1 #ifndef _LIB_RING_BUFFER_FRONTEND_H
2 #define _LIB_RING_BUFFER_FRONTEND_H
5 * lib/ringbuffer/frontend.h
7 * Ring Buffer Library Synchronization Header (API).
9 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
26 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
28 * See ring_buffer_frontend.c for more information on wait-free algorithms.
31 #include <linux/pipe_fs_i.h>
32 #include <linux/rcupdate.h>
33 #include <linux/cpumask.h>
34 #include <linux/module.h>
35 #include <linux/bitops.h>
36 #include <linux/splice.h>
37 #include <linux/string.h>
38 #include <linux/timer.h>
39 #include <linux/sched.h>
40 #include <linux/cache.h>
41 #include <linux/time.h>
42 #include <linux/slab.h>
43 #include <linux/init.h>
44 #include <linux/stat.h>
45 #include <linux/cpu.h>
48 #include <asm/atomic.h>
49 #include <asm/local.h>
51 /* Internal helpers */
52 #include "../../wrapper/ringbuffer/frontend_internal.h"
54 /* Buffer creation/removal and setup operations */
57 * switch_timer_interval is the time interval (in us) to fill sub-buffers with
58 * padding to let readers get those sub-buffers. Used for live streaming.
60 * read_timer_interval is the time interval (in us) to wake up pending readers.
62 * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
63 * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
64 * be set to NULL for other backends.
68 struct channel *channel_create(const struct lib_ring_buffer_config *config,
69 const char *name, void *priv,
71 size_t subbuf_size, size_t num_subbuf,
72 unsigned int switch_timer_interval,
73 unsigned int read_timer_interval);
76 * channel_destroy returns the private data pointer. It finalizes all channel's
77 * buffers, waits for readers to release all references, and destroys the
81 void *channel_destroy(struct channel *chan);
84 /* Buffer read operations */
87 * Iteration on channel cpumask needs to issue a read barrier to match the write
88 * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
89 * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
90 * only performed at channel destruction.
92 #define for_each_channel_cpu(cpu, chan) \
94 ({ (cpu) = cpumask_next(cpu, (chan)->backend.cpumask); \
95 smp_read_barrier_depends(); (cpu) < nr_cpu_ids; });)
97 extern struct lib_ring_buffer *channel_get_ring_buffer(
98 const struct lib_ring_buffer_config *config,
99 struct channel *chan, int cpu);
100 extern int lib_ring_buffer_open_read(struct lib_ring_buffer *buf);
101 extern void lib_ring_buffer_release_read(struct lib_ring_buffer *buf);
104 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
106 extern int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf,
107 unsigned long *consumed,
108 unsigned long *produced);
109 extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
110 unsigned long consumed_new);
112 extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf,
113 unsigned long consumed);
114 extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf);
117 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
118 * to read sub-buffers sequentially.
120 static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer *buf)
124 ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
125 &buf->prod_snapshot);
128 ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot);
132 static inline void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer *buf)
134 lib_ring_buffer_put_subbuf(buf);
135 lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
139 extern void channel_reset(struct channel *chan);
140 extern void lib_ring_buffer_reset(struct lib_ring_buffer *buf);
143 unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config *config,
144 struct lib_ring_buffer *buf)
146 return v_read(config, &buf->offset);
150 unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config *config,
151 struct lib_ring_buffer *buf)
153 return atomic_long_read(&buf->consumed);
157 * Must call lib_ring_buffer_is_finalized before reading counters (memory
158 * ordering enforced with respect to trace teardown).
161 int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config *config,
162 struct lib_ring_buffer *buf)
164 int finalized = ACCESS_ONCE(buf->finalized);
166 * Read finalized before counters.
173 int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
175 return chan->finalized;
179 int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
181 return atomic_read(&chan->record_disabled);
185 unsigned long lib_ring_buffer_get_read_data_size(
186 const struct lib_ring_buffer_config *config,
187 struct lib_ring_buffer *buf)
189 return subbuffer_get_read_data_size(config, &buf->backend);
193 unsigned long lib_ring_buffer_get_records_count(
194 const struct lib_ring_buffer_config *config,
195 struct lib_ring_buffer *buf)
197 return v_read(config, &buf->records_count);
201 unsigned long lib_ring_buffer_get_records_overrun(
202 const struct lib_ring_buffer_config *config,
203 struct lib_ring_buffer *buf)
205 return v_read(config, &buf->records_overrun);
209 unsigned long lib_ring_buffer_get_records_lost_full(
210 const struct lib_ring_buffer_config *config,
211 struct lib_ring_buffer *buf)
213 return v_read(config, &buf->records_lost_full);
217 unsigned long lib_ring_buffer_get_records_lost_wrap(
218 const struct lib_ring_buffer_config *config,
219 struct lib_ring_buffer *buf)
221 return v_read(config, &buf->records_lost_wrap);
225 unsigned long lib_ring_buffer_get_records_lost_big(
226 const struct lib_ring_buffer_config *config,
227 struct lib_ring_buffer *buf)
229 return v_read(config, &buf->records_lost_big);
233 unsigned long lib_ring_buffer_get_records_read(
234 const struct lib_ring_buffer_config *config,
235 struct lib_ring_buffer *buf)
237 return v_read(config, &buf->backend.records_read);
240 #endif /* _LIB_RING_BUFFER_FRONTEND_H */