include/linux/ring_buffer.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _LINUX_RING_BUFFER_H
0003 #define _LINUX_RING_BUFFER_H
0004
0005 #include <linux/mm.h>
0006 #include <linux/seq_file.h>
0007 #include <linux/poll.h>
0008
0009 struct trace_buffer;
0010 struct ring_buffer_iter;
0011
0012 /*
0013  * Don't refer to this struct directly, use functions below.
0014  */
0015 struct ring_buffer_event {
0016     u32     type_len:5, time_delta:27;
0017
0018     u32     array[];
0019 };
0020
0021 /**
0022  * enum ring_buffer_type - internal ring buffer types
0023  *
0024  * @RINGBUF_TYPE_PADDING:   Left over page padding or discarded event
0025  *               If time_delta is 0:
0026  *                array is ignored
0027  *                size is variable depending on how much
0028  *                padding is needed
0029  *               If time_delta is non zero:
0030  *                array[0] holds the actual length
0031  *                size = 4 + length (bytes)
0032  *
0033  * @RINGBUF_TYPE_TIME_EXTEND:   Extend the time delta
0034  *               array[0] = time delta (28 .. 59)
0035  *               size = 8 bytes
0036  *
0037  * @RINGBUF_TYPE_TIME_STAMP:    Absolute timestamp
0038  *               Same format as TIME_EXTEND except that the
0039  *               value is an absolute timestamp, not a delta
0040  *               event.time_delta contains bottom 27 bits
0041  *               array[0] = top (28 .. 59) bits
0042  *               size = 8 bytes
0043  *
0044  * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
0045  *              Data record
0046  *               If type_len is zero:
0047  *                array[0] holds the actual length
0048  *                array[1..(length+3)/4] holds data
0049  *                size = 4 + length (bytes)
0050  *               else
0051  *                length = type_len << 2
0052  *                array[0..(length+3)/4-1] holds data
0053  *                size = 4 + length (bytes)
0054  */
0055 enum ring_buffer_type {
0056     RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
0057     RINGBUF_TYPE_PADDING,
0058     RINGBUF_TYPE_TIME_EXTEND,
0059     RINGBUF_TYPE_TIME_STAMP,
0060 };
0061
0062 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
0063 void *ring_buffer_event_data(struct ring_buffer_event *event);
0064 u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer,
0065                  struct ring_buffer_event *event);
0066
0067 /*
0068  * ring_buffer_discard_commit will remove an event that has not
0069  *   been committed yet. If this is used, then ring_buffer_unlock_commit
0070  *   must not be called on the discarded event. This function
0071  *   will try to remove the event from the ring buffer completely
0072  *   if another event has not been written after it.
0073  *
0074  * Example use:
0075  *
0076  *  if (some_condition)
0077  *    ring_buffer_discard_commit(buffer, event);
0078  *  else
0079  *    ring_buffer_unlock_commit(buffer, event);
0080  */
0081 void ring_buffer_discard_commit(struct trace_buffer *buffer,
0082                 struct ring_buffer_event *event);
0083
0084 /*
0085  * size is in bytes for each per CPU buffer.
0086  */
0087 struct trace_buffer *
0088 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
0089
0090 /*
0091  * Because the ring buffer is generic, if other users of the ring buffer get
0092  * traced by ftrace, it can produce lockdep warnings. We need to keep each
0093  * ring buffer's lock class separate.
0094  */
0095 #define ring_buffer_alloc(size, flags)          \
0096 ({                          \
0097     static struct lock_class_key __key;     \
0098     __ring_buffer_alloc((size), (flags), &__key);   \
0099 })
0100
0101 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full);
0102 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
0103               struct file *filp, poll_table *poll_table);
0104
0105
0106 #define RING_BUFFER_ALL_CPUS -1
0107
0108 void ring_buffer_free(struct trace_buffer *buffer);
0109
0110 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
0111
0112 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
0113
0114 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
0115                            unsigned long length);
0116 int ring_buffer_unlock_commit(struct trace_buffer *buffer,
0117                   struct ring_buffer_event *event);
0118 int ring_buffer_write(struct trace_buffer *buffer,
0119               unsigned long length, void *data);
0120
0121 void ring_buffer_nest_start(struct trace_buffer *buffer);
0122 void ring_buffer_nest_end(struct trace_buffer *buffer);
0123
0124 struct ring_buffer_event *
0125 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
0126          unsigned long *lost_events);
0127 struct ring_buffer_event *
0128 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
0129             unsigned long *lost_events);
0130
0131 struct ring_buffer_iter *
0132 ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
0133 void ring_buffer_read_prepare_sync(void);
0134 void ring_buffer_read_start(struct ring_buffer_iter *iter);
0135 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
0136
0137 struct ring_buffer_event *
0138 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
0139 void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
0140 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
0141 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
0142 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
0143
0144 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
0145
0146 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
0147 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
0148 void ring_buffer_reset(struct trace_buffer *buffer);
0149
0150 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
0151 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
0152              struct trace_buffer *buffer_b, int cpu);
0153 #else
0154 static inline int
0155 ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
0156              struct trace_buffer *buffer_b, int cpu)
0157 {
0158     return -ENODEV;
0159 }
0160 #endif
0161
0162 bool ring_buffer_empty(struct trace_buffer *buffer);
0163 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
0164
0165 void ring_buffer_record_disable(struct trace_buffer *buffer);
0166 void ring_buffer_record_enable(struct trace_buffer *buffer);
0167 void ring_buffer_record_off(struct trace_buffer *buffer);
0168 void ring_buffer_record_on(struct trace_buffer *buffer);
0169 bool ring_buffer_record_is_on(struct trace_buffer *buffer);
0170 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
0171 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
0172 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
0173
0174 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
0175 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
0176 unsigned long ring_buffer_entries(struct trace_buffer *buffer);
0177 unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
0178 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
0179 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
0180 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
0181 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
0182 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
0183
0184 u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
0185 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
0186                       int cpu, u64 *ts);
0187 void ring_buffer_set_clock(struct trace_buffer *buffer,
0188                u64 (*clock)(void));
0189 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
0190 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
0191
0192 size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu);
0193 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
0194
0195 void *ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
0196 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data);
0197 int ring_buffer_read_page(struct trace_buffer *buffer, void **data_page,
0198               size_t len, int cpu, int full);
0199
0200 struct trace_seq;
0201
0202 int ring_buffer_print_entry_header(struct trace_seq *s);
0203 int ring_buffer_print_page_header(struct trace_seq *s);
0204
0205 enum ring_buffer_flags {
0206     RB_FL_OVERWRITE     = 1 << 0,
0207 };
0208
0209 #ifdef CONFIG_RING_BUFFER
0210 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
0211 #else
0212 #define trace_rb_cpu_prepare    NULL
0213 #endif
0214
0215 #endif /* _LINUX_RING_BUFFER_H */