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1 | #ifndef _LIB_RING_BUFFER_BACKEND_H |
2 | #define _LIB_RING_BUFFER_BACKEND_H | |
f3bc08c5 MD |
3 | |
4 | /* | |
886d51a3 | 5 | * lib/ringbuffer/backend.h |
f3bc08c5 MD |
6 | * |
7 | * Ring buffer backend (API). | |
8 | * | |
886d51a3 MD |
9 | * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
10 | * | |
11 | * This library is free software; you can redistribute it and/or | |
12 | * modify it under the terms of the GNU Lesser General Public | |
13 | * License as published by the Free Software Foundation; only | |
14 | * version 2.1 of the License. | |
15 | * | |
16 | * This library is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
19 | * Lesser General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU Lesser General Public | |
22 | * License along with this library; if not, write to the Free Software | |
23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
f3bc08c5 MD |
24 | * |
25 | * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by | |
26 | * the reader in flight recorder mode. | |
27 | */ | |
28 | ||
29 | #include <linux/types.h> | |
30 | #include <linux/sched.h> | |
31 | #include <linux/timer.h> | |
32 | #include <linux/wait.h> | |
33 | #include <linux/poll.h> | |
34 | #include <linux/list.h> | |
35 | #include <linux/fs.h> | |
36 | #include <linux/mm.h> | |
37 | ||
38 | /* Internal helpers */ | |
39 | #include "../../wrapper/ringbuffer/backend_internal.h" | |
40 | #include "../../wrapper/ringbuffer/frontend_internal.h" | |
41 | ||
42 | /* Ring buffer backend API */ | |
43 | ||
44 | /* Ring buffer backend access (read/write) */ | |
45 | ||
46 | extern size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, | |
47 | size_t offset, void *dest, size_t len); | |
48 | ||
49 | extern int __lib_ring_buffer_copy_to_user(struct lib_ring_buffer_backend *bufb, | |
50 | size_t offset, void __user *dest, | |
51 | size_t len); | |
52 | ||
53 | extern int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, | |
54 | size_t offset, void *dest, size_t len); | |
55 | ||
56 | extern struct page ** | |
57 | lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb, size_t offset, | |
58 | void ***virt); | |
59 | ||
60 | /* | |
61 | * Return the address where a given offset is located. | |
62 | * Should be used to get the current subbuffer header pointer. Given we know | |
63 | * it's never on a page boundary, it's safe to write directly to this address, | |
64 | * as long as the write is never bigger than a page size. | |
65 | */ | |
66 | extern void * | |
67 | lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb, | |
68 | size_t offset); | |
69 | extern void * | |
70 | lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb, | |
71 | size_t offset); | |
72 | ||
73 | /** | |
74 | * lib_ring_buffer_write - write data to a buffer backend | |
75 | * @config : ring buffer instance configuration | |
76 | * @ctx: ring buffer context. (input arguments only) | |
77 | * @src : source pointer to copy from | |
78 | * @len : length of data to copy | |
79 | * | |
80 | * This function copies "len" bytes of data from a source pointer to a buffer | |
81 | * backend, at the current context offset. This is more or less a buffer | |
82 | * backend-specific memcpy() operation. Calls the slow path (_ring_buffer_write) | |
83 | * if copy is crossing a page boundary. | |
84 | */ | |
85 | static inline | |
86 | void lib_ring_buffer_write(const struct lib_ring_buffer_config *config, | |
87 | struct lib_ring_buffer_ctx *ctx, | |
88 | const void *src, size_t len) | |
