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1 | /* |
2 | * ring_buffer_vfs.c | |
3 | * | |
4 | * Copyright (C) 2009-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | * | |
6 | * Ring Buffer VFS file operations. | |
7 | * | |
8 | * Dual LGPL v2.1/GPL v2 license. | |
9 | */ | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/fs.h> | |
13 | #include <linux/compat.h> | |
14 | ||
15 | #include "../../wrapper/ringbuffer/backend.h" | |
16 | #include "../../wrapper/ringbuffer/frontend.h" | |
17 | #include "../../wrapper/ringbuffer/vfs.h" | |
18 | #include "../../wrapper/poll.h" | |
19 | ||
20 | static int put_ulong(unsigned long val, unsigned long arg) | |
21 | { | |
22 | return put_user(val, (unsigned long __user *)arg); | |
23 | } | |
24 | ||
25 | #ifdef CONFIG_COMPAT | |
26 | static int compat_put_ulong(compat_ulong_t val, unsigned long arg) | |
27 | { | |
28 | return put_user(val, (compat_ulong_t __user *)compat_ptr(arg)); | |
29 | } | |
30 | #endif | |
31 | ||
32 | /** | |
33 | * lib_ring_buffer_open - ring buffer open file operation | |
34 | * @inode: opened inode | |
35 | * @file: opened file | |
36 | * | |
37 | * Open implementation. Makes sure only one open instance of a buffer is | |
38 | * done at a given moment. | |
39 | */ | |
40 | int lib_ring_buffer_open(struct inode *inode, struct file *file) | |
41 | { | |
42 | struct lib_ring_buffer *buf = inode->i_private; | |
43 | int ret; | |
44 | ||
45 | ret = lib_ring_buffer_open_read(buf); | |
46 | if (ret) | |
47 | return ret; | |
48 | ||
49 | file->private_data = buf; | |
50 | ret = nonseekable_open(inode, file); | |
51 | if (ret) | |
52 | goto release_read; | |
53 | return 0; | |
54 | ||
55 | release_read: | |
56 | lib_ring_buffer_release_read(buf); | |
57 | return ret; | |
58 | } | |
59 | ||
60 | /** | |
61 | * lib_ring_buffer_release - ring buffer release file operation | |
62 | * @inode: opened inode | |
63 | * @file: opened file | |
64 | * | |
65 | * Release implementation. | |
66 | */ | |
67 | int lib_ring_buffer_release(struct inode *inode, struct file *file) | |
68 | { | |
69 | struct lib_ring_buffer *buf = file->private_data; | |
70 | ||
71 | lib_ring_buffer_release_read(buf); | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
76 | /** | |
77 | * lib_ring_buffer_poll - ring buffer poll file operation | |
78 | * @filp: the file | |
79 | * @wait: poll table | |
80 | * | |
81 | * Poll implementation. | |
82 | */ | |
83 | unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait) | |
84 | { | |
85 | unsigned int mask = 0; | |
86 | struct lib_ring_buffer *buf = filp->private_data; | |
87 | struct channel *chan = buf->backend.chan; | |
88 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
89 | int finalized; | |
90 | ||
91 | if (filp->f_mode & FMODE_READ) { | |
92 | poll_wait_set_exclusive(wait); | |
93 | poll_wait(filp, &buf->read_wait, wait); | |
94 | ||
95 | finalized = lib_ring_buffer_is_finalized(config, buf); | |
96 | /* | |
97 | * lib_ring_buffer_is_finalized() contains a smp_rmb() ordering | |
98 | * finalized load before offsets loads. | |
99 | */ | |
100 | WARN_ON(atomic_long_read(&buf->active_readers) != 1); | |
