libsync/sync.c - android-core - Git at Google

 /*
  *  sync.c
  *
  *   Copyright 2012 Google, Inc
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
  *  You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  *  Unless required by applicable law or agreed to in writing, software
  *  distributed under the License is distributed on an "AS IS" BASIS,
  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  */

 #include <errno.h>
 #include <fcntl.h>
 #include <malloc.h>
 #include <poll.h>
 #include <stdatomic.h>
 #include <stdint.h>
 #include <string.h>

 #include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <sys/types.h>

 #include <android/sync.h>

 /* Legacy Sync API */

 struct sync_legacy_merge_data {
  int32_t fd2;
  char name[32];
  int32_t fence;
 };

 /**
  * DOC: SYNC_IOC_MERGE - merge two fences
  *
  * Takes a struct sync_merge_data.  Creates a new fence containing copies of
  * the sync_pts in both the calling fd and sync_merge_data.fd2.  Returns the
  * new fence's fd in sync_merge_data.fence
  *
  * This is the legacy version of the Sync API before the de-stage that happened
  * on Linux kernel 4.7.
  */
 #define SYNC_IOC_LEGACY_MERGE   _IOWR(SYNC_IOC_MAGIC, 1, \
     struct sync_legacy_merge_data)

 /**
  * DOC: SYNC_IOC_LEGACY_FENCE_INFO - get detailed information on a fence
  *
  * Takes a struct sync_fence_info_data with extra space allocated for pt_info.
  * Caller should write the size of the buffer into len.  On return, len is
  * updated to reflect the total size of the sync_fence_info_data including
  * pt_info.
  *
  * pt_info is a buffer containing sync_pt_infos for every sync_pt in the fence.
  * To iterate over the sync_pt_infos, use the sync_pt_info.len field.
  *
  * This is the legacy version of the Sync API before the de-stage that happened
  * on Linux kernel 4.7.
  */
 #define SYNC_IOC_LEGACY_FENCE_INFO  _IOWR(SYNC_IOC_MAGIC, 2,\
     struct sync_fence_info_data)

 /* SW Sync API */

 struct sw_sync_create_fence_data {
   __u32 value;
   char name[32];
   __s32 fence;
 };

 #define SW_SYNC_IOC_MAGIC 'W'
 #define SW_SYNC_IOC_CREATE_FENCE _IOWR(SW_SYNC_IOC_MAGIC, 0, struct sw_sync_create_fence_data)
 #define SW_SYNC_IOC_INC _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)

 // ---------------------------------------------------------------------------
 // Support for caching the sync uapi version.
 //
 // This library supports both legacy (android/staging) uapi and modern
 // (mainline) sync uapi. Library calls first try one uapi, and if that fails,
 // try the other. Since any given kernel only supports one uapi version, after
 // the first successful syscall we know what the kernel supports and can skip
 // trying the other.

 enum uapi_version {
     UAPI_UNKNOWN,
     UAPI_MODERN,
     UAPI_LEGACY
 };
 static atomic_int g_uapi_version = ATOMIC_VAR_INIT(UAPI_UNKNOWN);

 // ---------------------------------------------------------------------------

 int sync_wait(int fd, int timeout)
 {
     struct pollfd fds;
     int ret;

     if (fd < 0) {
         errno = EINVAL;
         return -1;
     }

     fds.fd = fd;
     fds.events = POLLIN;

     do {
         ret = poll(&fds, 1, timeout);
         if (ret > 0) {
             if (fds.revents & (POLLERR | POLLNVAL)) {
                 errno = EINVAL;
                 return -1;
             }
             return 0;
         } else if (ret == 0) {
             errno = ETIME;
             return -1;
         }
     } while (ret == -1 && (errno == EINTR || errno == EAGAIN));

     return ret;
 }

 static int legacy_sync_merge(const char *name, int fd1, int fd2)
 {
     struct sync_legacy_merge_data data;
     int ret;

     data.fd2 = fd2;
     strlcpy(data.name, name, sizeof(data.name));
     ret = ioctl(fd1, SYNC_IOC_LEGACY_MERGE, &data);
     if (ret < 0)
         return ret;
     return data.fence;
 }

 static int modern_sync_merge(const char *name, int fd1, int fd2)
 {
     struct sync_merge_data data;
     int ret;

