include/linux/ring_buffer.h

   1 #ifndef _LINUX_RING_BUFFER_H
   2 #define _LINUX_RING_BUFFER_H
   3
   4 #include <linux/mm.h>
   5 #include <linux/seq_file.h>
   6
   7 struct ring_buffer;
   8 struct ring_buffer_iter;
   9
  10 /*
  11  * Don't reference this struct directly, use functions below.
  12  */
  13 struct ring_buffer_event {
  14         u32             type:2, len:3, time_delta:27;
  15         u32             array[];
  16 };
  17
  18 /**
  19  * enum ring_buffer_type - internal ring buffer types
  20  *
  21  * @RINGBUF_TYPE_PADDING:       Left over page padding
  22  *                               array is ignored
  23  *                               size is variable depending on how much
  24  *                                padding is needed
  25  *
  26  * @RINGBUF_TYPE_TIME_EXTEND:   Extend the time delta
  27  *                               array[0] = time delta (28 .. 59)
  28  *                               size = 8 bytes
  29  *
  30  * @RINGBUF_TYPE_TIME_STAMP:    Sync time stamp with external clock
  31  *                               array[0] = tv_nsec
  32  *                               array[1] = tv_sec
  33  *                               size = 16 bytes
  34  *
  35  * @RINGBUF_TYPE_DATA:          Data record
  36  *                               If len is zero:
  37  *                                array[0] holds the actual length
  38  *                                array[1..(length+3)/4-1] holds data
  39  *                               else
  40  *                                length = len << 2
  41  *                                array[0..(length+3)/4] holds data
  42  */
  43 enum ring_buffer_type {
  44         RINGBUF_TYPE_PADDING,
  45         RINGBUF_TYPE_TIME_EXTEND,
  46         /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
  47         RINGBUF_TYPE_TIME_STAMP,
  48         RINGBUF_TYPE_DATA,
  49 };
  50
  51 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
  52 void *ring_buffer_event_data(struct ring_buffer_event *event);
  53
  54 /**
  55  * ring_buffer_event_time_delta - return the delta timestamp of the event
  56  * @event: the event to get the delta timestamp of
  57  *
  58  * The delta timestamp is the 27 bit timestamp since the last event.
  59  */
  60 static inline unsigned
  61 ring_buffer_event_time_delta(struct ring_buffer_event *event)
  62 {
  63         return event->time_delta;
  64 }
  65
  66 /*
  67  * size is in bytes for each per CPU buffer.
  68  */
  69 struct ring_buffer *
  70 ring_buffer_alloc(unsigned long size, unsigned flags);
  71 void ring_buffer_free(struct ring_buffer *buffer);
  72
  73 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
  74
  75 struct ring_buffer_event *
  76 ring_buffer_lock_reserve(struct ring_buffer *buffer,
  77                          unsigned long length,
  78                          unsigned long *flags);
  79 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
  80                               struct ring_buffer_event *event,
  81                               unsigned long flags);
  82 int ring_buffer_write(struct ring_buffer *buffer,
  83                       unsigned long length, void *data);
  84
  85 struct ring_buffer_event *
  86 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts);
  87 struct ring_buffer_event *
  88 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts);
  89
  90 struct ring_buffer_iter *
  91 ring_buffer_read_start(struct ring_buffer *buffer, int cpu);
  92 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
  93
  94 struct ring_buffer_event *
  95 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
  96 struct ring_buffer_event *
  97 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
  98 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
  99 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 100
 101 unsigned long ring_buffer_size(struct ring_buffer *buffer);
 102
 103 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 104 void ring_buffer_reset(struct ring_buffer *buffer);
 105
 106 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 107                          struct ring_buffer *buffer_b, int cpu);
 108
 109 int ring_buffer_empty(struct ring_buffer *buffer);
 110 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 111
 112 void ring_buffer_record_disable(struct ring_buffer *buffer);
 113 void ring_buffer_record_enable(struct ring_buffer *buffer);
 114 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 115 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 116
 117 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 118 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 119
 120 u64 ring_buffer_time_stamp(int cpu);
 121 void ring_buffer_normalize_time_stamp(int cpu, u64 *ts);
 122
 123 enum ring_buffer_flags {
 124         RB_FL_OVERWRITE         = 1 << 0,
 125 };
 126
 127 #endif /* _LINUX_RING_BUFFER_H */