/*
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* sync.c
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*
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* Copyright 2012 Google, Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <malloc.h>
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#include <poll.h>
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#include <stdint.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <linux/sync_file.h>
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#ifndef __cplusplus
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# include <stdatomic.h>
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#else
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# include <atomic>
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# define _Atomic(X) std::atomic< X >
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using namespace std;
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#endif
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#include "rga_sync.h"
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/* Legacy Sync API */
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struct sync_legacy_merge_data {
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int32_t fd2;
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char name[32];
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int32_t fence;
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};
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/**
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* DOC: SYNC_IOC_MERGE - merge two fences
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*
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* Takes a struct sync_merge_data. Creates a new fence containing copies of
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* the sync_pts in both the calling fd and sync_merge_data.fd2. Returns the
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* new fence's fd in sync_merge_data.fence
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*
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* This is the legacy version of the Sync API before the de-stage that happened
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* on Linux kernel 4.7.
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*/
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#define SYNC_IOC_LEGACY_MERGE _IOWR(SYNC_IOC_MAGIC, 1, \
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struct sync_legacy_merge_data)
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// ---------------------------------------------------------------------------
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// Support for caching the sync uapi version.
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//
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// This library supports both legacy (android/staging) uapi and modern
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// (mainline) sync uapi. Library calls first try one uapi, and if that fails,
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// try the other. Since any given kernel only supports one uapi version, after
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// the first successful syscall we know what the kernel supports and can skip
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// trying the other.
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enum uapi_version {
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UAPI_UNKNOWN,
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UAPI_MODERN,
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UAPI_LEGACY
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};
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static atomic_int g_uapi_version = ATOMIC_VAR_INIT(UAPI_UNKNOWN);
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static size_t rga_strlcpy(char *dest, const char *src, size_t size) {
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size_t src_len = strlen(src);
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size_t len = 0;
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if (size) {
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len = src_len >= size ? (size - 1) : src_len;
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// strncpy(dest, src, len);
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memcpy(dest, src, len);
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dest[len] = '\0';
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}
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return src_len;
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}
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/* sync wait */
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int rga_sync_wait(int fd, int timeout)
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{
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struct pollfd fds;
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int ret;
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if (fd < 0) {
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errno = EINVAL;
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return -1;
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}
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fds.fd = fd;
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fds.events = POLLIN;
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do {
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ret = poll(&fds, 1, timeout);
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if (ret > 0) {
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if (fds.revents & (POLLERR | POLLNVAL)) {
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errno = EINVAL;
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return -1;
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}
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return 0;
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} else if (ret == 0) {
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errno = ETIME;
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return -1;
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}
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} while (ret == -1 && (errno == EINTR || errno == EAGAIN));
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return ret;
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}
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/* sync merge */
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static int legacy_sync_merge(const char *name, int fd1, int fd2)
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{
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struct sync_legacy_merge_data data;
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int ret;
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data.fd2 = fd2;
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rga_strlcpy(data.name, name, sizeof(data.name));
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ret = ioctl(fd1, SYNC_IOC_LEGACY_MERGE, &data);
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if (ret < 0)
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return ret;
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return data.fence;
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}
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static int modern_sync_merge(const char *name, int fd1, int fd2)
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{
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struct sync_merge_data data;
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int ret;
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data.fd2 = fd2;
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rga_strlcpy(data.name, name, sizeof(data.name));
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data.flags = 0;
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data.pad = 0;
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ret = ioctl(fd1, SYNC_IOC_MERGE, &data);
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if (ret < 0)
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return ret;
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return data.fence;
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}
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int rga_sync_merge(const char *name, int fd1, int fd2)
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{
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int uapi;
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int ret;
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uapi = atomic_load_explicit(&g_uapi_version, memory_order_acquire);
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if (uapi == UAPI_MODERN || uapi == UAPI_UNKNOWN) {
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ret = modern_sync_merge(name, fd1, fd2);
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if (ret >= 0 || errno != ENOTTY) {
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if (ret >= 0 && uapi == UAPI_UNKNOWN) {
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atomic_store_explicit(&g_uapi_version, (int)UAPI_MODERN,
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memory_order_release);
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}
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return ret;
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}
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}
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ret = legacy_sync_merge(name, fd1, fd2);
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if (ret >= 0 && uapi == UAPI_UNKNOWN) {
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atomic_store_explicit(&g_uapi_version, (int)UAPI_LEGACY,
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memory_order_release);
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}
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return ret;
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}
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