;
+
+		if (buffer->offset[i] >= size) {
+			wl_resource_post_error(params_resource,
+				ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+				"invalid offset %i for plane %i",
+				buffer->offset[i], i);
+			goto err_out;
+		}
+
+		if (buffer->offset[i] + buffer->stride[i] > size) {
+			wl_resource_post_error(params_resource,
+				ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+				"invalid stride %i for plane %i",
+				buffer->stride[i], i);
+			goto err_out;
+		}
+
+		/* Only valid for first plane as other planes might be
+		 * sub-sampled according to fourcc format */
+		if (i == 0 &&
+		    buffer->offset[i] + buffer->stride[i] * height > size) {
+			wl_resource_post_error(params_resource,
+				ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+				"invalid buffer stride or height for plane %i", i);
+			goto err_out;
+		}
+	}
+
+	/* XXX: Some additional sanity checks could be done with respect
+	 * to the fourcc format. A centralized collection (kernel or
+	 * libdrm) would be useful to avoid code duplication for these
+	 * checks (e.g. drm_format_num_planes).
+	 */
+
+	if (!weston_compositor_import_dmabuf(buffer->compositor, buffer))
+		goto err_failed;
+
+	buffer->buffer_resource = wl_resource_create(client,
+						     &wl_buffer_interface,
+						     1, 0);
+	if (!buffer->buffer_resource) {
+		wl_resource_post_no_memory(params_resource);
+		goto err_buffer;
+	}
+
+	wl_resource_set_implementation(buffer->buffer_resource,
+				       &linux_dmabuf_buffer_implementation,
+				       buffer, destroy_linux_dmabuf_wl_buffer);
+
+	zlinux_buffer_params_send_created(params_resource,
+					  buffer->buffer_resource);
+
+	return;
+
+err_buffer:
+	if (buffer->user_data_destroy_func)
+		buffer->user_data_destroy_func(buffer);
+
+err_failed:
+	zlinux_buffer_params_send_failed(params_resource);
+
+err_out:
+	linux_dmabuf_buffer_destroy(buffer);
+}
+
+static const struct zlinux_buffer_params_interface
+zlinux_buffer_params_implementation = {
+	params_destroy,
+	params_add,
+	params_create
+};
+
+static void
+linux_dmabuf_destroy(struct wl_client *client, struct wl_resource *resource)
+{
+	wl_resource_destroy(resource);
+}
+
+static void
+linux_dmabuf_create_params(struct wl_client *client,
+			   struct wl_resource *linux_dmabuf_resource,
+			   uint32_t params_id)
+{
+	struct weston_compositor *compositor;
+	struct linux_dmabuf_buffer *buffer;
+	uint32_t version;
+	int i;
+
+	version = wl_resource_get_version(linux_dmabuf_resource);
+	compositor = wl_resource_get_user_data(linux_dmabuf_resource);
+
+	buffer = zalloc(sizeof *buffer);
+	if (!buffer)
+		goto err_out;
+
+	for (i = 0; i < MAX_DMABUF_PLANES; i++)
+		buffer->dmabuf_fd[i] = -1;
+
+	buffer->compositor = compositor;
+	buffer->params_resource =
+		wl_resource_create(client,
+				   &zlinux_buffer_params_interface,
+				   version, params_id);
+	if (!buffer->params_resource)
+		goto err_dealloc;
+
+	wl_resource_set_implementation(buffer->params_resource,
+				       &zlinux_buffer_params_implementation,
+				       buffer, destroy_params);
+
+	return;
+
+err_dealloc:
+	free(buffer);
+
+err_out:
+	wl_resource_post_no_memory(linux_dmabuf_resource);
+}
+
+/** Get the linux_dmabuf_buffer from a wl_buffer resource
+ *
+ * If the given wl_buffer resource was created through the linux_dmabuf
+ * protocol interface, returns the linux_dmabuf_buffer object. This can
+ * be used as a type check for a wl_buffer.