     data.fd2 = fd2;
     strlcpy(data.name, name, sizeof(data.name));
     data.flags = 0;
     data.pad = 0;

     ret = ioctl(fd1, SYNC_IOC_MERGE, &data);
     if (ret < 0)
         return ret;
     return data.fence;
 }

 int sync_merge(const char *name, int fd1, int fd2)
 {
     int uapi;
     int ret;

     uapi = atomic_load_explicit(&g_uapi_version, memory_order_acquire);

     if (uapi == UAPI_MODERN || uapi == UAPI_UNKNOWN) {
         ret = modern_sync_merge(name, fd1, fd2);
         if (ret >= 0 || errno != ENOTTY) {
             if (ret >= 0 && uapi == UAPI_UNKNOWN) {
                 atomic_store_explicit(&g_uapi_version, UAPI_MODERN,
                                       memory_order_release);
             }
             return ret;
         }
     }

     ret = legacy_sync_merge(name, fd1, fd2);
     if (ret >= 0 && uapi == UAPI_UNKNOWN) {
         atomic_store_explicit(&g_uapi_version, UAPI_LEGACY,
                               memory_order_release);
     }
     return ret;
 }

 static struct sync_fence_info_data *legacy_sync_fence_info(int fd)
 {
     struct sync_fence_info_data *legacy_info;
     struct sync_pt_info *legacy_pt_info;
     int err;

     legacy_info = malloc(4096);
     if (legacy_info == NULL)
         return NULL;

     legacy_info->len = 4096;
     err = ioctl(fd, SYNC_IOC_LEGACY_FENCE_INFO, legacy_info);
     if (err < 0) {
         free(legacy_info);
         return NULL;
     }
     return legacy_info;
 }

 static struct sync_file_info *modern_sync_file_info(int fd)
 {
     struct sync_file_info local_info;
     struct sync_file_info *info;
     int err;

     memset(&local_info, 0, sizeof(local_info));
     err = ioctl(fd, SYNC_IOC_FILE_INFO, &local_info);
     if (err < 0)
         return NULL;

     info = calloc(1, sizeof(struct sync_file_info) +
                   local_info.num_fences * sizeof(struct sync_fence_info));
     if (!info)
         return NULL;

     info->num_fences = local_info.num_fences;
     info->sync_fence_info = (__u64)(uintptr_t)(info + 1);

     err = ioctl(fd, SYNC_IOC_FILE_INFO, info);
     if (err < 0) {
         free(info);
         return NULL;
     }

     return info;
 }

 static struct sync_fence_info_data *sync_file_info_to_legacy_fence_info(
     const struct sync_file_info *info)
 {
     struct sync_fence_info_data *legacy_info;
     struct sync_pt_info *legacy_pt_info;
     const struct sync_fence_info *fence_info = sync_get_fence_info(info);
     const uint32_t num_fences = info->num_fences;

     legacy_info = malloc(4096);
     if (legacy_info == NULL)
         return NULL;
     legacy_info->len = sizeof(*legacy_info) +
                         num_fences * sizeof(struct sync_pt_info);
     strlcpy(legacy_info->name, info->name, sizeof(legacy_info->name));
     legacy_info->status = info->status;

     legacy_pt_info = (struct sync_pt_info *)legacy_info->pt_info;
     for (uint32_t i = 0; i < num_fences; i++) {
         legacy_pt_info[i].len = sizeof(*legacy_pt_info);
         strlcpy(legacy_pt_info[i].obj_name, fence_info[i].obj_name,
                 sizeof(legacy_pt_info->obj_name));
         strlcpy(legacy_pt_info[i].driver_name, fence_info[i].driver_name,
                 sizeof(legacy_pt_info->driver_name));
         legacy_pt_info[i].status = fence_info[i].status;
         legacy_pt_info[i].timestamp_ns = fence_info[i].timestamp_ns;
     }

     return legacy_info;
 }

 static struct sync_file_info* legacy_fence_info_to_sync_file_info(
                                     struct sync_fence_info_data *legacy_info)
 {
     struct sync_file_info *info;
     struct sync_pt_info *pt;
     struct sync_fence_info *fence;
     size_t num_fences;
     int err;

     pt = NULL;
     num_fences = 0;
     while ((pt = sync_pt_info(legacy_info, pt)) != NULL)
         num_fences++;

