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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 | |
13 | #include <linux/types.h> |
14 | #include <linux/sched.h> |
15 | #include <linux/timer.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 | /* Needs a _much_ better name... */ |
23 | #define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE) |
24 | |
25 | /* |
26 | * Tracks changes to rchan/rchan_buf structs |
27 | */ |
28 | #define RELAYFS_CHANNEL_VERSION 7 |
29 | |
30 | /* |
31 | * Per-cpu relay channel buffer |
32 | */ |
33 | struct rchan_buf |
34 | { |
35 | void *start; /* start of channel buffer */ |
36 | void *data; /* start of current sub-buffer */ |
37 | size_t offset; /* current offset into sub-buffer */ |
38 | size_t subbufs_produced; /* count of sub-buffers produced */ |
39 | size_t subbufs_consumed; /* count of sub-buffers consumed */ |
40 | struct rchan *chan; /* associated channel */ |
41 | wait_queue_head_t read_wait; /* reader wait queue */ |
42 | struct timer_list timer; /* reader wake-up timer */ |
43 | struct dentry *dentry; /* channel file dentry */ |
44 | struct kref kref; /* channel buffer refcount */ |
45 | struct page **page_array; /* array of current buffer pages */ |
46 | unsigned int page_count; /* number of current buffer pages */ |
47 | unsigned int finalized; /* buffer has been finalized */ |
48 | size_t *padding; /* padding counts per sub-buffer */ |
49 | size_t prev_padding; /* temporary variable */ |
50 | size_t bytes_consumed; /* bytes consumed in cur read subbuf */ |
51 | size_t early_bytes; /* bytes consumed before VFS inited */ |
52 | unsigned int cpu; /* this buf's cpu */ |
53 | } ____cacheline_aligned; |
54 | |
55 | /* |
56 | * Relay channel data structure |
57 | */ |
58 | struct rchan |
59 | { |
60 | u32 version; /* the version of this struct */ |
61 | size_t subbuf_size; /* sub-buffer size */ |
62 | size_t n_subbufs; /* number of sub-buffers per buffer */ |
63 | size_t alloc_size; /* total buffer size allocated */ |
64 | struct rchan_callbacks *cb; /* client callbacks */ |
65 | struct kref kref; /* channel refcount */ |
66 | void *private_data; /* for user-defined data */ |
67 | size_t last_toobig; /* tried to log event > subbuf size */ |
68 | struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */ |
69 | int is_global; /* One global buffer ? */ |
70 | struct list_head list; /* for channel list */ |
71 | struct dentry *parent; /* parent dentry passed to open */ |
72 | int has_base_filename; /* has a filename associated? */ |
73 | char base_filename[NAME_MAX]; /* saved base filename */ |
74 | }; |
75 | |
76 | /* |
77 | * Relay channel client callbacks |
78 | */ |
79 | struct rchan_callbacks |
80 | { |
81 | /* |
82 | * subbuf_start - called on buffer-switch to a new sub-buffer |
83 | * @buf: the channel buffer containing the new sub-buffer |
84 | * @subbuf: the start of the new sub-buffer |
85 | * @prev_subbuf: the start of the previous sub-buffer |
86 | * @prev_padding: unused space at the end of previous sub-buffer |
87 | * |
88 | * The client should return 1 to continue logging, 0 to stop |
89 | * logging. |
90 | * |
91 | * NOTE: subbuf_start will also be invoked when the buffer is |
92 | * created, so that the first sub-buffer can be initialized |
93 | * if necessary. In this case, prev_subbuf will be NULL. |
94 | * |
95 | * NOTE: the client can reserve bytes at the beginning of the new |
96 | * sub-buffer by calling subbuf_start_reserve() in this callback. |
97 | */ |
98 | int (*subbuf_start) (struct rchan_buf *buf, |
99 | void *subbuf, |
100 | void *prev_subbuf, |
101 | size_t prev_padding); |
102 | |
103 | /* |
104 | * buf_mapped - relay buffer mmap notification |
105 | * @buf: the channel buffer |
106 | * @filp: relay file pointer |
107 | * |
108 | * Called when a relay file is successfully mmapped |
109 | */ |
110 | void (*buf_mapped)(struct rchan_buf *buf, |
111 | struct file *filp); |
112 | |
113 | /* |
114 | * buf_unmapped - relay buffer unmap notification |
115 | * @buf: the channel buffer |
116 | * @filp: relay file pointer |
117 | * |
118 | * Called when a relay file is successfully unmapped |
119 | */ |
120 | void (*buf_unmapped)(struct rchan_buf *buf, |
121 | struct file *filp); |
122 | /* |
123 | * create_buf_file - create file to represent a relay channel buffer |
124 | * @filename: the name of the file to create |
125 | * @parent: the parent of the file to create |
126 | * @mode: the mode of the file to create |
127 | * @buf: the channel buffer |
128 | * @is_global: outparam - set non-zero if the buffer should be global |
129 | * |
130 | * Called during relay_open(), once for each per-cpu buffer, |
131 | * to allow the client to create a file to be used to |
132 | * represent the corresponding channel buffer. If the file is |
133 | * created outside of relay, the parent must also exist in |
134 | * that filesystem. |
135 | * |
136 | * The callback should return the dentry of the file created |
137 | * to represent the relay buffer. |
138 | * |
139 | * Setting the is_global outparam to a non-zero value will |
140 | * cause relay_open() to create a single global buffer rather |
