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b86ff981 JA |
1 | /* |
2 | * linux/include/linux/relay.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 | * CONFIG_RELAY definitions and declarations | |
8 | */ | |
9 | ||
10 | #ifndef _LINUX_RELAY_H | |
11 | #define _LINUX_RELAY_H | |
12 | ||
b86ff981 JA |
13 | #include <linux/types.h> |
14 | #include <linux/sched.h> | |
15 | #include <linux/wait.h> | |
16 | #include <linux/list.h> | |
17 | #include <linux/fs.h> | |
18 | #include <linux/poll.h> | |
19 | #include <linux/kref.h> | |
20 | ||
21 | /* Needs a _much_ better name... */ | |
22 | #define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE) | |
23 | ||
24 | /* | |
25 | * Tracks changes to rchan/rchan_buf structs | |
26 | */ | |
27 | #define RELAYFS_CHANNEL_VERSION 6 | |
28 | ||
29 | /* | |
30 | * Per-cpu relay channel buffer | |
31 | */ | |
32 | struct rchan_buf | |
33 | { | |
34 | void *start; /* start of channel buffer */ | |
35 | void *data; /* start of current sub-buffer */ | |
36 | size_t offset; /* current offset into sub-buffer */ | |
37 | size_t subbufs_produced; /* count of sub-buffers produced */ | |
38 | size_t subbufs_consumed; /* count of sub-buffers consumed */ | |
39 | struct rchan *chan; /* associated channel */ | |
40 | wait_queue_head_t read_wait; /* reader wait queue */ | |
41 | struct work_struct wake_readers; /* reader wake-up work struct */ | |
42 | struct dentry *dentry; /* channel file dentry */ | |
43 | struct kref kref; /* channel buffer refcount */ | |
44 | struct page **page_array; /* array of current buffer pages */ | |
45 | unsigned int page_count; /* number of current buffer pages */ | |
46 | unsigned int finalized; /* buffer has been finalized */ | |
47 | size_t *padding; /* padding counts per sub-buffer */ | |
48 | size_t prev_padding; /* temporary variable */ | |
49 | size_t bytes_consumed; /* bytes consumed in cur read subbuf */ | |
50 | unsigned int cpu; /* this buf's cpu */ | |
51 | } ____cacheline_aligned; | |
52 | ||
53 | /* | |
54 | * Relay channel data structure | |
55 | */ | |
56 | struct rchan | |
57 | { | |
58 | u32 version; /* the version of this struct */ | |
59 | size_t subbuf_size; /* sub-buffer size */ | |
60 | size_t n_subbufs; /* number of sub-buffers per buffer */ | |
61 | size_t alloc_size; /* total buffer size allocated */ | |
62 | struct rchan_callbacks *cb; /* client callbacks */ | |
63 | struct kref kref; /* channel refcount */ | |
64 | void *private_data; /* for user-defined data */ | |
65 | size_t last_toobig; /* tried to log event > subbuf size */ | |
66 | struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */ | |
67 | }; | |
68 | ||
69 | /* | |
70 | * Relay channel client callbacks | |
71 | */ | |
72 | struct rchan_callbacks | |
73 | { | |
74 | /* | |
75 | * subbuf_start - called on buffer-switch to a new sub-buffer | |
76 | * @buf: the channel buffer containing the new sub-buffer | |
77 | * @subbuf: the start of the new sub-buffer | |
78 | * @prev_subbuf: the start of the previous sub-buffer | |
79 | * @prev_padding: unused space at the end of previous sub-buffer | |
80 | * | |
81 | * The client should return 1 to continue logging, 0 to stop | |
82 | * logging. | |
83 | * | |
84 | * NOTE: subbuf_start will also be invoked when the buffer is | |
85 | * created, so that the first sub-buffer can be initialized | |
86 | * if necessary. In this case, prev_subbuf will be NULL. | |
87 | * | |
88 | * NOTE: the client can reserve bytes at the beginning of the new | |