     info = calloc(1, sizeof(struct sync_file_info) +
                      num_fences * sizeof(struct sync_fence_info));
     if (!info) {
         free(legacy_info);
         return NULL;
     }
     info->sync_fence_info = (__u64)(uintptr_t)(info + 1);

     strlcpy(info->name, legacy_info->name, sizeof(info->name));
     info->status = legacy_info->status;
     info->num_fences = num_fences;

     pt = NULL;
     fence = sync_get_fence_info(info);
     while ((pt = sync_pt_info(legacy_info, pt)) != NULL) {
         strlcpy(fence->obj_name, pt->obj_name, sizeof(fence->obj_name));
         strlcpy(fence->driver_name, pt->driver_name,
                 sizeof(fence->driver_name));
         fence->status = pt->status;
         fence->timestamp_ns = pt->timestamp_ns;
         fence++;
     }

     return info;
 }

 struct sync_fence_info_data *sync_fence_info(int fd)
 {
     struct sync_fence_info_data *legacy_info;
     int uapi;

     uapi = atomic_load_explicit(&g_uapi_version, memory_order_acquire);

     if (uapi == UAPI_LEGACY || uapi == UAPI_UNKNOWN) {
         legacy_info = legacy_sync_fence_info(fd);
         if (legacy_info || errno != ENOTTY) {
             if (legacy_info && uapi == UAPI_UNKNOWN) {
                 atomic_store_explicit(&g_uapi_version, UAPI_LEGACY,
                                       memory_order_release);
             }
             return legacy_info;
         }
     }

     struct sync_file_info* file_info;
     file_info = modern_sync_file_info(fd);
     if (!file_info)
         return NULL;
     if (uapi == UAPI_UNKNOWN) {
         atomic_store_explicit(&g_uapi_version, UAPI_MODERN,
                               memory_order_release);
     }
     legacy_info = sync_file_info_to_legacy_fence_info(file_info);
     sync_file_info_free(file_info);
     return legacy_info;
 }

 struct sync_file_info* sync_file_info(int32_t fd)
 {
     struct sync_file_info *info;
     int uapi;

     uapi = atomic_load_explicit(&g_uapi_version, memory_order_acquire);

     if (uapi == UAPI_MODERN || uapi == UAPI_UNKNOWN) {
         info = modern_sync_file_info(fd);
         if (info || errno != ENOTTY) {
             if (info && uapi == UAPI_UNKNOWN) {
                 atomic_store_explicit(&g_uapi_version, UAPI_MODERN,
                                       memory_order_release);
             }
             return info;
         }
     }

     struct sync_fence_info_data *legacy_info;
     legacy_info = legacy_sync_fence_info(fd);
     if (!legacy_info)
         return NULL;
     if (uapi == UAPI_UNKNOWN) {
         atomic_store_explicit(&g_uapi_version, UAPI_LEGACY,
                               memory_order_release);
     }
     info = legacy_fence_info_to_sync_file_info(legacy_info);
     sync_fence_info_free(legacy_info);
     return info;
 }

 struct sync_pt_info *sync_pt_info(struct sync_fence_info_data *info,
                                   struct sync_pt_info *itr)
 {
     if (itr == NULL)
         itr = (struct sync_pt_info *) info->pt_info;
     else
         itr = (struct sync_pt_info *) ((__u8 *)itr + itr->len);

     if ((__u8 *)itr - (__u8 *)info >= (int)info->len)
         return NULL;

     return itr;
 }

 void sync_fence_info_free(struct sync_fence_info_data *info)
 {
     free(info);
 }

 void sync_file_info_free(struct sync_file_info *info)
 {
     free(info);
 }


 int sw_sync_timeline_create(void)
 {
     int ret;

     ret = open("/sys/kernel/debug/sync/sw_sync", O_RDWR);
     if (ret < 0)
         ret = open("/dev/sw_sync", O_RDWR);

     return ret;
 }

 int sw_sync_timeline_inc(int fd, unsigned count)
 {
     __u32 arg = count;

     return ioctl(fd, SW_SYNC_IOC_INC, &arg);
 }

 int sw_sync_fence_create(int fd, const char *name, unsigned value)
 {
     struct sw_sync_create_fence_data data;
     int err;

     data.value = value;
     strlcpy(data.name, name, sizeof(data.name));

     err = ioctl(fd, SW_SYNC_IOC_CREATE_FENCE, &data);
     if (err < 0)
         return err;

     return data.fence;
 }
	/*
	* sync.c
	*
	* Copyright 2012 Google, Inc
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <errno.h>
	#include <fcntl.h>
	#include <malloc.h>
	#include <poll.h>
	#include <stdatomic.h>
	#include <stdint.h>
	#include <string.h>