89 | { | |
90 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
91 | struct channel_backend *chanb = &ctx->chan->backend; | |
92 | size_t sbidx, index; | |
93 | size_t offset = ctx->buf_offset; | |
94 | ssize_t pagecpy; | |
95 | struct lib_ring_buffer_backend_pages *rpages; | |
96 | unsigned long sb_bindex, id; | |
97 | ||
98 | offset &= chanb->buf_size - 1; | |
99 | sbidx = offset >> chanb->subbuf_size_order; | |
100 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
101 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
102 | id = bufb->buf_wsb[sbidx].id; | |
103 | sb_bindex = subbuffer_id_get_index(config, id); | |
104 | rpages = bufb->array[sb_bindex]; | |
105 | CHAN_WARN_ON(ctx->chan, | |
106 | config->mode == RING_BUFFER_OVERWRITE | |
107 | && subbuffer_id_is_noref(config, id)); | |
108 | if (likely(pagecpy == len)) | |
109 | lib_ring_buffer_do_copy(config, | |
110 | rpages->p[index].virt | |
111 | + (offset & ~PAGE_MASK), | |
112 | src, len); | |
113 | else | |
114 | _lib_ring_buffer_write(bufb, offset, src, len, 0); | |
115 | ctx->buf_offset += len; | |
116 | } | |
117 | ||
4ea00e4f JD |
118 | /** |
119 | * lib_ring_buffer_memset - write len bytes of c to a buffer backend | |
120 | * @config : ring buffer instance configuration | |
121 | * @bufb : ring buffer backend | |
122 | * @offset : offset within the buffer | |
123 | * @c : the byte to copy | |
124 | * @len : number of bytes to copy | |
125 | * | |
126 | * This function writes "len" bytes of "c" to a buffer backend, at a specific | |
127 | * offset. This is more or less a buffer backend-specific memset() operation. | |
128 | * Calls the slow path (_ring_buffer_memset) if write is crossing a page | |
129 | * boundary. | |
130 | */ | |
131 | static inline | |
132 | void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config, | |
133 | struct lib_ring_buffer_ctx *ctx, int c, size_t len) | |
134 | { | |
135 | ||
136 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
137 | struct channel_backend *chanb = &ctx->chan->backend; | |
138 | size_t sbidx, index; | |
139 | size_t offset = ctx->buf_offset; | |
140 | ssize_t pagecpy; | |
141 | struct lib_ring_buffer_backend_pages *rpages; | |
142 | unsigned long sb_bindex, id; | |
143 | ||
144 | offset &= chanb->buf_size - 1; | |
145 | sbidx = offset >> chanb->subbuf_size_order; | |
146 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
147 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
148 | id = bufb->buf_wsb[sbidx].id; | |
149 | sb_bindex = subbuffer_id_get_index(config, id); | |
150 | rpages = bufb->array[sb_bindex]; | |
151 | CHAN_WARN_ON(ctx->chan, | |
152 | config->mode == RING_BUFFER_OVERWRITE | |
153 | && subbuffer_id_is_noref(config, id)); | |
154 | if (likely(pagecpy == len)) | |
155 | lib_ring_buffer_do_memset(rpages->p[index].virt | |
156 | + (offset & ~PAGE_MASK), | |
157 | c, len); | |
158 | else | |
159 | _lib_ring_buffer_memset(bufb, offset, c, len, 0); | |
160 | ctx->buf_offset += len; | |
161 | } | |
162 | ||
163 | /** | |
164 | * lib_ring_buffer_copy_from_user - write userspace data to a buffer backend | |
165 | * @config : ring buffer instance configuration | |
166 | * @ctx: ring buffer context. (input arguments only) | |
167 | * @src : userspace source pointer to copy from | |
168 | * @len : length of data to copy | |
169 | * | |
170 | * This function copies "len" bytes of data from a userspace pointer to a | |
171 | * buffer backend, at the current context offset. This is more or less a buffer | |