89 | * sub-buffer by calling subbuf_start_reserve() in this callback. | |
90 | */ | |
91 | int (*subbuf_start) (struct rchan_buf *buf, | |
92 | void *subbuf, | |
93 | void *prev_subbuf, | |
94 | size_t prev_padding); | |
95 | ||
96 | /* | |
97 | * buf_mapped - relay buffer mmap notification | |
98 | * @buf: the channel buffer | |
99 | * @filp: relay file pointer | |
100 | * | |
101 | * Called when a relay file is successfully mmapped | |
102 | */ | |
103 | void (*buf_mapped)(struct rchan_buf *buf, | |
104 | struct file *filp); | |
105 | ||
106 | /* | |
107 | * buf_unmapped - relay buffer unmap notification | |
108 | * @buf: the channel buffer | |
109 | * @filp: relay file pointer | |
110 | * | |
111 | * Called when a relay file is successfully unmapped | |
112 | */ | |
113 | void (*buf_unmapped)(struct rchan_buf *buf, | |
114 | struct file *filp); | |
115 | /* | |
116 | * create_buf_file - create file to represent a relay channel buffer | |
117 | * @filename: the name of the file to create | |
118 | * @parent: the parent of the file to create | |
119 | * @mode: the mode of the file to create | |
120 | * @buf: the channel buffer | |
121 | * @is_global: outparam - set non-zero if the buffer should be global | |
122 | * | |
123 | * Called during relay_open(), once for each per-cpu buffer, | |
124 | * to allow the client to create a file to be used to | |
125 | * represent the corresponding channel buffer. If the file is | |
126 | * created outside of relay, the parent must also exist in | |
127 | * that filesystem. | |
128 | * | |
129 | * The callback should return the dentry of the file created | |
130 | * to represent the relay buffer. | |
131 | * | |
132 | * Setting the is_global outparam to a non-zero value will | |
133 | * cause relay_open() to create a single global buffer rather | |
134 | * than the default set of per-cpu buffers. | |
135 | * | |
136 | * See Documentation/filesystems/relayfs.txt for more info. | |
137 | */ | |
138 | struct dentry *(*create_buf_file)(const char *filename, | |
139 | struct dentry *parent, | |
140 | int mode, | |
141 | struct rchan_buf *buf, | |
142 | int *is_global); | |
143 | ||
144 | /* | |
145 | * remove_buf_file - remove file representing a relay channel buffer | |
146 | * @dentry: the dentry of the file to remove | |
147 | * | |
148 | * Called during relay_close(), once for each per-cpu buffer, | |
149 | * to allow the client to remove a file used to represent a | |
150 | * channel buffer. | |
151 | * | |
152 | * The callback should return 0 if successful, negative if not. | |
153 | */ | |
154 | int (*remove_buf_file)(struct dentry *dentry); | |
155 | }; | |
156 | ||
157 | /* | |
158 | * CONFIG_RELAY kernel API, kernel/relay.c | |
159 | */ | |
160 | ||
161 | struct rchan *relay_open(const char *base_filename, | |
162 | struct dentry *parent, | |
163 | size_t subbuf_size, | |
164 | size_t n_subbufs, | |
165 | struct rchan_callbacks *cb); | |
166 | extern void relay_close(struct rchan *chan); | |
167 | extern void relay_flush(struct rchan *chan); | |
168 | extern void relay_subbufs_consumed(struct rchan *chan, | |
169 | unsigned int cpu, | |
170 | size_t consumed); | |
171 | extern void relay_reset(struct rchan *chan); | |
172 | extern int relay_buf_full(struct rchan_buf *buf); | |
173 | ||
174 | extern size_t relay_switch_subbuf(struct rchan_buf *buf, | |
175 | size_t length); | |
176 | ||
177 | /** | |
178 | * relay_write - write data into the channel | |
179 | * @chan: relay channel | |
180 | * @data: data to be written | |
