include/linux/ring_buffer.h

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