101 | retry: | |
102 | if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), chan) | |
103 | - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), chan) | |
104 | == 0) { | |
105 | if (finalized) | |
106 | return POLLHUP; | |
107 | else { | |
108 | /* | |
109 | * The memory barriers | |
110 | * __wait_event()/wake_up_interruptible() take | |
111 | * care of "raw_spin_is_locked" memory ordering. | |
112 | */ | |
113 | if (raw_spin_is_locked(&buf->raw_tick_nohz_spinlock)) | |
114 | goto retry; | |
115 | else | |
116 | return 0; | |
117 | } | |
118 | } else { | |
119 | if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), | |
120 | chan) | |
121 | - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), | |
122 | chan) | |
123 | >= chan->backend.buf_size) | |
124 | return POLLPRI | POLLRDBAND; | |
125 | else | |
126 | return POLLIN | POLLRDNORM; | |
127 | } | |
128 | } | |
129 | return mask; | |
130 | } | |
131 | ||
132 | /** | |
133 | * lib_ring_buffer_ioctl - control ring buffer reader synchronization | |
134 | * | |
135 | * @filp: the file | |
136 | * @cmd: the command | |
137 | * @arg: command arg | |
138 | * | |
139 | * This ioctl implements commands necessary for producer/consumer | |
140 | * and flight recorder reader interaction : | |
141 | * RING_BUFFER_GET_NEXT_SUBBUF | |
142 | * Get the next sub-buffer that can be read. It never blocks. | |
143 | * RING_BUFFER_PUT_NEXT_SUBBUF | |
144 | * Release the currently read sub-buffer. | |
145 | * RING_BUFFER_GET_SUBBUF_SIZE | |
146 | * returns the size of the current sub-buffer. | |
147 | * RING_BUFFER_GET_MAX_SUBBUF_SIZE | |
148 | * returns the maximum size for sub-buffers. | |
149 | * RING_BUFFER_GET_NUM_SUBBUF | |
150 | * returns the number of reader-visible sub-buffers in the per cpu | |
151 | * channel (for mmap). | |
152 | * RING_BUFFER_GET_MMAP_READ_OFFSET | |
153 | * returns the offset of the subbuffer belonging to the reader. | |
154 | * Should only be used for mmap clients. | |
155 | */ | |
156 | long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
157 | { | |
158 | struct lib_ring_buffer *buf = filp->private_data; | |
159 | struct channel *chan = buf->backend.chan; | |
160 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
161 | ||
162 | switch (cmd) { | |
163 | case RING_BUFFER_SNAPSHOT: | |
164 | return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot, | |
165 | &buf->prod_snapshot); | |
166 | case RING_BUFFER_SNAPSHOT_GET_CONSUMED: | |
167 | return put_ulong(buf->cons_snapshot, arg); | |
168 | case RING_BUFFER_SNAPSHOT_GET_PRODUCED: | |
169 | return put_ulong(buf->prod_snapshot, arg); | |
170 | case RING_BUFFER_GET_SUBBUF: | |
171 | { | |
172 | unsigned long uconsume; | |
173 | long ret; | |
174 | ||
175 | ret = get_user(uconsume, (unsigned long __user *) arg); | |
176 | if (ret) | |
177 | return ret; /* will return -EFAULT */ | |
178 | ret = lib_ring_buffer_get_subbuf(buf, uconsume); | |
179 | if (!ret) { | |
180 | /* Set file position to zero at each successful "get" */ | |
181 | filp->f_pos = 0; | |
182 | } | |
183 | return ret; | |
184 | } | |
185 | case RING_BUFFER_PUT_SUBBUF: | |