181 | * @length: number of bytes to write | |
182 | * | |
183 | * Writes data into the current cpu's channel buffer. | |
184 | * | |
185 | * Protects the buffer by disabling interrupts. Use this | |
186 | * if you might be logging from interrupt context. Try | |
187 | * __relay_write() if you know you won't be logging from | |
188 | * interrupt context. | |
189 | */ | |
190 | static inline void relay_write(struct rchan *chan, | |
191 | const void *data, | |
192 | size_t length) | |
193 | { | |
194 | unsigned long flags; | |
195 | struct rchan_buf *buf; | |
196 | ||
197 | local_irq_save(flags); | |
198 | buf = chan->buf[smp_processor_id()]; | |
199 | if (unlikely(buf->offset + length > chan->subbuf_size)) | |
200 | length = relay_switch_subbuf(buf, length); | |
201 | memcpy(buf->data + buf->offset, data, length); | |
202 | buf->offset += length; | |
203 | local_irq_restore(flags); | |
204 | } | |
205 | ||
206 | /** | |
207 | * __relay_write - write data into the channel | |
208 | * @chan: relay channel | |
209 | * @data: data to be written | |
210 | * @length: number of bytes to write | |
211 | * | |
212 | * Writes data into the current cpu's channel buffer. | |
213 | * | |
214 | * Protects the buffer by disabling preemption. Use | |
215 | * relay_write() if you might be logging from interrupt | |
216 | * context. | |
217 | */ | |
218 | static inline void __relay_write(struct rchan *chan, | |
219 | const void *data, | |
220 | size_t length) | |
221 | { | |
222 | struct rchan_buf *buf; | |
223 | ||
224 | buf = chan->buf[get_cpu()]; | |
225 | if (unlikely(buf->offset + length > buf->chan->subbuf_size)) | |
226 | length = relay_switch_subbuf(buf, length); | |
227 | memcpy(buf->data + buf->offset, data, length); | |
228 | buf->offset += length; | |
229 | put_cpu(); | |
230 | } | |
231 | ||
232 | /** | |
233 | * relay_reserve - reserve slot in channel buffer | |
234 | * @chan: relay channel | |
235 | * @length: number of bytes to reserve | |
236 | * | |
237 | * Returns pointer to reserved slot, NULL if full. | |
238 | * | |
239 | * Reserves a slot in the current cpu's channel buffer. | |
240 | * Does not protect the buffer at all - caller must provide | |
241 | * appropriate synchronization. | |
242 | */ | |
243 | static inline void *relay_reserve(struct rchan *chan, size_t length) | |
244 | { | |
245 | void *reserved; | |
246 | struct rchan_buf *buf = chan->buf[smp_processor_id()]; | |
247 | ||
248 | if (unlikely(buf->offset + length > buf->chan->subbuf_size)) { | |
249 | length = relay_switch_subbuf(buf, length); | |
250 | if (!length) | |
251 | return NULL; | |
252 | } | |
253 | reserved = buf->data + buf->offset; | |
254 | buf->offset += length; | |
255 | ||
256 | return reserved; | |
257 | } | |
258 | ||
259 | /** | |
260 | * subbuf_start_reserve - reserve bytes at the start of a sub-buffer | |
261 | * @buf: relay channel buffer | |
262 | * @length: number of bytes to reserve | |
263 | * | |
264 | * Helper function used to reserve bytes at the beginning of | |
265 | * a sub-buffer in the subbuf_start() callback. | |
266 | */ | |
267 | static inline void subbuf_start_reserve(struct rchan_buf *buf, | |
268 | size_t length) | |
269 | { | |
270 | BUG_ON(length >= buf->chan->subbuf_size - 1); | |
271 | buf->offset = length; | |
272 | } | |
273 | ||
274 | /* | |
275 | * exported relay file operations, kernel/relay.c | |
276 | */ | |
277 | extern struct file_operations relay_file_operations; | |
278 | ||
279 | #endif /* _LINUX_RELAY_H */ | |
280 |