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1 | /* |
2 | * linux/include/linux/relayfs_fs.h | |
3 | * | |
4 | * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp | |
5 | * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com) | |
6 | * | |
7 | * RelayFS definitions and declarations | |
8 | */ | |
9 | ||
10 | #ifndef _LINUX_RELAYFS_FS_H | |
11 | #define _LINUX_RELAYFS_FS_H | |
12 | ||
13 | #include <linux/config.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/wait.h> | |
17 | #include <linux/list.h> | |
18 | #include <linux/fs.h> | |
19 | #include <linux/poll.h> | |
20 | #include <linux/kref.h> | |
21 | ||
22 | /* | |
fd30fc32 | 23 | * Tracks changes to rchan/rchan_buf structs |
e82894f8 | 24 | */ |
fd30fc32 | 25 | #define RELAYFS_CHANNEL_VERSION 6 |
e82894f8 TZ |
26 | |
27 | /* | |
28 | * Per-cpu relay channel buffer | |
29 | */ | |
30 | struct rchan_buf | |
31 | { | |
32 | void *start; /* start of channel buffer */ | |
33 | void *data; /* start of current sub-buffer */ | |
34 | size_t offset; /* current offset into sub-buffer */ | |
35 | size_t subbufs_produced; /* count of sub-buffers produced */ | |
36 | size_t subbufs_consumed; /* count of sub-buffers consumed */ | |
37 | struct rchan *chan; /* associated channel */ | |
38 | wait_queue_head_t read_wait; /* reader wait queue */ | |
39 | struct work_struct wake_readers; /* reader wake-up work struct */ | |
40 | struct dentry *dentry; /* channel file dentry */ | |
41 | struct kref kref; /* channel buffer refcount */ | |
42 | struct page **page_array; /* array of current buffer pages */ | |
43 | unsigned int page_count; /* number of current buffer pages */ | |
44 | unsigned int finalized; /* buffer has been finalized */ | |
45 | size_t *padding; /* padding counts per sub-buffer */ | |
46 | size_t prev_padding; /* temporary variable */ | |
47 | size_t bytes_consumed; /* bytes consumed in cur read subbuf */ | |
48 | unsigned int cpu; /* this buf's cpu */ | |
49 | } ____cacheline_aligned; | |
50 | ||
51 | /* | |
52 | * Relay channel data structure | |
53 | */ | |
54 | struct rchan | |
55 | { | |
56 | u32 version; /* the version of this struct */ | |
57 | size_t subbuf_size; /* sub-buffer size */ | |
58 | size_t n_subbufs; /* number of sub-buffers per buffer */ | |
59 | size_t alloc_size; /* total buffer size allocated */ | |
60 | struct rchan_callbacks *cb; /* client callbacks */ | |
61 | struct kref kref; /* channel refcount */ | |
62 | void *private_data; /* for user-defined data */ | |
fd30fc32 | 63 | size_t last_toobig; /* tried to log event > subbuf size */ |
e82894f8 TZ |
64 | struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */ |
65 | }; | |
66 | ||
e82894f8 TZ |
67 | /* |
68 | * Relay channel client callbacks | |
69 | */ | |
70 | struct rchan_callbacks | |
71 | { | |
72 | /* | |
73 | * subbuf_start - called on buffer-switch to a new sub-buffer | |
74 | * @buf: the channel buffer containing the new sub-buffer | |
75 | * @subbuf: the start of the new sub-buffer | |
76 | * @prev_subbuf: the start of the previous sub-buffer | |
77 | * @prev_padding: unused space at the end of previous sub-buffer | |
78 | * | |
79 | * The client should return 1 to continue logging, 0 to stop | |
80 | * logging. | |
81 | * | |
82 | * NOTE: subbuf_start will also be invoked when the buffer is | |
83 | * created, so that the first sub-buffer can be initialized | |
84 | * if necessary. In this case, prev_subbuf will be NULL. | |
85 | * | |
86 | * NOTE: the client can reserve bytes at the beginning of the new | |
87 | * sub-buffer by calling subbuf_start_reserve() in this callback. | |
88 | */ | |
89 | int (*subbuf_start) (struct rchan_buf *buf, | |
90 | void *subbuf, | |
91 | void *prev_subbuf, | |