	#include <sys/ioctl.h>
	#include <sys/stat.h>
	#include <sys/types.h>

	#include <android/sync.h>

	/* Legacy Sync API */

	struct sync_legacy_merge_data {
	int32_t fd2;
	char name[32];
	int32_t fence;
	};

	/**
	* DOC: SYNC_IOC_MERGE - merge two fences
	*
	* Takes a struct sync_merge_data. Creates a new fence containing copies of
	* the sync_pts in both the calling fd and sync_merge_data.fd2. Returns the
	* new fence's fd in sync_merge_data.fence
	*
	* This is the legacy version of the Sync API before the de-stage that happened
	* on Linux kernel 4.7.
	*/
	#define SYNC_IOC_LEGACY_MERGE _IOWR(SYNC_IOC_MAGIC, 1, \
	struct sync_legacy_merge_data)

	/**
	* DOC: SYNC_IOC_LEGACY_FENCE_INFO - get detailed information on a fence
	*
	* Takes a struct sync_fence_info_data with extra space allocated for pt_info.
	* Caller should write the size of the buffer into len. On return, len is
	* updated to reflect the total size of the sync_fence_info_data including
	* pt_info.
	*
	* pt_info is a buffer containing sync_pt_infos for every sync_pt in the fence.
	* To iterate over the sync_pt_infos, use the sync_pt_info.len field.
	*
	* This is the legacy version of the Sync API before the de-stage that happened
	* on Linux kernel 4.7.
	*/
	#define SYNC_IOC_LEGACY_FENCE_INFO _IOWR(SYNC_IOC_MAGIC, 2,\
	struct sync_fence_info_data)

	/* SW Sync API */

	struct sw_sync_create_fence_data {
	__u32 value;
	char name[32];
	__s32 fence;
	};

	#define SW_SYNC_IOC_MAGIC 'W'
	#define SW_SYNC_IOC_CREATE_FENCE _IOWR(SW_SYNC_IOC_MAGIC, 0, struct sw_sync_create_fence_data)
	#define SW_SYNC_IOC_INC _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)

	// ---------------------------------------------------------------------------
	// Support for caching the sync uapi version.
	//
	// This library supports both legacy (android/staging) uapi and modern
	// (mainline) sync uapi. Library calls first try one uapi, and if that fails,
	// try the other. Since any given kernel only supports one uapi version, after
	// the first successful syscall we know what the kernel supports and can skip
	// trying the other.

	enum uapi_version {
	UAPI_UNKNOWN,
	UAPI_MODERN,
	UAPI_LEGACY
	};
	static atomic_int g_uapi_version = ATOMIC_VAR_INIT(UAPI_UNKNOWN);

	// ---------------------------------------------------------------------------

	int sync_wait(int fd, int timeout)
	{
	struct pollfd fds;
	int ret;

	if (fd < 0) {
	errno = EINVAL;
	return -1;
	}

	fds.fd = fd;
	fds.events = POLLIN;

	do {
	ret = poll(&fds, 1, timeout);
	if (ret > 0) {
	if (fds.revents & (POLLERR \| POLLNVAL)) {
	errno = EINVAL;
	return -1;
	}
	return 0;
	} else if (ret == 0) {
	errno = ETIME;
	return -1;
	}
	} while (ret == -1 && (errno == EINTR \|\| errno == EAGAIN));

	return ret;
	}

	static int legacy_sync_merge(const char *name, int fd1, int fd2)
	{
	struct sync_legacy_merge_data data;
	int ret;

	data.fd2 = fd2;
	strlcpy(data.name, name, sizeof(data.name));
	ret = ioctl(fd1, SYNC_IOC_LEGACY_MERGE, &data);
	if (ret < 0)
	return ret;
	return data.fence;
	}

	static int modern_sync_merge(const char *name, int fd1, int fd2)
	{
	struct sync_merge_data data;
	int ret;

	data.fd2 = fd2;
	strlcpy(data.name, name, sizeof(data.name));
	data.flags = 0;
	data.pad = 0;

