1 /*
2 * sync abstraction
3 * Copyright 2015-2016 Collabora Ltd.
4 *
5 * Based on the implementation from the Android Open Source Project,
6 *
7 * Copyright 2012 Google, Inc
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a
10 * copy of this software and associated documentation files (the "Software"),
11 * to deal in the Software without restriction, including without limitation
12 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13 * and/or sell copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included in
17 * all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
22 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
23 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
24 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
25 * OTHER DEALINGS IN THE SOFTWARE.
26 */
27
28 #ifndef _LIBSYNC_H
29 #define _LIBSYNC_H
30
31 #include <assert.h>
32 #include <errno.h>
33 #include <stdbool.h>
34 #include <stdint.h>
35 #include <string.h>
36 #include <sys/ioctl.h>
37 #include <sys/poll.h>
38 #include <unistd.h>
39
40 #if defined(__cplusplus)
41 extern "C" {
42 #endif
43
44 #ifdef ANDROID
45 /* On Android, rely on the system's libsync instead of rolling our own
46 * sync_wait() and sync_merge(). This gives us compatibility with pre-4.7
47 * Android kernels.
48 */
49 #include <android/sync.h>
50
51 /**
52 * Check if the fd represents a valid fence-fd.
53 *
54 * The android variant of this debug helper is implemented on top of the
55 * system's libsync for compatibility with pre-4.7 android kernels.
56 */
57 static inline bool
sync_valid_fd(int fd)58 sync_valid_fd(int fd)
59 {
60 /* sync_file_info() only available in SDK 26. */
61 #if ANDROID_API_LEVEL >= 26
62 struct sync_file_info *info = sync_file_info(fd);
63 if (!info)
64 return false;
65 sync_file_info_free(info);
66 #endif
67 return true;
68 }
69 #else
70
71 #ifndef SYNC_IOC_MERGE
72 /* duplicated from linux/sync_file.h to avoid build-time dependency
73 * on new (v4.7) kernel headers. Once distro's are mostly using
74 * something newer than v4.7 drop this and #include <linux/sync_file.h>
75 * instead.
76 */
77 struct sync_merge_data {
78 char name[32];
79 int32_t fd2;
80 int32_t fence;
81 uint32_t flags;
82 uint32_t pad;
83 };
84
85 struct sync_file_info {
86 char name[32];
87 int32_t status;
88 uint32_t flags;
89 uint32_t num_fences;
90 uint32_t pad;
91
92 uint64_t sync_fence_info;
93 };
94
95 #define SYNC_IOC_MAGIC '>'
96 #define SYNC_IOC_MERGE _IOWR(SYNC_IOC_MAGIC, 3, struct sync_merge_data)
97 #define SYNC_IOC_FILE_INFO _IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
98 #endif
99
100
101 static inline int sync_wait(int fd, int timeout)
102 {
103 struct pollfd fds = {0};
104 int ret;
105
106 fds.fd = fd;
107 fds.events = POLLIN;
108
109 do {
110 ret = poll(&fds, 1, timeout);
111 if (ret > 0) {
112 if (fds.revents & (POLLERR | POLLNVAL)) {
113 errno = EINVAL;
114 return -1;
115 }
116 return 0;
117 } else if (ret == 0) {
118 errno = ETIME;
119 return -1;
120 }
121 } while (ret == -1 && (errno == EINTR || errno == EAGAIN));
122
123 return ret;
124 }
125
126 static inline int sync_merge(const char *name, int fd1, int fd2)
127 {
128 struct sync_merge_data data = {0};
129 int ret;
130
131 data.fd2 = fd2;
132 strncpy(data.name, name, sizeof(data.name));
133
134 do {
135 ret = ioctl(fd1, SYNC_IOC_MERGE, &data);
136 } while (ret == -1 && (errno == EINTR || errno == EAGAIN));
137
138 if (ret < 0)
139 return ret;
140
141 return data.fence;
142 }
143
144 /**
145 * Check if the fd represents a valid fence-fd.
146 */
147 static inline bool
148 sync_valid_fd(int fd)
149 {
150 struct sync_file_info info = {{0}};
151 return ioctl(fd, SYNC_IOC_FILE_INFO, &info) >= 0;
152 }
153
154 #endif /* !ANDROID */
155
156 /* accumulate fd2 into fd1. If *fd1 is not a valid fd then dup fd2,
157 * otherwise sync_merge() and close the old *fd1. This can be used
158 * to implement the pattern:
159 *
160 * init()
161 * {
162 * batch.fence_fd = -1;
163 * }
164 *
165 * // does *NOT* take ownership of fd
166 * server_sync(int fd)
167 * {
168 * if (sync_accumulate("foo", &batch.fence_fd, fd)) {
169 * ... error ...
170 * }
171 * }
172 */
sync_accumulate(const char * name,int * fd1,int fd2)173 static inline int sync_accumulate(const char *name, int *fd1, int fd2)
174 {
175 int ret;
176
177 assert(fd2 >= 0);
178
179 if (*fd1 < 0) {
180 *fd1 = dup(fd2);
181 return 0;
182 }
183
184 ret = sync_merge(name, *fd1, fd2);
185 if (ret < 0) {
186 /* leave *fd1 as it is */
187 return ret;
188 }
189
190 close(*fd1);
191 *fd1 = ret;
192
193 return 0;
194 }
195
196 #if defined(__cplusplus)
197 }
198 #endif
199
200 #endif
201