92 | size_t prev_padding); | |
93 | ||
94 | /* | |
95 | * buf_mapped - relayfs buffer mmap notification | |
96 | * @buf: the channel buffer | |
97 | * @filp: relayfs file pointer | |
98 | * | |
99 | * Called when a relayfs file is successfully mmapped | |
100 | */ | |
101 | void (*buf_mapped)(struct rchan_buf *buf, | |
102 | struct file *filp); | |
103 | ||
104 | /* | |
105 | * buf_unmapped - relayfs buffer unmap notification | |
106 | * @buf: the channel buffer | |
107 | * @filp: relayfs file pointer | |
108 | * | |
109 | * Called when a relayfs file is successfully unmapped | |
110 | */ | |
111 | void (*buf_unmapped)(struct rchan_buf *buf, | |
112 | struct file *filp); | |
08c541a7 TZ |
113 | /* |
114 | * create_buf_file - create file to represent a relayfs channel buffer | |
115 | * @filename: the name of the file to create | |
116 | * @parent: the parent of the file to create | |
117 | * @mode: the mode of the file to create | |
118 | * @buf: the channel buffer | |
e6c08367 | 119 | * @is_global: outparam - set non-zero if the buffer should be global |
08c541a7 TZ |
120 | * |
121 | * Called during relay_open(), once for each per-cpu buffer, | |
122 | * to allow the client to create a file to be used to | |
123 | * represent the corresponding channel buffer. If the file is | |
124 | * created outside of relayfs, the parent must also exist in | |
125 | * that filesystem. | |
126 | * | |
127 | * The callback should return the dentry of the file created | |
128 | * to represent the relay buffer. | |
129 | * | |
e6c08367 TZ |
130 | * Setting the is_global outparam to a non-zero value will |
131 | * cause relay_open() to create a single global buffer rather | |
132 | * than the default set of per-cpu buffers. | |
133 | * | |
08c541a7 TZ |
134 | * See Documentation/filesystems/relayfs.txt for more info. |
135 | */ | |
136 | struct dentry *(*create_buf_file)(const char *filename, | |
137 | struct dentry *parent, | |
138 | int mode, | |
e6c08367 TZ |
139 | struct rchan_buf *buf, |
140 | int *is_global); | |
08c541a7 TZ |
141 | |
142 | /* | |
143 | * remove_buf_file - remove file representing a relayfs channel buffer | |
144 | * @dentry: the dentry of the file to remove | |
145 | * | |
146 | * Called during relay_close(), once for each per-cpu buffer, | |
147 | * to allow the client to remove a file used to represent a | |
148 | * channel buffer. | |
149 | * | |
150 | * The callback should return 0 if successful, negative if not. | |
151 | */ | |
152 | int (*remove_buf_file)(struct dentry *dentry); | |
e82894f8 TZ |
153 | }; |
154 | ||
155 | /* | |
156 | * relayfs kernel API, fs/relayfs/relay.c | |
157 | */ | |
158 | ||
159 | struct rchan *relay_open(const char *base_filename, | |
160 | struct dentry *parent, | |
161 | size_t subbuf_size, | |
162 | size_t n_subbufs, | |
163 | struct rchan_callbacks *cb); | |
164 | extern void relay_close(struct rchan *chan); | |
165 | extern void relay_flush(struct rchan *chan); | |
166 | extern void relay_subbufs_consumed(struct rchan *chan, | |
167 | unsigned int cpu, | |
168 | size_t consumed); | |
169 | extern void relay_reset(struct rchan *chan); | |
170 | extern int relay_buf_full(struct rchan_buf *buf); | |
171 | ||
172 | extern size_t relay_switch_subbuf(struct rchan_buf *buf, | |
173 | size_t length); | |
174 | extern struct dentry *relayfs_create_dir(const char *name, | |
175 | struct dentry *parent); | |
176 | extern int relayfs_remove_dir(struct dentry *dentry); | |
907f2c77 TZ |
177 | extern struct dentry *relayfs_create_file(const char *name, |
178 | struct dentry *parent, | |
179 | int mode, | |
180 | struct file_operations *fops, | |
181 | void *data); | |
74317337 | 182 | extern int relayfs_remove_file(struct dentry *dentry); |
