summaryrefslogtreecommitdiff
path: root/include/linux/ring_buffer.h
blob: fa6ace66fea5e383bbcec98e064267667ad74b76 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_RING_BUFFER_H
#define _LINUX_RING_BUFFER_H

#include <linux/kmemcheck.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/poll.h>

struct ring_buffer;
struct ring_buffer_iter;

/*
 * Don't refer to this struct directly, use functions below.
 */
struct ring_buffer_event {
	kmemcheck_bitfield_begin(bitfield);
	u32		type_len:5, time_delta:27;
	kmemcheck_bitfield_end(bitfield);

	u32		array[];
};

/**
 * enum ring_buffer_type - internal ring buffer types
 *
 * @RINGBUF_TYPE_PADDING:	Left over page padding or discarded event
 *				 If time_delta is 0:
 *				  array is ignored
 *				  size is variable depending on how much
 *				  padding is needed
 *				 If time_delta is non zero:
 *				  array[0] holds the actual length
 *				  size = 4 + length (bytes)
 *
 * @RINGBUF_TYPE_TIME_EXTEND:	Extend the time delta
 *				 array[0] = time delta (28 .. 59)
 *				 size = 8 bytes
 *
 * @RINGBUF_TYPE_TIME_STAMP:	Sync time stamp with external clock
 *				 array[0]    = tv_nsec
 *				 array[1..2] = tv_sec
 *				 size = 16 bytes
 *
 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
 *				Data record
 *				 If type_len is zero:
 *				  array[0] holds the actual length
 *				  array[1..(length+3)/4] holds data
 *				  size = 4 + length (bytes)
 *				 else
 *				  length = type_len << 2
 *				  array[0..(length+3)/4-1] holds data
 *				  size = 4 + length (bytes)
 */
enum ring_buffer_type {
	RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
	RINGBUF_TYPE_PADDING,
	RINGBUF_TYPE_TIME_EXTEND,
	/* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
	RINGBUF_TYPE_TIME_STAMP,
};

unsigned ring_buffer_event_length(struct ring_buffer_event *event);
void *ring_buffer_event_data(struct ring_buffer_event *event);

/*
 * ring_buffer_discard_commit will remove an event that has not
 *   ben committed yet. If this is used, then ring_buffer_unlock_commit
 *   must not be called on the discarded event. This function
 *   will try to remove the event from the ring buffer completely
 *   if another event has not been written after it.
 *
 * Example use:
 *
 *  if (some_condition)
 *    ring_buffer_discard_commit(buffer, event);
 *  else
 *    ring_buffer_unlock_commit(buffer, event);
 */
void ring_buffer_discard_commit(struct ring_buffer *buffer,
				struct ring_buffer_event *event);

/*
 * size is in bytes for each per CPU buffer.
 */
struct ring_buffer *
__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);

/*
 * Because the ring buffer is generic, if other users of the ring buffer get
 * traced by ftrace, it can produce lockdep warnings. We need to keep each
 * ring buffer's lock class separate.
 */
#define ring_buffer_alloc(size, flags)			\
({							\
	static struct lock_class_key __key;		\
	__ring_buffer_alloc((size), (flags), &__key);	\
})

int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full);
int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
			  struct file *filp, poll_table *poll_table);


#define RING_BUFFER_ALL_CPUS -1

void ring_buffer_free(struct ring_buffer *buffer);

int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);

void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);

struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
						   unsigned long length);
int ring_buffer_unlock_commit(struct ring_buffer *buffer,
			      struct ring_buffer_event *event);
int ring_buffer_write(struct ring_buffer *buffer,
		      unsigned long length, void *data);

struct ring_buffer_event *
ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
		 unsigned long *lost_events);
struct ring_buffer_event *
ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
		    unsigned long *lost_events);

struct ring_buffer_iter *
ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
void ring_buffer_read_prepare_sync(void);
void ring_buffer_read_start(struct ring_buffer_iter *iter);
void ring_buffer_read_finish(struct ring_buffer_iter *iter);

struct ring_buffer_event *
ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
struct ring_buffer_event *
ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
int ring_buffer_iter_empty(struct ring_buffer_iter *iter);

unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);

void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
void ring_buffer_reset(struct ring_buffer *buffer);

#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
			 struct ring_buffer *buffer_b, int cpu);
#else
static inline int
ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
		     struct ring_buffer *buffer_b, int cpu)
{
	return -ENODEV;
}
#endif

bool ring_buffer_empty(struct ring_buffer *buffer);
bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);

void ring_buffer_record_disable(struct ring_buffer *buffer);
void ring_buffer_record_enable(struct ring_buffer *buffer);
void ring_buffer_record_off(struct ring_buffer *buffer);
void ring_buffer_record_on(struct ring_buffer *buffer);
int ring_buffer_record_is_on(struct ring_buffer *buffer);
void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);

u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_entries(struct ring_buffer *buffer);
unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);

u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
				      int cpu, u64 *ts);
void ring_buffer_set_clock(struct ring_buffer *buffer,
			   u64 (*clock)(void));

size_t ring_buffer_page_len(void *page);


void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
			  size_t len, int cpu, int full);

struct trace_seq;

int ring_buffer_print_entry_header(struct trace_seq *s);
int ring_buffer_print_page_header(struct trace_seq *s);

enum ring_buffer_flags {
	RB_FL_OVERWRITE		= 1 << 0,
};

#ifdef CONFIG_RING_BUFFER
int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
#else
#define trace_rb_cpu_prepare	NULL
#endif

#endif /* _LINUX_RING_BUFFER_H */