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 or discarded event
  22  *                               If time_delta is 0:
  23  *                                array is ignored
  24  *                                size is variable depending on how much
  25  *                                padding is needed
  26  *                               If time_delta is non zero:
  27  *                                everything else same as RINGBUF_TYPE_DATA
  28  *
  29  * @RINGBUF_TYPE_TIME_EXTEND:   Extend the time delta
  30  *                               array[0] = time delta (28 .. 59)
  31  *                               size = 8 bytes
  32  *
  33  * @RINGBUF_TYPE_TIME_STAMP:    Sync time stamp with external clock
  34  *                               array[0]    = tv_nsec
  35  *                               array[1..2] = tv_sec
  36  *                               size = 16 bytes
  37  *
  38  * @RINGBUF_TYPE_DATA:          Data record
  39  *                               If len is zero:
  40  *                                array[0] holds the actual length
  41  *                                array[1..(length+3)/4] holds data
  42  *                                size = 4 + 4 + length (bytes)
  43  *                               else
  44  *                                length = len << 2
  45  *                                array[0..(length+3)/4-1] holds data
  46  *                                size = 4 + length (bytes)
  47  */
  48 enum ring_buffer_type {
  49         RINGBUF_TYPE_PADDING,
  50         RINGBUF_TYPE_TIME_EXTEND,
  51         /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
  52         RINGBUF_TYPE_TIME_STAMP,
  53         RINGBUF_TYPE_DATA,
  54 };
  55
  56 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
  57 void *ring_buffer_event_data(struct ring_buffer_event *event);
  58
  59 /**
  60  * ring_buffer_event_time_delta - return the delta timestamp of the event
  61  * @event: the event to get the delta timestamp of
  62  *
  63  * The delta timestamp is the 27 bit timestamp since the last event.
  64  */
  65 static inline unsigned
  66 ring_buffer_event_time_delta(struct ring_buffer_event *event)
  67 {
  68         return event->time_delta;
  69 }
  70
  71 /*
  72  * ring_buffer_event_discard can discard any event in the ring buffer.
  73  *   it is up to the caller to protect against a reader from
  74  *   consuming it or a writer from wrapping and replacing it.
  75  *
  76  * No external protection is needed if this is called before
  77  * the event is commited. But in that case it would be better to
  78  * use ring_buffer_discard_commit.
  79  *
  80  * Note, if an event that has not been committed is discarded
  81  * with ring_buffer_event_discard, it must still be committed.
  82  */
  83 void ring_buffer_event_discard(struct ring_buffer_event *event);
  84
  85 /*
  86  * ring_buffer_discard_commit will remove an event that has not
  87  *   ben committed yet. If this is used, then ring_buffer_unlock_commit
  88  *   must not be called on the discarded event. This function
  89  *   will try to remove the event from the ring buffer completely
  90  *   if another event has not been written after it.
  91  *
  92  * Example use:
  93  *
  94  *  if (some_condition)
  95  *    ring_buffer_discard_commit(buffer, event);
  96  *  else
  97  *    ring_buffer_unlock_commit(buffer, event);
  98  */
  99 void ring_buffer_discard_commit(struct ring_buffer *buffer,
 100                                 struct ring_buffer_event *event);
 101
 102 /*
 103  * size is in bytes for each per CPU buffer.
 104  */
 105 struct ring_buffer *
 106 ring_buffer_alloc(unsigned long size, unsigned flags);
 107 void ring_buffer_free(struct ring_buffer *buffer);
 108
 109 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
 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 struct ring_buffer_event *
 121 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts);
 122
 123 struct ring_buffer_iter *
 124 ring_buffer_read_start(struct ring_buffer *buffer, int cpu);
 125 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 126
 127 struct ring_buffer_event *
 128 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 129 struct ring_buffer_event *
 130 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 131 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 132 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 133
 134 unsigned long ring_buffer_size(struct ring_buffer *buffer);
 135
 136 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 137 void ring_buffer_reset(struct ring_buffer *buffer);
 138
 139 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 140                          struct ring_buffer *buffer_b, int cpu);
 141
 142 int ring_buffer_empty(struct ring_buffer *buffer);
 143 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 144
 145 void ring_buffer_record_disable(struct ring_buffer *buffer);
 146 void ring_buffer_record_enable(struct ring_buffer *buffer);
 147 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 148 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 149
 150 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 151 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 152 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 153 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 154
 155 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 156 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 157                                       int cpu, u64 *ts);
 158 void ring_buffer_set_clock(struct ring_buffer *buffer,
 159                            u64 (*clock)(void));
 160
 161 size_t ring_buffer_page_len(void *page);
 162
 163
 164 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
 165 void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 166 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 167                           size_t len, int cpu, int full);
 168
 169 struct trace_seq;
 170
 171 int ring_buffer_print_entry_header(struct trace_seq *s);
 172 int ring_buffer_print_page_header(struct trace_seq *s);
 173
 174 enum ring_buffer_flags {
 175         RB_FL_OVERWRITE         = 1 << 0,
 176 };
 177
 178 #endif /* _LINUX_RING_BUFFER_H */