141 | * than the default set of per-cpu buffers. |
142 | * |
143 | * See Documentation/filesystems/relay.txt for more info. |
144 | */ |
145 | struct dentry *(*create_buf_file)(const char *filename, |
146 | struct dentry *parent, |
147 | int mode, |
148 | struct rchan_buf *buf, |
149 | int *is_global); |
150 | |
151 | /* |
152 | * remove_buf_file - remove file representing a relay channel buffer |
153 | * @dentry: the dentry of the file to remove |
154 | * |
155 | * Called during relay_close(), once for each per-cpu buffer, |
156 | * to allow the client to remove a file used to represent a |
157 | * channel buffer. |
158 | * |
159 | * The callback should return 0 if successful, negative if not. |
160 | */ |
161 | int (*remove_buf_file)(struct dentry *dentry); |
162 | }; |
163 | |
164 | /* |
165 | * CONFIG_RELAY kernel API, kernel/relay.c |
166 | */ |
167 | |
168 | struct rchan *relay_open(const char *base_filename, |
169 | struct dentry *parent, |
170 | size_t subbuf_size, |
171 | size_t n_subbufs, |
172 | struct rchan_callbacks *cb, |
173 | void *private_data); |
174 | extern int relay_late_setup_files(struct rchan *chan, |
175 | const char *base_filename, |
176 | struct dentry *parent); |
177 | extern void relay_close(struct rchan *chan); |
178 | extern void relay_flush(struct rchan *chan); |
179 | extern void relay_subbufs_consumed(struct rchan *chan, |
180 | unsigned int cpu, |
181 | size_t consumed); |
182 | extern void relay_reset(struct rchan *chan); |
183 | extern int relay_buf_full(struct rchan_buf *buf); |
184 | |
185 | extern size_t relay_switch_subbuf(struct rchan_buf *buf, |
186 | size_t length); |
187 | |
188 | /** |
189 | * relay_write - write data into the channel |
190 | * @chan: relay channel |
191 | * @data: data to be written |
192 | * @length: number of bytes to write |
193 | * |
194 | * Writes data into the current cpu's channel buffer. |
195 | * |
196 | * Protects the buffer by disabling interrupts. Use this |
197 | * if you might be logging from interrupt context. Try |
198 | * __relay_write() if you know you won't be logging from |
199 | * interrupt context. |
200 | */ |
201 | static inline void relay_write(struct rchan *chan, |
202 | const void *data, |
203 | size_t length) |
204 | { |
205 | unsigned long flags; |
206 | struct rchan_buf *buf; |
207 | |
208 | local_irq_save(flags); |
209 | buf = chan->buf[smp_processor_id()]; |
210 | if (unlikely(buf->offset + length > chan->subbuf_size)) |
211 | length = relay_switch_subbuf(buf, length); |
212 | memcpy(buf->data + buf->offset, data, length); |
213 | buf->offset += length; |
214 | local_irq_restore(flags); |
215 | } |
216 | |
217 | /** |
218 | * __relay_write - write data into the channel |
219 | * @chan: relay channel |
220 | * @data: data to be written |
221 | * @length: number of bytes to write |
222 | * |
223 | * Writes data into the current cpu's channel buffer. |
224 | * |
225 | * Protects the buffer by disabling preemption. Use |
226 | * relay_write() if you might be logging from interrupt |
227 | * context. |
228 | */ |
229 | static inline void __relay_write(struct rchan *chan, |
230 | const void *data, |
231 | size_t length) |
232 | { |
233 | struct rchan_buf *buf; |
234 | |
235 | buf = chan->buf[get_cpu()]; |
236 | if (unlikely(buf->offset + length > buf->chan->subbuf_size)) |
237 | length = relay_switch_subbuf(buf, length); |
238 | memcpy(buf->data + buf->offset, data, length); |
239 | buf->offset += length; |
240 | put_cpu(); |
241 | } |
242 | |
243 | /** |
244 | * relay_reserve - reserve slot in channel buffer |
245 | * @chan: relay channel |
246 | * @length: number of bytes to reserve |
247 | * |
248 | * Returns pointer to reserved slot, NULL if full. |
249 | * |
250 | * Reserves a slot in the current cpu's channel buffer. |
251 | * Does not protect the buffer at all - caller must provide |
252 | * appropriate synchronization. |
253 | */ |
254 | static inline void *relay_reserve(struct rchan *chan, size_t length) |
255 | { |
256 | void *reserved; |
257 | struct rchan_buf *buf = chan->buf[smp_processor_id()]; |
258 | |
259 | if (unlikely(buf->offset + length > buf->chan->subbuf_size)) { |
260 | length = relay_switch_subbuf(buf, length); |
261 | if (!length) |
262 | return NULL; |
263 | } |
264 | reserved = buf->data + buf->offset; |
265 | buf->offset += length; |
266 | |
267 | return reserved; |
268 | } |
269 | |
270 | /** |
271 | * subbuf_start_reserve - reserve bytes at the start of a sub-buffer |
272 | * @buf: relay channel buffer |
273 | * @length: number of bytes to reserve |
274 | * |
275 | * Helper function used to reserve bytes at the beginning of |
276 | * a sub-buffer in the subbuf_start() callback. |
277 | */ |
278 | static inline void subbuf_start_reserve(struct rchan_buf *buf, |
279 | size_t length) |
280 | { |
281 | BUG_ON(length >= buf->chan->subbuf_size - 1); |
282 | buf->offset = length; |
283 | } |
284 | |
285 | /* |
286 | * exported relay file operations, kernel/relay.c |
287 | */ |
288 | extern const struct file_operations relay_file_operations; |
289 | |
290 | #endif /* _LINUX_RELAY_H */ |
291 | |
292 |
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