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