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_event_time_delta - return the delta timestamp of the event
  67  * @event: the event to get the delta timestamp of
  68  *
  69  * The delta timestamp is the 27 bit timestamp since the last event.
  70  */
  71 static inline unsigned
  72 ring_buffer_event_time_delta(struct ring_buffer_event *event)
  73 {
  74         return event->time_delta;
  75 }
  76
  77 /*
  78  * ring_buffer_event_discard can discard any event in the ring buffer.
  79  *   it is up to the caller to protect against a reader from
  80  *   consuming it or a writer from wrapping and replacing it.
  81  *
  82  * No external protection is needed if this is called before
  83  * the event is commited. But in that case it would be better to
  84  * use ring_buffer_discard_commit.
  85  *
  86  * Note, if an event that has not been committed is discarded
  87  * with ring_buffer_event_discard, it must still be committed.
  88  */
  89 void ring_buffer_event_discard(struct ring_buffer_event *event);
  90
  91 /*
  92  * ring_buffer_discard_commit will remove an event that has not
  93  *   ben committed yet. If this is used, then ring_buffer_unlock_commit
  94  *   must not be called on the discarded event. This function
  95  *   will try to remove the event from the ring buffer completely
  96  *   if another event has not been written after it.
  97  *
  98  * Example use:
  99  *
 100  *  if (some_condition)
 101  *    ring_buffer_discard_commit(buffer, event);
 102  *  else
 103  *    ring_buffer_unlock_commit(buffer, event);
 104  */
 105 void ring_buffer_discard_commit(struct ring_buffer *buffer,
 106                                 struct ring_buffer_event *event);
 107
 108 /*
 109  * size is in bytes for each per CPU buffer.
 110  */
 111 struct ring_buffer *
 112 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
 113
 114 /*
 115  * Because the ring buffer is generic, if other users of the ring buffer get
 116  * traced by ftrace, it can produce lockdep warnings. We need to keep each
 117  * ring buffer's lock class separate.
 118  */
 119 #define ring_buffer_alloc(size, flags)                  \
 120 ({                                                      \
 121         static struct lock_class_key __key;             \
 122         __ring_buffer_alloc((size), (flags), &__key);   \
 123 })
 124
 125 void ring_buffer_free(struct ring_buffer *buffer);
 126
 127 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
 128
 129 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 130                                                    unsigned long length);
 131 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 132                               struct ring_buffer_event *event);
 133 int ring_buffer_write(struct ring_buffer *buffer,
 134                       unsigned long length, void *data);
 135
 136 struct ring_buffer_event *
 137 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts);
 138 struct ring_buffer_event *
 139 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts);
 140
 141 struct ring_buffer_iter *
 142 ring_buffer_read_start(struct ring_buffer *buffer, int cpu);
 143 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 144
 145 struct ring_buffer_event *
 146 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 147 struct ring_buffer_event *
 148 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 149 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 150 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 151
 152 unsigned long ring_buffer_size(struct ring_buffer *buffer);
 153
 154 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 155 void ring_buffer_reset(struct ring_buffer *buffer);
 156
 157 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 158                          struct ring_buffer *buffer_b, int cpu);
 159
 160 int ring_buffer_empty(struct ring_buffer *buffer);
 161 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 162
 163 void ring_buffer_record_disable(struct ring_buffer *buffer);
 164 void ring_buffer_record_enable(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 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 169 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 170 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 171 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 172 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 173 unsigned long ring_buffer_nmi_dropped_cpu(struct ring_buffer *buffer, int cpu);
 174
 175 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 176 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 177                                       int cpu, u64 *ts);
 178 void ring_buffer_set_clock(struct ring_buffer *buffer,
 179                            u64 (*clock)(void));
 180
 181 size_t ring_buffer_page_len(void *page);
 182
 183
 184 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
 185 void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 186 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 187                           size_t len, int cpu, int full);
 188
 189 struct trace_seq;
 190
 191 int ring_buffer_print_entry_header(struct trace_seq *s);
 192 int ring_buffer_print_page_header(struct trace_seq *s);
 193
 194 enum ring_buffer_flags {
 195         RB_FL_OVERWRITE         = 1 << 0,
 196 };
 197
 198 #endif /* _LINUX_RING_BUFFER_H */