	ret = ioctl(fd1, SYNC_IOC_MERGE, &data);
	if (ret < 0)
	return ret;
	return data.fence;
	}

	int sync_merge(const char *name, int fd1, int fd2)
	{
	int uapi;
	int ret;

	uapi = atomic_load_explicit(&g_uapi_version, memory_order_acquire);

	if (uapi == UAPI_MODERN \|\| uapi == UAPI_UNKNOWN) {
	ret = modern_sync_merge(name, fd1, fd2);
	if (ret >= 0 \|\| errno != ENOTTY) {
	if (ret >= 0 && uapi == UAPI_UNKNOWN) {
	atomic_store_explicit(&g_uapi_version, UAPI_MODERN,
	memory_order_release);
	}
	return ret;
	}
	}

	ret = legacy_sync_merge(name, fd1, fd2);
	if (ret >= 0 && uapi == UAPI_UNKNOWN) {
	atomic_store_explicit(&g_uapi_version, UAPI_LEGACY,
	memory_order_release);
	}
	return ret;
	}

	static struct sync_fence_info_data *legacy_sync_fence_info(int fd)
	{
	struct sync_fence_info_data *legacy_info;
	struct sync_pt_info *legacy_pt_info;
	int err;

	legacy_info = malloc(4096);
	if (legacy_info == NULL)
	return NULL;

	legacy_info->len = 4096;
	err = ioctl(fd, SYNC_IOC_LEGACY_FENCE_INFO, legacy_info);
	if (err < 0) {
	free(legacy_info);
	return NULL;
	}
	return legacy_info;
	}

	static struct sync_file_info *modern_sync_file_info(int fd)
	{
	struct sync_file_info local_info;
	struct sync_file_info *info;
	int err;

	memset(&local_info, 0, sizeof(local_info));
	err = ioctl(fd, SYNC_IOC_FILE_INFO, &local_info);
	if (err < 0)
	return NULL;

	info = calloc(1, sizeof(struct sync_file_info) +
	local_info.num_fences * sizeof(struct sync_fence_info));
	if (!info)
	return NULL;

	info->num_fences = local_info.num_fences;
	info->sync_fence_info = (__u64)(uintptr_t)(info + 1);

	err = ioctl(fd, SYNC_IOC_FILE_INFO, info);
	if (err < 0) {
	free(info);
	return NULL;
	}

	return info;
	}

	static struct sync_fence_info_data *sync_file_info_to_legacy_fence_info(
	const struct sync_file_info *info)
	{
	struct sync_fence_info_data *legacy_info;
	struct sync_pt_info *legacy_pt_info;
	const struct sync_fence_info *fence_info = sync_get_fence_info(info);
	const uint32_t num_fences = info->num_fences;

	legacy_info = malloc(4096);
	if (legacy_info == NULL)
	return NULL;
	legacy_info->len = sizeof(*legacy_info) +
	num_fences * sizeof(struct sync_pt_info);
	strlcpy(legacy_info->name, info->name, sizeof(legacy_info->name));
	legacy_info->status = info->status;

	legacy_pt_info = (struct sync_pt_info *)legacy_info->pt_info;
	for (uint32_t i = 0; i < num_fences; i++) {
	legacy_pt_info[i].len = sizeof(*legacy_pt_info);
	strlcpy(legacy_pt_info[i].obj_name, fence_info[i].obj_name,
	sizeof(legacy_pt_info->obj_name));
	strlcpy(legacy_pt_info[i].driver_name, fence_info[i].driver_name,
	sizeof(legacy_pt_info->driver_name));
	legacy_pt_info[i].status = fence_info[i].status;
	legacy_pt_info[i].timestamp_ns = fence_info[i].timestamp_ns;
	}

	return legacy_info;
	}

	static struct sync_file_info* legacy_fence_info_to_sync_file_info(
	struct sync_fence_info_data *legacy_info)
	{
	struct sync_file_info *info;
	struct sync_pt_info *pt;
	struct sync_fence_info *fence;
	size_t num_fences;
	int err;

	pt = NULL;
	num_fences = 0;
	while ((pt = sync_pt_info(legacy_info, pt)) != NULL)
	num_fences++;