172 | * backend-specific memcpy() operation. Calls the slow path | |
173 | * (_ring_buffer_write_from_user) if copy is crossing a page boundary. | |
174 | */ | |
175 | static inline | |
176 | void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config, | |
177 | struct lib_ring_buffer_ctx *ctx, | |
178 | const void __user *src, size_t len) | |
179 | { | |
180 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
181 | struct channel_backend *chanb = &ctx->chan->backend; | |
182 | size_t sbidx, index; | |
183 | size_t offset = ctx->buf_offset; | |
184 | ssize_t pagecpy; | |
185 | struct lib_ring_buffer_backend_pages *rpages; | |
186 | unsigned long sb_bindex, id; | |
187 | unsigned long ret; | |
188 | ||
189 | offset &= chanb->buf_size - 1; | |
190 | sbidx = offset >> chanb->subbuf_size_order; | |
191 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
192 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
193 | id = bufb->buf_wsb[sbidx].id; | |
194 | sb_bindex = subbuffer_id_get_index(config, id); | |
195 | rpages = bufb->array[sb_bindex]; | |
196 | CHAN_WARN_ON(ctx->chan, | |
197 | config->mode == RING_BUFFER_OVERWRITE | |
198 | && subbuffer_id_is_noref(config, id)); | |
199 | ||
200 | if (unlikely(!access_ok(VERIFY_READ, src, len))) | |
201 | goto fill_buffer; | |
202 | ||
203 | if (likely(pagecpy == len)) { | |
204 | ret = lib_ring_buffer_do_copy_from_user( | |
205 | rpages->p[index].virt + (offset & ~PAGE_MASK), | |
206 | src, len); | |
207 | if (unlikely(ret > 0)) { | |
208 | len -= (pagecpy - ret); | |
209 | offset += (pagecpy - ret); | |
210 | goto fill_buffer; | |
211 | } | |
212 | } else { | |
213 | _lib_ring_buffer_copy_from_user(bufb, offset, src, len, 0); | |
214 | } | |
215 | ctx->buf_offset += len; | |
216 | ||
217 | return; | |
218 | ||
219 | fill_buffer: | |
220 | /* | |
221 | * In the error path we call the slow path version to avoid | |
222 | * the pollution of static inline code. | |
223 | */ | |
224 | _lib_ring_buffer_memset(bufb, offset, 0, len, 0); | |
225 | } | |
226 | ||
f3bc08c5 MD |
227 | /* |
228 | * This accessor counts the number of unread records in a buffer. | |
229 | * It only provides a consistent value if no reads not writes are performed | |
230 | * concurrently. | |
231 | */ | |
232 | static inline | |
233 | unsigned long lib_ring_buffer_get_records_unread( | |
234 | const struct lib_ring_buffer_config *config, | |
235 | struct lib_ring_buffer *buf) | |
236 | { | |
237 | struct lib_ring_buffer_backend *bufb = &buf->backend; | |
238 | struct lib_ring_buffer_backend_pages *pages; | |
239 | unsigned long records_unread = 0, sb_bindex, id; | |
240 | unsigned int i; | |
241 | ||
242 | for (i = 0; i < bufb->chan->backend.num_subbuf; i++) { | |
243 | id = bufb->buf_wsb[i].id; | |
244 | sb_bindex = subbuffer_id_get_index(config, id); | |
245 | pages = bufb->array[sb_bindex]; | |
246 | records_unread += v_read(config, &pages->records_unread); | |
247 | } | |
248 | if (config->mode == RING_BUFFER_OVERWRITE) { | |
249 | id = bufb->buf_rsb.id; | |
250 | sb_bindex = subbuffer_id_get_index(config, id); | |
251 | pages = bufb->array[sb_bindex]; | |
252 | records_unread += v_read(config, &pages->records_unread); | |
253 | } | |
254 | return records_unread; | |
255 | } | |
256 | ||
257 | ssize_t lib_ring_buffer_file_splice_read(struct file *in, loff_t *ppos, | |
258 | struct pipe_inode_info *pipe, | |
259 | size_t len, unsigned int flags); | |
260 | loff_t lib_ring_buffer_no_llseek(struct file *file, loff_t offset, int origin); | |
261 | ||
886d51a3 | 262 | #endif /* _LIB_RING_BUFFER_BACKEND_H */ |