libweston: Introduce an internal linux sync file API

Introduce an internal API for dealing with linux sync files,
and use it in the codebase to replace ad-hoc sync file management.

The linux_sync_file_is_valid function is not currently used, but will be
utilized in upcoming commits to implement the
zwp_linux_explicit_synchronization_unstable_v1 protocol.

Changes in v5:
  - Meson support.

Changes in v3:
  - Use parameter name in function documentation.
  - Move kernel UAPI to separate header file.

Changes in v2:
  - Add function documentation
  - Remove linux_sync_file_wait()

Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>

Makefile.am

@@ -340,7 +340,9 @@ gl_renderer_la_SOURCES =			\
 	libweston/gl-renderer.c			\
 	libweston/vertex-clipping.c		\
 	libweston/vertex-clipping.h		\
-	libweston/weston-sync-file.h		\
+	libweston/linux-sync-file.c		\
+	libweston/linux-sync-file.h		\
+	libweston/linux-sync-file-uapi.h	\
 	shared/helpers.h
 endif
 

libweston/gl-renderer.c

@@ -40,13 +40,8 @@
 #include <linux/input.h>
 #include <drm_fourcc.h>
 #include <unistd.h>
-#include <sys/ioctl.h>
 
-#ifdef HAVE_LINUX_SYNC_FILE_H
-#include <linux/sync_file.h>
-#else
-#include "weston-sync-file.h"
-#endif
+#include "linux-sync-file.h"
 
 #include "timeline.h"
 
@@ -315,25 +310,6 @@ get_renderer(struct weston_compositor *ec)
 	return (struct gl_renderer *)ec->renderer;
 }
 
-static int
-linux_sync_file_read_timestamp(int fd, uint64_t *ts)
-{
-	struct sync_file_info file_info = { { 0 } };
-	struct sync_fence_info fence_info = { { 0 } };
-
-	assert(ts != NULL);
-
-	file_info.sync_fence_info = (uint64_t)(uintptr_t)&fence_info;
-	file_info.num_fences = 1;
-
-	if (ioctl(fd, SYNC_IOC_FILE_INFO, &file_info) < 0)
-		return -1;
-
-	*ts = fence_info.timestamp_ns;
-
-	return 0;
-}
-
 static void
 timeline_render_point_destroy(struct timeline_render_point *trp)
 {
@@ -351,13 +327,9 @@ timeline_render_point_handler(int fd, uint32_t mask, void *data)
 			      "renderer_gpu_begin" : "renderer_gpu_end";
 
 	if (mask & WL_EVENT_READABLE) {
-		uint64_t ts;
-
-		if (linux_sync_file_read_timestamp(trp->fd, &ts) == 0) {
-			struct timespec tspec = { 0 };
-
-			timespec_add_nsec(&tspec, &tspec, ts);
+		struct timespec tspec = { 0 };
 
+		if (linux_sync_file_read_timestamp(trp->fd, &tspec) == 0) {
 			TL_POINT(tp_name, TLP_GPU(&tspec),
 				 TLP_OUTPUT(trp->output), TLP_END);
 		}

libweston/linux-sync-file-uapi.h

@@ -1,7 +1,7 @@
 /* Sync file Linux kernel UAPI */
 
-#ifndef WESTON_SYNC_FILE_H
-#define WESTON_SYNC_FILE_H
+#ifndef WESTON_LINUX_SYNC_FILE_UAPI_H
+#define WESTON_LINUX_SYNC_FILE_UAPI_H
 
 #include <linux/ioctl.h>
 #include <linux/types.h>
@@ -27,4 +27,4 @@ struct sync_file_info {
 #define SYNC_IOC_MAGIC '>'
 #define SYNC_IOC_FILE_INFO _IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
 
-#endif
+#endif /* WESTON_LINUX_SYNC_FILE_UAPI_H */

libweston/linux-sync-file.c

@@ -0,0 +1,82 @@
+/*
+ * Copyright © 2018 Collabora, Ltd
+ *
+ * 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.
+ */
+
+#include "config.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <poll.h>
+#include <stddef.h>
+#include <sys/ioctl.h>
+
+#ifdef HAVE_LINUX_SYNC_FILE_H
+#include <linux/sync_file.h>
+#else
+#include "linux-sync-file-uapi.h"
+#endif
+
+#include "linux-sync-file.h"
+#include "shared/timespec-util.h"
+
+/* Check that a file descriptor represents a valid sync file
+ *
+ * \param fd[in] a file descriptor
+ * \return true if fd is a valid sync file, false otherwise
+ */
+bool
+linux_sync_file_is_valid(int fd)
+{
+	struct sync_file_info file_info = { { 0 } };
+
+	if (ioctl(fd, SYNC_IOC_FILE_INFO, &file_info) < 0)
+		return false;
+
+	return file_info.num_fences > 0;
+}
+
+/* Read the timestamp stored in a sync file
+ *
+ * \param fd[in] fd a file descriptor for a sync file
+ * \param ts[out] the timespec struct to fill with the timestamp
+ * \return 0 if a timestamp was read, -1 on error
+ */
+int
+linux_sync_file_read_timestamp(int fd, struct timespec *ts)
+{
+	struct sync_file_info file_info = { { 0 } };
+	struct sync_fence_info fence_info = { { 0 } };
+
+	assert(ts != NULL);
+
+	file_info.sync_fence_info = (uint64_t)(uintptr_t)&fence_info;
+	file_info.num_fences = 1;
+
+	if (ioctl(fd, SYNC_IOC_FILE_INFO, &file_info) < 0)
+		return -1;
+
+	timespec_from_nsec(ts, fence_info.timestamp_ns);
+
+	return 0;
+}

libweston/linux-sync-file.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright © 2018 Collabora, Ltd
+ *
+ * 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.
+ */
+
+#ifndef WESTON_LINUX_SYNC_FILE_H
+#define WESTON_LINUX_SYNC_FILE_H
+
+#include <sys/time.h>
+#include <stdbool.h>
+
+bool
+linux_sync_file_is_valid(int fd);
+
+int
+linux_sync_file_read_timestamp(int fd, struct timespec *ts);
+
+#endif /* WESTON_LINUX_SYNC_FILE_H */

libweston/meson.build

@@ -433,6 +433,7 @@ if get_option('renderer-gl')
 
 	srcs_renderer_gl = [
 		'gl-renderer.c',
+		'linux-sync-file.c',
 		'vertex-clipping.c',
 		'../shared/matrix.c',
 		linux_dmabuf_unstable_v1_protocol_c,