186 | lib_ring_buffer_put_subbuf(buf); | |
187 | return 0; | |
188 | ||
189 | case RING_BUFFER_GET_NEXT_SUBBUF: | |
190 | { | |
191 | long ret; | |
192 | ||
193 | ret = lib_ring_buffer_get_next_subbuf(buf); | |
194 | if (!ret) { | |
195 | /* Set file position to zero at each successful "get" */ | |
196 | filp->f_pos = 0; | |
197 | } | |
198 | return ret; | |
199 | } | |
200 | case RING_BUFFER_PUT_NEXT_SUBBUF: | |
201 | lib_ring_buffer_put_next_subbuf(buf); | |
202 | return 0; | |
203 | case RING_BUFFER_GET_SUBBUF_SIZE: | |
204 | return put_ulong(lib_ring_buffer_get_read_data_size(config, buf), | |
205 | arg); | |
206 | case RING_BUFFER_GET_PADDED_SUBBUF_SIZE: | |
207 | { | |
208 | unsigned long size; | |
209 | ||
210 | size = lib_ring_buffer_get_read_data_size(config, buf); | |
211 | size = PAGE_ALIGN(size); | |
212 | return put_ulong(size, arg); | |
213 | } | |
214 | case RING_BUFFER_GET_MAX_SUBBUF_SIZE: | |
215 | return put_ulong(chan->backend.subbuf_size, arg); | |
216 | case RING_BUFFER_GET_MMAP_LEN: | |
217 | { | |
218 | unsigned long mmap_buf_len; | |
219 | ||
220 | if (config->output != RING_BUFFER_MMAP) | |
221 | return -EINVAL; | |
222 | mmap_buf_len = chan->backend.buf_size; | |
223 | if (chan->backend.extra_reader_sb) | |
224 | mmap_buf_len += chan->backend.subbuf_size; | |
225 | if (mmap_buf_len > INT_MAX) | |
226 | return -EFBIG; | |
227 | return put_ulong(mmap_buf_len, arg); | |
228 | } | |
229 | case RING_BUFFER_GET_MMAP_READ_OFFSET: | |
230 | { | |
231 | unsigned long sb_bindex; | |
232 | ||
233 | if (config->output != RING_BUFFER_MMAP) | |
234 | return -EINVAL; | |
235 | sb_bindex = subbuffer_id_get_index(config, | |
236 | buf->backend.buf_rsb.id); | |
237 | return put_ulong(buf->backend.array[sb_bindex]->mmap_offset, | |
238 | arg); | |
239 | } | |
240 | default: | |
241 | return -ENOIOCTLCMD; | |
242 | } | |
243 | } | |
244 | ||
245 | #ifdef CONFIG_COMPAT | |
246 | long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd, | |
247 | unsigned long arg) | |
248 | { | |
249 | struct lib_ring_buffer *buf = filp->private_data; | |
250 | struct channel *chan = buf->backend.chan; | |
251 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
252 | ||
253 | switch (cmd) { | |
254 | case RING_BUFFER_SNAPSHOT: | |
255 | return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot, | |
256 | &buf->prod_snapshot); | |
257 | case RING_BUFFER_SNAPSHOT_GET_CONSUMED: | |
258 | return compat_put_ulong(buf->cons_snapshot, arg); | |
259 | case RING_BUFFER_SNAPSHOT_GET_PRODUCED: | |
260 | return compat_put_ulong(buf->prod_snapshot, arg); | |
261 | case RING_BUFFER_GET_SUBBUF: | |
262 | { | |
263 | __u32 uconsume; | |
264 | unsigned long consume; | |
265 | long ret; | |
266 | ||
267 | ret = get_user(uconsume, (__u32 __user *) arg); | |
268 | if (ret) | |
269 | return ret; /* will return -EFAULT */ | |
270 | consume = buf->cons_snapshot; | |
271 | consume &= ~0xFFFFFFFFL; | |
272 | consume |= uconsume; | |
273 | ret = lib_ring_buffer_get_subbuf(buf, consume); | |
274 | if (!ret) { | |
275 | /* Set file position to zero at each successful "get" */ | |