+ *
+ * \param resource A wl_buffer resource.
+ * \return The linux_dmabuf_buffer if it exists, or NULL otherwise.
+ */
+WL_EXPORT struct linux_dmabuf_buffer *
+linux_dmabuf_buffer_get(struct wl_resource *resource)
+{
+	struct linux_dmabuf_buffer *buffer;
+
+	if (!resource)
+		return NULL;
+
+	if (!wl_resource_instance_of(resource, &wl_buffer_interface,
+				     &linux_dmabuf_buffer_implementation))
+		return NULL;
+
+	buffer = wl_resource_get_user_data(resource);
+	assert(buffer);
+	assert(!buffer->params_resource);
+	assert(buffer->buffer_resource == resource);
+
+	return buffer;
+}
+
+/** Set renderer-private data
+ *
+ * Set the user data for the linux_dmabuf_buffer. It is invalid to overwrite
+ * a non-NULL user data with a new non-NULL pointer. This is meant to
+ * protect against renderers fighting over linux_dmabuf_buffer user data
+ * ownership.
+ *
+ * The renderer-private data is usually set from the
+ * weston_renderer::import_dmabuf hook.
+ *
+ * \param buffer The linux_dmabuf_buffer object to set for.
+ * \param data The new renderer-private data pointer.
+ * \param func Destructor function to be called for the renderer-private
+ *             data when the linux_dmabuf_buffer gets destroyed.
+ *
+ * \sa weston_compositor_import_dmabuf
+ */
+WL_EXPORT void
+linux_dmabuf_buffer_set_user_data(struct linux_dmabuf_buffer *buffer,
+				  void *data,
+				  dmabuf_user_data_destroy_func func)
+{
+	assert(data == NULL || buffer->user_data == NULL);
+
+	buffer->user_data = data;
+	buffer->user_data_destroy_func = func;
+}
+
+/** Get renderer-private data
+ *
+ * Get the user data from the linux_dmabuf_buffer.
+ *
+ * \param buffer The linux_dmabuf_buffer to query.
+ * \return Renderer-private data pointer.
+ *
+ * \sa linux_dmabuf_buffer_set_user_data
+ */
+WL_EXPORT void *
+linux_dmabuf_buffer_get_user_data(struct linux_dmabuf_buffer *buffer)
+{
+	return buffer->user_data;
+}
+
+static const struct zlinux_dmabuf_interface linux_dmabuf_implementation = {
+	linux_dmabuf_destroy,
+	linux_dmabuf_create_params
+};
+
+static void
+bind_linux_dmabuf(struct wl_client *client,
+		  void *data, uint32_t version, uint32_t id)
+{
+	struct weston_compositor *compositor = data;
+	struct wl_resource *resource;
+
+	resource = wl_resource_create(client, &zlinux_dmabuf_interface,
+				      version, id);
+	if (resource == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+
+	wl_resource_set_implementation(resource, &linux_dmabuf_implementation,
+				       compositor, NULL);
+
+	/* EGL_EXT_image_dma_buf_import does not provide a way to query the
+	 * supported pixel formats. */
+	/* XXX: send formats */
+}
+
+/** Advertise linux_dmabuf support
+ *
+ * Calling this initializes the zlinux_dmabuf protocol support, so that
+ * the interface will be advertised to clients. Essentially it creates a
+ * global. Do not call this function multiple times in the compositor's
+ * lifetime. There is no way to deinit explicitly, globals will be reaped
+ * when the wl_display gets destroyed.
+ *
+ * \param compositor The compositor to init for.
+ * \return Zero on success, -1 on failure.
+ */
+WL_EXPORT int
+linux_dmabuf_setup(struct weston_compositor *compositor)
+{
+	if (!wl_global_create(compositor->wl_display,
+			      &zlinux_dmabuf_interface, 1,
+			      compositor, bind_linux_dmabuf))
+		return -1;
+
+	return 0;
+}
+
+/** Resolve an internal compositor error by disconnecting the client.
