include/linux/ring_buffer.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_RING_BUFFER_H
   3 #define _LINUX_RING_BUFFER_H
   4
   5 #include <linux/mm.h>
   6 #include <linux/seq_file.h>
   7 #include <linux/poll.h>
   8
   9 struct ring_buffer;
  10 struct ring_buffer_iter;
  11
  12 /*
  13  * Don't refer to this struct directly, use functions below.
  14  */
  15 struct ring_buffer_event {
  16         u32             type_len:5, time_delta:27;
  17
  18         u32             array[];
  19 };
  20
  21 /**
  22  * enum ring_buffer_type - internal ring buffer types
  23  *
  24  * @RINGBUF_TYPE_PADDING:       Left over page padding or discarded event
  25  *                               If time_delta is 0:
  26  *                                array is ignored
  27  *                                size is variable depending on how much
  28  *                                padding is needed
  29  *                               If time_delta is non zero:
  30  *                                array[0] holds the actual length
  31  *                                size = 4 + length (bytes)
  32  *
  33  * @RINGBUF_TYPE_TIME_EXTEND:   Extend the time delta
  34  *                               array[0] = time delta (28 .. 59)
  35  *                               size = 8 bytes
  36  *
  37  * @RINGBUF_TYPE_TIME_STAMP:    Sync time stamp with external clock
  38  *                               array[0]    = tv_nsec
  39  *                               array[1..2] = tv_sec
  40  *                               size = 16 bytes
  41  *
  42  * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
  43  *                              Data record
  44  *                               If type_len is zero:
  45  *                                array[0] holds the actual length
  46  *                                array[1..(length+3)/4] holds data
  47  *                                size = 4 + length (bytes)
  48  *                               else
  49  *                                length = type_len << 2
  50  *                                array[0..(length+3)/4-1] holds data
  51  *                                size = 4 + length (bytes)
  52  */
  53 enum ring_buffer_type {
  54         RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
  55         RINGBUF_TYPE_PADDING,
  56         RINGBUF_TYPE_TIME_EXTEND,
  57         /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
  58         RINGBUF_TYPE_TIME_STAMP,
  59 };
  60
  61 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
  62 void *ring_buffer_event_data(struct ring_buffer_event *event);
  63
  64 /*
  65  * ring_buffer_discard_commit will remove an event that has not
  66  *   ben committed yet. If this is used, then ring_buffer_unlock_commit
  67  *   must not be called on the discarded event. This function
  68  *   will try to remove the event from the ring buffer completely
  69  *   if another event has not been written after it.
  70  *
  71  * Example use:
  72  *
  73  *  if (some_condition)
  74  *    ring_buffer_discard_commit(buffer, event);
  75  *  else
  76  *    ring_buffer_unlock_commit(buffer, event);
  77  */
  78 void ring_buffer_discard_commit(struct ring_buffer *buffer,
  79                                 struct ring_buffer_event *event);
  80
  81 /*
  82  * size is in bytes for each per CPU buffer.
  83  */
  84 struct ring_buffer *
  85 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
  86
  87 /*
  88  * Because the ring buffer is generic, if other users of the ring buffer get
  89  * traced by ftrace, it can produce lockdep warnings. We need to keep each
  90  * ring buffer's lock class separate.
  91  */
  92 #define ring_buffer_alloc(size, flags)                  \
  93 ({                                                      \
  94         static struct lock_class_key __key;             \
  95         __ring_buffer_alloc((size), (flags), &__key);   \
  96 })
  97
  98 int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full);
  99 __poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
 100                           struct file *filp, poll_table *poll_table);
 101
 102
 103 #define RING_BUFFER_ALL_CPUS -1
 104
 105 void ring_buffer_free(struct ring_buffer *buffer);
 106
 107 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
 108
 109 void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
 110
 111 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 112                                                    unsigned long length);
 113 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 114                               struct ring_buffer_event *event);
 115 int ring_buffer_write(struct ring_buffer *buffer,
 116                       unsigned long length, void *data);
 117
 118 struct ring_buffer_event *
 119 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
 120                  unsigned long *lost_events);
 121 struct ring_buffer_event *
 122 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
 123                     unsigned long *lost_events);
 124
 125 struct ring_buffer_iter *
 126 ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
 127 void ring_buffer_read_prepare_sync(void);
 128 void ring_buffer_read_start(struct ring_buffer_iter *iter);
 129 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 130
 131 struct ring_buffer_event *
 132 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 133 struct ring_buffer_event *
 134 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 135 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 136 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 137
 138 unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
 139
 140 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 141 void ring_buffer_reset(struct ring_buffer *buffer);
 142
 143 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 144 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 145                          struct ring_buffer *buffer_b, int cpu);
 146 #else
 147 static inline int
 148 ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 149                      struct ring_buffer *buffer_b, int cpu)
 150 {
 151         return -ENODEV;
 152 }
 153 #endif
 154
 155 bool ring_buffer_empty(struct ring_buffer *buffer);
 156 bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 157
 158 void ring_buffer_record_disable(struct ring_buffer *buffer);
 159 void ring_buffer_record_enable(struct ring_buffer *buffer);
 160 void ring_buffer_record_off(struct ring_buffer *buffer);
 161 void ring_buffer_record_on(struct ring_buffer *buffer);
 162 int ring_buffer_record_is_on(struct ring_buffer *buffer);
 163 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 164 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 165
 166 u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
 167 unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
 168 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 169 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 170 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 171 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 172 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 173 unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
 174 unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
 175
 176 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 177 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 178                                       int cpu, u64 *ts);
 179 void ring_buffer_set_clock(struct ring_buffer *buffer,
 180                            u64 (*clock)(void));
 181
 182 size_t ring_buffer_page_len(void *page);
 183
 184
 185 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
 186 void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
 187 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 188                           size_t len, int cpu, int full);
 189
 190 struct trace_seq;
 191
 192 int ring_buffer_print_entry_header(struct trace_seq *s);
 193 int ring_buffer_print_page_header(struct trace_seq *s);
 194
 195 enum ring_buffer_flags {
 196         RB_FL_OVERWRITE         = 1 << 0,
 197 };
 198
 199 #ifdef CONFIG_RING_BUFFER
 200 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
 201 #else
 202 #define trace_rb_cpu_prepare    NULL
 203 #endif
 204
 205 #endif /* _LINUX_RING_BUFFER_H */