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1 | #ifndef _LINUX_RING_BUFFER_FRONTEND_H |
2 | #define _LINUX_RING_BUFFER_FRONTEND_H | |
3 | ||
4 | /* | |
5 | * linux/ringbuffer/frontend.h | |
6 | * | |
7 | * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
8 | * | |
9 | * Ring Buffer Library Synchronization Header (API). | |
10 | * | |
11 | * Author: | |
12 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
13 | * | |
14 | * See ring_buffer_frontend.c for more information on wait-free algorithms. | |
15 | * | |
16 | * Dual LGPL v2.1/GPL v2 license. | |
17 | */ | |
18 | ||
19 | #include <linux/pipe_fs_i.h> | |
20 | #include <linux/rcupdate.h> | |
21 | #include <linux/cpumask.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/bitops.h> | |
24 | #include <linux/splice.h> | |
25 | #include <linux/string.h> | |
26 | #include <linux/timer.h> | |
27 | #include <linux/sched.h> | |
28 | #include <linux/cache.h> | |
29 | #include <linux/time.h> | |
30 | #include <linux/slab.h> | |
31 | #include <linux/init.h> | |
32 | #include <linux/stat.h> | |
33 | #include <linux/cpu.h> | |
34 | #include <linux/fs.h> | |
35 | ||
36 | #include <asm/atomic.h> | |
37 | #include <asm/local.h> | |
38 | ||
39 | /* Internal helpers */ | |
40 | #include "../../wrapper/ringbuffer/frontend_internal.h" | |
41 | ||
42 | /* Buffer creation/removal and setup operations */ | |
43 | ||
44 | /* | |
45 | * switch_timer_interval is the time interval (in us) to fill sub-buffers with | |
46 | * padding to let readers get those sub-buffers. Used for live streaming. | |
47 | * | |
48 | * read_timer_interval is the time interval (in us) to wake up pending readers. | |
49 | * | |
50 | * buf_addr is a pointer the the beginning of the preallocated buffer contiguous | |
51 | * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can | |
52 | * be set to NULL for other backends. | |
53 | */ | |
54 | ||
55 | extern | |
56 | struct channel *channel_create(const struct lib_ring_buffer_config *config, | |
57 | const char *name, void *priv, | |
58 | void *buf_addr, | |
59 | size_t subbuf_size, size_t num_subbuf, | |
60 | unsigned int switch_timer_interval, | |
61 | unsigned int read_timer_interval); | |
62 | ||
63 | /* | |
64 | * channel_destroy returns the private data pointer. It finalizes all channel's | |
65 | * buffers, waits for readers to release all references, and destroys the | |
66 | * channel. | |
67 | */ | |
68 | extern | |
69 | void *channel_destroy(struct channel *chan); | |
70 | ||
71 | ||
72 | /* Buffer read operations */ | |
73 | ||
74 | /* | |
75 | * Iteration on channel cpumask needs to issue a read barrier to match the write | |
76 | * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu | |
77 | * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is | |
78 | * only performed at channel destruction. | |
79 | */ | |
80 | #define for_each_channel_cpu(cpu, chan) \ | |
81 | for ((cpu) = -1; \ | |
82 | ({ (cpu) = cpumask_next(cpu, (chan)->backend.cpumask); \ | |
83 | smp_read_barrier_depends(); (cpu) < nr_cpu_ids; });) | |
84 | ||
85 | extern struct lib_ring_buffer *channel_get_ring_buffer( | |
86 | const struct lib_ring_buffer_config *config, | |
87 | struct channel *chan, int cpu); | |
88 | extern int lib_ring_buffer_open_read(struct lib_ring_buffer *buf); | |
89 | extern void lib_ring_buffer_release_read(struct lib_ring_buffer *buf); | |
90 | ||
91 | /* | |
92 | * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer. | |
93 | */ | |
94 | extern int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf, | |
95 | unsigned long *consumed, | |
96 | unsigned long *produced); | |
97 | extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf, | |
98 | unsigned long consumed_new); | |
99 | ||
100 | extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf, | |
101 | unsigned long consumed); | |
102 | extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf); | |