276 | filp->f_pos = 0; | |
277 | } | |
278 | return ret; | |
279 | } | |
280 | case RING_BUFFER_PUT_SUBBUF: | |
281 | lib_ring_buffer_put_subbuf(buf); | |
282 | return 0; | |
283 | ||
284 | case RING_BUFFER_GET_NEXT_SUBBUF: | |
285 | { | |
286 | long ret; | |
287 | ||
288 | ret = lib_ring_buffer_get_next_subbuf(buf); | |
289 | if (!ret) { | |
290 | /* Set file position to zero at each successful "get" */ | |
291 | filp->f_pos = 0; | |
292 | } | |
293 | return ret; | |
294 | } | |
295 | case RING_BUFFER_PUT_NEXT_SUBBUF: | |
296 | lib_ring_buffer_put_next_subbuf(buf); | |
297 | return 0; | |
298 | case RING_BUFFER_GET_SUBBUF_SIZE: | |
299 | { | |
300 | unsigned long data_size; | |
301 | ||
302 | data_size = lib_ring_buffer_get_read_data_size(config, buf); | |
303 | if (data_size > UINT_MAX) | |
304 | return -EFBIG; | |
305 | return put_ulong(data_size, arg); | |
306 | } | |
307 | case RING_BUFFER_GET_PADDED_SUBBUF_SIZE: | |
308 | { | |
309 | unsigned long size; | |
310 | ||
311 | size = lib_ring_buffer_get_read_data_size(config, buf); | |
312 | size = PAGE_ALIGN(size); | |
313 | if (size > UINT_MAX) | |
314 | return -EFBIG; | |
315 | return put_ulong(size, arg); | |
316 | } | |
317 | case RING_BUFFER_GET_MAX_SUBBUF_SIZE: | |
318 | if (chan->backend.subbuf_size > UINT_MAX) | |
319 | return -EFBIG; | |
320 | return put_ulong(chan->backend.subbuf_size, arg); | |
321 | case RING_BUFFER_GET_MMAP_LEN: | |
322 | { | |
323 | unsigned long mmap_buf_len; | |
324 | ||
325 | if (config->output != RING_BUFFER_MMAP) | |
326 | return -EINVAL; | |
327 | mmap_buf_len = chan->backend.buf_size; | |
328 | if (chan->backend.extra_reader_sb) | |
329 | mmap_buf_len += chan->backend.subbuf_size; | |
330 | if (mmap_buf_len > UINT_MAX) | |
331 | return -EFBIG; | |
332 | return put_ulong(mmap_buf_len, arg); | |
333 | } | |
334 | case RING_BUFFER_GET_MMAP_READ_OFFSET: | |
335 | { | |
336 | unsigned long sb_bindex, read_offset; | |
337 | ||
338 | if (config->output != RING_BUFFER_MMAP) | |
339 | return -EINVAL; | |
340 | sb_bindex = subbuffer_id_get_index(config, | |
341 | buf->backend.buf_rsb.id); | |
342 | read_offset = buf->backend.array[sb_bindex]->mmap_offset; | |
343 | if (read_offset > UINT_MAX) | |
344 | return -EINVAL; | |
345 | return put_ulong(read_offset, arg); | |
346 | } | |
347 | default: | |
348 | return -ENOIOCTLCMD; | |
349 | } | |
350 | } | |
351 | #endif | |
352 | ||
353 | const struct file_operations lib_ring_buffer_file_operations = { | |
354 | .open = lib_ring_buffer_open, | |
355 | .release = lib_ring_buffer_release, | |
356 | .poll = lib_ring_buffer_poll, | |
357 | .splice_read = lib_ring_buffer_splice_read, | |
358 | .mmap = lib_ring_buffer_mmap, | |
359 | .unlocked_ioctl = lib_ring_buffer_ioctl, | |
360 | .llseek = lib_ring_buffer_no_llseek, | |
361 | #ifdef CONFIG_COMPAT | |
362 | .compat_ioctl = lib_ring_buffer_compat_ioctl, | |
363 | #endif | |
364 | }; | |
365 | EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations); | |
366 | ||
367 | MODULE_LICENSE("GPL and additional rights"); | |
368 | MODULE_AUTHOR("Mathieu Desnoyers"); | |
369 | MODULE_DESCRIPTION("Ring Buffer Library VFS"); |