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 refer to 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..2] = 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] holds data
  39  *                                size = 4 + 4 + length (bytes)
  40  *                               else
  41  *                                length = len << 2
  42  *                                array[0..(length+3)/4-1] holds data
  43  *                                size = 4 + length (bytes)
  44  */
  45 enum ring_buffer_type {
  46         RINGBUF_TYPE_PADDING,
  47         RINGBUF_TYPE_TIME_EXTEND,
  48         /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
  49         RINGBUF_TYPE_TIME_STAMP,
  50         RINGBUF_TYPE_DATA,
  51 };
  52
  53 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
  54 void *ring_buffer_event_data(struct ring_buffer_event *event);
  55
  56 /**
  57  * ring_buffer_event_time_delta - return the delta timestamp of the event
  58  * @event: the event to get the delta timestamp of
  59  *
  60  * The delta timestamp is the 27 bit timestamp since the last event.
  61  */
  62 static inline unsigned
  63 ring_buffer_event_time_delta(struct ring_buffer_event *event)
  64 {
  65         return event->time_delta;
  66 }
  67
  68 /*
  69  * size is in bytes for each per CPU buffer.
  70  */
  71 struct ring_buffer *
  72 ring_buffer_alloc(unsigned long size, unsigned flags);
  73 void ring_buffer_free(struct ring_buffer *buffer);
  74
  75 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
  76
  77 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
  78                                                    unsigned long length);
  79 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
  80                               struct ring_buffer_event *event);
  81 int ring_buffer_write(struct ring_buffer *buffer,
  82                       unsigned long length, void *data);
  83
  84 struct ring_buffer_event *
  85 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts);
  86 struct ring_buffer_event *
  87 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts);
  88
  89 struct ring_buffer_iter *
  90 ring_buffer_read_start(struct ring_buffer *buffer, int cpu);
  91 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
  92
  93 struct ring_buffer_event *
  94 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
  95 struct ring_buffer_event *
  96 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
  97 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
  98 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
  99
 100 unsigned long ring_buffer_size(struct ring_buffer *buffer);
 101
 102 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 103 void ring_buffer_reset(struct ring_buffer *buffer);
 104
 105 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 106                          struct ring_buffer *buffer_b, int cpu);
 107
 108 int ring_buffer_empty(struct ring_buffer *buffer);
 109 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 110
 111 void ring_buffer_record_disable(struct ring_buffer *buffer);
 112 void ring_buffer_record_enable(struct ring_buffer *buffer);
 113 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 114 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 115
 116 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 117 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 118 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 119 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 120
 121 u64 ring_buffer_time_stamp(int cpu);
 122 void ring_buffer_normalize_time_stamp(int cpu, u64 *ts);
 123
 124 size_t ring_buffer_page_len(void *page);
 125
 126
 127 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
 128 void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 129 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 130                           size_t len, int cpu, int full);
 131
 132 enum ring_buffer_flags {
 133         RB_FL_OVERWRITE         = 1 << 0,
 134 };
 135
 136 #endif /* _LINUX_RING_BUFFER_H */