103 | ||
104 | /* | |
105 | * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers | |
106 | * to read sub-buffers sequentially. | |
107 | */ | |
108 | static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer *buf) | |
109 | { | |
110 | int ret; | |
111 | ||
112 | ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot, | |
113 | &buf->prod_snapshot); | |
114 | if (ret) | |
115 | return ret; | |
116 | ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot); | |
117 | return ret; | |
118 | } | |
119 | ||
120 | static inline void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer *buf) | |
121 | { | |
122 | lib_ring_buffer_put_subbuf(buf); | |
123 | lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot, | |
124 | buf->backend.chan)); | |
125 | } | |
126 | ||
127 | extern void channel_reset(struct channel *chan); | |
128 | extern void lib_ring_buffer_reset(struct lib_ring_buffer *buf); | |
129 | ||
130 | static inline | |
131 | unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config *config, | |
132 | struct lib_ring_buffer *buf) | |
133 | { | |
134 | return v_read(config, &buf->offset); | |
135 | } | |
136 | ||
137 | static inline | |
138 | unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config *config, | |
139 | struct lib_ring_buffer *buf) | |
140 | { | |
141 | return atomic_long_read(&buf->consumed); | |
142 | } | |
143 | ||
144 | /* | |
145 | * Must call lib_ring_buffer_is_finalized before reading counters (memory | |
146 | * ordering enforced with respect to trace teardown). | |
147 | */ | |
148 | static inline | |
149 | int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config *config, | |
150 | struct lib_ring_buffer *buf) | |
151 | { | |
152 | int finalized = ACCESS_ONCE(buf->finalized); | |
153 | /* | |
154 | * Read finalized before counters. | |
155 | */ | |
156 | smp_rmb(); | |
157 | return finalized; | |
158 | } | |
159 | ||
160 | static inline | |
161 | unsigned long lib_ring_buffer_get_read_data_size( | |
162 | const struct lib_ring_buffer_config *config, | |
163 | struct lib_ring_buffer *buf) | |
164 | { | |
165 | return subbuffer_get_read_data_size(config, &buf->backend); | |
166 | } | |
167 | ||
168 | static inline | |
169 | unsigned long lib_ring_buffer_get_records_count( | |
170 | const struct lib_ring_buffer_config *config, | |
171 | struct lib_ring_buffer *buf) | |
172 | { | |
173 | return v_read(config, &buf->records_count); | |
174 | } | |
175 | ||
176 | static inline | |
177 | unsigned long lib_ring_buffer_get_records_overrun( | |
178 | const struct lib_ring_buffer_config *config, | |
179 | struct lib_ring_buffer *buf) | |
180 | { | |
181 | return v_read(config, &buf->records_overrun); | |
182 | } | |
183 | ||
184 | static inline | |
185 | unsigned long lib_ring_buffer_get_records_lost_full( | |
186 | const struct lib_ring_buffer_config *config, | |
187 | struct lib_ring_buffer *buf) | |
188 | { | |
189 | return v_read(config, &buf->records_lost_full); | |
190 | } | |
191 | ||
192 | static inline | |
193 | unsigned long lib_ring_buffer_get_records_lost_wrap( | |
194 | const struct lib_ring_buffer_config *config, | |
195 | struct lib_ring_buffer *buf) | |
196 | { | |
197 | return v_read(config, &buf->records_lost_wrap); | |
198 | } | |
199 | ||
200 | static inline | |
201 | unsigned long lib_ring_buffer_get_records_lost_big( | |
202 | const struct lib_ring_buffer_config *config, | |
203 | struct lib_ring_buffer *buf) | |
204 | { | |
205 | return v_read(config, &buf->records_lost_big); | |
206 | } | |
207 | ||
208 | static inline | |
209 | unsigned long lib_ring_buffer_get_records_read( | |
210 | const struct lib_ring_buffer_config *config, | |
211 | struct lib_ring_buffer *buf) | |
212 | { | |
213 | return v_read(config, &buf->backend.records_read); | |
214 | } | |
215 | ||
f3bc08c5 | 216 | #endif /* _LINUX_RING_BUFFER_FRONTEND_H */ |