1 #ifndef _LINUX_RING_BUFFER_FRONTEND_H
2 #define _LINUX_RING_BUFFER_FRONTEND_H
5 * linux/ringbuffer/frontend.h
7 * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 * Ring Buffer Library Synchronization Header (API).
12 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
14 * See ring_buffer_frontend.c for more information on wait-free algorithms.
16 * Dual LGPL v2.1/GPL v2 license.
19 #include <urcu/compiler.h>
20 #include <urcu/uatomic.h>
22 /* Internal helpers */
23 #include "frontend_internal.h"
25 /* Buffer creation/removal and setup operations */
28 * switch_timer_interval is the time interval (in us) to fill sub-buffers with
29 * padding to let readers get those sub-buffers. Used for live streaming.
31 * read_timer_interval is the time interval (in us) to wake up pending readers.
33 * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
34 * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
35 * be set to NULL for other backends.
39 struct channel
*channel_create(const struct lib_ring_buffer_config
*config
,
40 const char *name
, void *priv
,
42 size_t subbuf_size
, size_t num_subbuf
,
43 unsigned int switch_timer_interval
,
44 unsigned int read_timer_interval
);
47 * channel_destroy returns the private data pointer. It finalizes all channel's
48 * buffers, waits for readers to release all references, and destroys the
52 void *channel_destroy(struct channel
*chan
);
55 /* Buffer read operations */
58 * Iteration on channel cpumask needs to issue a read barrier to match the write
59 * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
60 * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
61 * only performed at channel destruction.
63 #define for_each_channel_cpu(cpu, chan) \
65 ({ (cpu) = cpumask_next(cpu, (chan)->backend.cpumask); \
66 cmm_smp_read_barrier_depends(); (cpu) < nr_cpu_ids; });)
68 extern struct lib_ring_buffer
*channel_get_ring_buffer(
69 const struct lib_ring_buffer_config
*config
,
70 struct channel
*chan
, int cpu
);
71 extern int lib_ring_buffer_open_read(struct lib_ring_buffer
*buf
);
72 extern void lib_ring_buffer_release_read(struct lib_ring_buffer
*buf
);
75 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
77 extern int lib_ring_buffer_snapshot(struct lib_ring_buffer
*buf
,
78 unsigned long *consumed
,
79 unsigned long *produced
);
80 extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer
*buf
,
81 unsigned long consumed_new
);
83 extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer
*buf
,
84 unsigned long consumed
);
85 extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer
*buf
);
88 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
89 * to read sub-buffers sequentially.
91 static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer
*buf
)
95 ret
= lib_ring_buffer_snapshot(buf
, &buf
->cons_snapshot
,
99 ret
= lib_ring_buffer_get_subbuf(buf
, buf
->cons_snapshot
);
103 static inline void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer
*buf
)
105 lib_ring_buffer_put_subbuf(buf
);
106 lib_ring_buffer_move_consumer(buf
, subbuf_align(buf
->cons_snapshot
,
110 extern void channel_reset(struct channel
*chan
);
111 extern void lib_ring_buffer_reset(struct lib_ring_buffer
*buf
);
114 unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config
*config
,
115 struct lib_ring_buffer
*buf
)
117 return v_read(config
, &buf
->offset
);
121 unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config
*config
,
122 struct lib_ring_buffer
*buf
)
124 return uatomic_read(&buf
->consumed
);
128 * Must call lib_ring_buffer_is_finalized before reading counters (memory
129 * ordering enforced with respect to trace teardown).
132 int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config
*config
,
133 struct lib_ring_buffer
*buf
)
135 int finalized
= CMM_ACCESS_ONCE(buf
->finalized
);
137 * Read finalized before counters.
144 int lib_ring_buffer_channel_is_finalized(const struct channel
*chan
)
146 return chan
->finalized
;
150 int lib_ring_buffer_channel_is_disabled(const struct channel
*chan
)
152 return uatomic_read(&chan
->record_disabled
);
156 unsigned long lib_ring_buffer_get_read_data_size(
157 const struct lib_ring_buffer_config
*config
,
158 struct lib_ring_buffer
*buf
)
160 return subbuffer_get_read_data_size(config
, &buf
->backend
);
164 unsigned long lib_ring_buffer_get_records_count(
165 const struct lib_ring_buffer_config
*config
,
166 struct lib_ring_buffer
*buf
)
168 return v_read(config
, &buf
->records_count
);
172 unsigned long lib_ring_buffer_get_records_overrun(
173 const struct lib_ring_buffer_config
*config
,
174 struct lib_ring_buffer
*buf
)
176 return v_read(config
, &buf
->records_overrun
);
180 unsigned long lib_ring_buffer_get_records_lost_full(
181 const struct lib_ring_buffer_config
*config
,
182 struct lib_ring_buffer
*buf
)
184 return v_read(config
, &buf
->records_lost_full
);
188 unsigned long lib_ring_buffer_get_records_lost_wrap(
189 const struct lib_ring_buffer_config
*config
,
190 struct lib_ring_buffer
*buf
)
192 return v_read(config
, &buf
->records_lost_wrap
);
196 unsigned long lib_ring_buffer_get_records_lost_big(
197 const struct lib_ring_buffer_config
*config
,
198 struct lib_ring_buffer
*buf
)
200 return v_read(config
, &buf
->records_lost_big
);
204 unsigned long lib_ring_buffer_get_records_read(
205 const struct lib_ring_buffer_config
*config
,
206 struct lib_ring_buffer
*buf
)
208 return v_read(config
, &buf
->backend
.records_read
);
211 #endif /* _LINUX_RING_BUFFER_FRONTEND_H */
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