e82894f8 TZ |
183 | |
184 | /** | |
185 | * relay_write - write data into the channel | |
186 | * @chan: relay channel | |
187 | * @data: data to be written | |
188 | * @length: number of bytes to write | |
189 | * | |
190 | * Writes data into the current cpu's channel buffer. | |
191 | * | |
192 | * Protects the buffer by disabling interrupts. Use this | |
193 | * if you might be logging from interrupt context. Try | |
194 | * __relay_write() if you know you won't be logging from | |
195 | * interrupt context. | |
196 | */ | |
197 | static inline void relay_write(struct rchan *chan, | |
198 | const void *data, | |
199 | size_t length) | |
200 | { | |
201 | unsigned long flags; | |
202 | struct rchan_buf *buf; | |
203 | ||
204 | local_irq_save(flags); | |
205 | buf = chan->buf[smp_processor_id()]; | |
206 | if (unlikely(buf->offset + length > chan->subbuf_size)) | |
207 | length = relay_switch_subbuf(buf, length); | |
208 | memcpy(buf->data + buf->offset, data, length); | |
209 | buf->offset += length; | |
210 | local_irq_restore(flags); | |
211 | } | |
212 | ||
213 | /** | |
214 | * __relay_write - write data into the channel | |
215 | * @chan: relay channel | |
216 | * @data: data to be written | |
217 | * @length: number of bytes to write | |
218 | * | |
219 | * Writes data into the current cpu's channel buffer. | |
220 | * | |
221 | * Protects the buffer by disabling preemption. Use | |
222 | * relay_write() if you might be logging from interrupt | |
223 | * context. | |
224 | */ | |
225 | static inline void __relay_write(struct rchan *chan, | |
226 | const void *data, | |
227 | size_t length) | |
228 | { | |
229 | struct rchan_buf *buf; | |
230 | ||
231 | buf = chan->buf[get_cpu()]; | |
232 | if (unlikely(buf->offset + length > buf->chan->subbuf_size)) | |
233 | length = relay_switch_subbuf(buf, length); | |
234 | memcpy(buf->data + buf->offset, data, length); | |
235 | buf->offset += length; | |
236 | put_cpu(); | |
237 | } | |
238 | ||
239 | /** | |
240 | * relay_reserve - reserve slot in channel buffer | |
241 | * @chan: relay channel | |
242 | * @length: number of bytes to reserve | |
243 | * | |
244 | * Returns pointer to reserved slot, NULL if full. | |
245 | * | |
246 | * Reserves a slot in the current cpu's channel buffer. | |
247 | * Does not protect the buffer at all - caller must provide | |
248 | * appropriate synchronization. | |
249 | */ | |
250 | static inline void *relay_reserve(struct rchan *chan, size_t length) | |
251 | { | |
252 | void *reserved; | |
253 | struct rchan_buf *buf = chan->buf[smp_processor_id()]; | |
254 | ||
255 | if (unlikely(buf->offset + length > buf->chan->subbuf_size)) { | |
256 | length = relay_switch_subbuf(buf, length); | |
257 | if (!length) | |
258 | return NULL; | |
259 | } | |
260 | reserved = buf->data + buf->offset; | |
261 | buf->offset += length; | |
262 | ||
263 | return reserved; | |
264 | } | |
265 | ||
266 | /** | |
267 | * subbuf_start_reserve - reserve bytes at the start of a sub-buffer | |
268 | * @buf: relay channel buffer | |
269 | * @length: number of bytes to reserve | |
270 | * | |
271 | * Helper function used to reserve bytes at the beginning of | |
272 | * a sub-buffer in the subbuf_start() callback. | |
273 | */ | |
274 | static inline void subbuf_start_reserve(struct rchan_buf *buf, | |
275 | size_t length) | |
276 | { | |
277 | BUG_ON(length >= buf->chan->subbuf_size - 1); | |
278 | buf->offset = length; | |
279 | } | |
280 | ||
281 | /* | |
761da5c8 | 282 | * exported relay file operations, fs/relayfs/inode.c |
e82894f8 | 283 | */ |
761da5c8 | 284 | extern struct file_operations relay_file_operations; |
e82894f8 TZ |
285 | |
286 | #endif /* _LINUX_RELAYFS_FS_H */ | |
287 |