+ *
+ * This function is used in cases when the dmabuf-based wl_buffer
+ * turns out unusable and there is no fallback path. This is used by
+ * renderers which are the fallback path in the first place.
+ *
+ * It is possible the fault is caused by a compositor bug, the underlying
+ * graphics stack bug or normal behaviour, or perhaps a client mistake.
+ * In any case, the options are to either composite garbage or nothing,
+ * or disconnect the client. This is a helper function for the latter.
+ *
+ * The error is sent as a INVALID_OBJECT error on the client's wl_display.
+ *
+ * \param buffer The linux_dmabuf_buffer that is unusable.
+ * \param msg A custom error message attached to the protocol error.
+ */
+WL_EXPORT void
+linux_dmabuf_buffer_send_server_error(struct linux_dmabuf_buffer *buffer,
+				      const char *msg)
+{
+	struct wl_client *client;
+	struct wl_resource *display_resource;
+	uint32_t id;
+
+	assert(buffer->buffer_resource);
+	id = wl_resource_get_id(buffer->buffer_resource);
+	client = wl_resource_get_client(buffer->buffer_resource);
+	display_resource = wl_client_get_object(client, 1);
+
+	assert(display_resource);
+	wl_resource_post_error(display_resource,
+			       WL_DISPLAY_ERROR_INVALID_OBJECT,
+			       "linux_dmabuf server error with "
+			       "wl_buffer@%u: %s", id, msg);
+}

src/linux-dmabuf.h

@@ -0,0 +1,84 @@
+/*
+ * Copyright © 2014, 2015 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef WESTON_LINUX_DMABUF_H
+#define WESTON_LINUX_DMABUF_H
+
+#include <stdint.h>
+
+#define MAX_DMABUF_PLANES 4
+
+struct linux_dmabuf_buffer;
+typedef void (*dmabuf_user_data_destroy_func)(
+			struct linux_dmabuf_buffer *buffer);
+
+struct linux_dmabuf_buffer {
+	struct wl_resource *buffer_resource;
+	struct wl_resource *params_resource;
+	struct weston_compositor *compositor;
+	int32_t width;
+	int32_t height;
+	uint32_t format;
+	uint32_t flags; /* enum zlinux_buffer_params_flags */
+	int n_planes;
+	int dmabuf_fd[MAX_DMABUF_PLANES];
+	uint32_t offset[MAX_DMABUF_PLANES];
+	uint32_t stride[MAX_DMABUF_PLANES];
+	uint64_t modifier[MAX_DMABUF_PLANES];
+
+	void *user_data;
+	dmabuf_user_data_destroy_func user_data_destroy_func;
+
+	/* XXX:
+	 *
+	 * Add backend private data. This would be for the backend
+	 * to do all additional imports it might ever use in advance.
+	 * The basic principle, even if not implemented in drivers today,
+	 * is that dmabufs are first attached, but the actual allocation
+	 * is deferred to first use. This would allow the exporter and all
+	 * attachers to agree on how to allocate.
+	 *
+	 * The DRM backend would use this to create drmFBs for each
+	 * dmabuf_buffer, just in case at some point it would become
+	 * feasible to scan it out directly. This would improve the
+	 * possibilities to successfully scan out, avoiding compositing.
+	 */
+};
+
+int
+linux_dmabuf_setup(struct weston_compositor *compositor);
+
+struct linux_dmabuf_buffer *
+linux_dmabuf_buffer_get(struct wl_resource *resource);
+
+void
+linux_dmabuf_buffer_set_user_data(struct linux_dmabuf_buffer *buffer,
+				  void *data,
+				  dmabuf_user_data_destroy_func func);
+void *
+linux_dmabuf_buffer_get_user_data(struct linux_dmabuf_buffer *buffer);
+
+void
+linux_dmabuf_buffer_send_server_error(struct linux_dmabuf_buffer *buffer,
+				      const char *msg);
+
+#endif /* WESTON_LINUX_DMABUF_H */