	info = calloc(1, sizeof(struct sync_file_info) +
	num_fences * sizeof(struct sync_fence_info));
	if (!info) {
	free(legacy_info);
	return NULL;
	}
	info->sync_fence_info = (__u64)(uintptr_t)(info + 1);

	strlcpy(info->name, legacy_info->name, sizeof(info->name));
	info->status = legacy_info->status;
	info->num_fences = num_fences;

	pt = NULL;
	fence = sync_get_fence_info(info);
	while ((pt = sync_pt_info(legacy_info, pt)) != NULL) {
	strlcpy(fence->obj_name, pt->obj_name, sizeof(fence->obj_name));
	strlcpy(fence->driver_name, pt->driver_name,
	sizeof(fence->driver_name));
	fence->status = pt->status;
	fence->timestamp_ns = pt->timestamp_ns;
	fence++;
	}

	return info;
	}

	struct sync_fence_info_data *sync_fence_info(int fd)
	{
	struct sync_fence_info_data *legacy_info;
	int uapi;

	uapi = atomic_load_explicit(&g_uapi_version, memory_order_acquire);

	if (uapi == UAPI_LEGACY \|\| uapi == UAPI_UNKNOWN) {
	legacy_info = legacy_sync_fence_info(fd);
	if (legacy_info \|\| errno != ENOTTY) {
	if (legacy_info && uapi == UAPI_UNKNOWN) {
	atomic_store_explicit(&g_uapi_version, UAPI_LEGACY,
	memory_order_release);
	}
	return legacy_info;
	}
	}

	struct sync_file_info* file_info;
	file_info = modern_sync_file_info(fd);
	if (!file_info)
	return NULL;
	if (uapi == UAPI_UNKNOWN) {
	atomic_store_explicit(&g_uapi_version, UAPI_MODERN,
	memory_order_release);
	}
	legacy_info = sync_file_info_to_legacy_fence_info(file_info);
	sync_file_info_free(file_info);
	return legacy_info;
	}

	struct sync_file_info* sync_file_info(int32_t fd)
	{
	struct sync_file_info *info;
	int uapi;

	uapi = atomic_load_explicit(&g_uapi_version, memory_order_acquire);

	if (uapi == UAPI_MODERN \|\| uapi == UAPI_UNKNOWN) {
	info = modern_sync_file_info(fd);
	if (info \|\| errno != ENOTTY) {
	if (info && uapi == UAPI_UNKNOWN) {
	atomic_store_explicit(&g_uapi_version, UAPI_MODERN,
	memory_order_release);
	}
	return info;
	}
	}

	struct sync_fence_info_data *legacy_info;
	legacy_info = legacy_sync_fence_info(fd);
	if (!legacy_info)
	return NULL;
	if (uapi == UAPI_UNKNOWN) {
	atomic_store_explicit(&g_uapi_version, UAPI_LEGACY,
	memory_order_release);
	}
	info = legacy_fence_info_to_sync_file_info(legacy_info);
	sync_fence_info_free(legacy_info);
	return info;
	}

	struct sync_pt_info sync_pt_info(struct sync_fence_info_data info,
	struct sync_pt_info *itr)
	{
	if (itr == NULL)
	itr = (struct sync_pt_info *) info->pt_info;
	else
	itr = (struct sync_pt_info ) ((__u8 )itr + itr->len);

	if ((__u8 )itr - (__u8 )info >= (int)info->len)
	return NULL;

	return itr;
	}

	void sync_fence_info_free(struct sync_fence_info_data *info)
	{
	free(info);
	}

	void sync_file_info_free(struct sync_file_info *info)
	{
	free(info);
	}


	int sw_sync_timeline_create(void)
	{
	int ret;

	ret = open("/sys/kernel/debug/sync/sw_sync", O_RDWR);
	if (ret < 0)
	ret = open("/dev/sw_sync", O_RDWR);

	return ret;
	}

	int sw_sync_timeline_inc(int fd, unsigned count)
	{
	__u32 arg = count;

	return ioctl(fd, SW_SYNC_IOC_INC, &arg);
	}

	int sw_sync_fence_create(int fd, const char *name, unsigned value)
	{
	struct sw_sync_create_fence_data data;
	int err;

	data.value = value;
	strlcpy(data.name, name, sizeof(data.name));

	err = ioctl(fd, SW_SYNC_IOC_CREATE_FENCE, &data);
	if (err < 0)
	return err;

	return data.fence;
	}