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_discard_commit will remove an event that has not
  79  *   ben committed yet. If this is used, then ring_buffer_unlock_commit
  80  *   must not be called on the discarded event. This function
  81  *   will try to remove the event from the ring buffer completely
  82  *   if another event has not been written after it.
  83  *
  84  * Example use:
  85  *
  86  *  if (some_condition)
  87  *    ring_buffer_discard_commit(buffer, event);
  88  *  else
  89  *    ring_buffer_unlock_commit(buffer, event);
  90  */
  91 void ring_buffer_discard_commit(struct ring_buffer *buffer,
  92                                 struct ring_buffer_event *event);
  93
  94 /*
  95  * size is in bytes for each per CPU buffer.
  96  */
  97 struct ring_buffer *
  98 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
  99
 100 /*
 101  * Because the ring buffer is generic, if other users of the ring buffer get
 102  * traced by ftrace, it can produce lockdep warnings. We need to keep each
 103  * ring buffer's lock class separate.
 104  */
 105 #define ring_buffer_alloc(size, flags)                  \
 106 ({                                                      \
 107         static struct lock_class_key __key;             \
 108         __ring_buffer_alloc((size), (flags), &__key);   \
 109 })
 110
 111 void ring_buffer_free(struct ring_buffer *buffer);
 112
 113 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
 114
 115 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 116                                                    unsigned long length);
 117 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 118                               struct ring_buffer_event *event);
 119 int ring_buffer_write(struct ring_buffer *buffer,
 120                       unsigned long length, void *data);
 121
 122 struct ring_buffer_event *
 123 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts);
 124 struct ring_buffer_event *
 125 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts);
 126
 127 struct ring_buffer_iter *
 128 ring_buffer_read_start(struct ring_buffer *buffer, int cpu);
 129 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 130
 131 struct ring_buffer_event *
 132 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 133 struct ring_buffer_event *
 134 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 135 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 136 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 137
 138 unsigned long ring_buffer_size(struct ring_buffer *buffer);
 139
 140 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 141 void ring_buffer_reset(struct ring_buffer *buffer);
 142
 143 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 144 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 145                          struct ring_buffer *buffer_b, int cpu);
 146 #else
 147 static inline int
 148 ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 149                      struct ring_buffer *buffer_b, int cpu)
 150 {
 151         return -ENODEV;
 152 }
 153 #endif
 154
 155 int ring_buffer_empty(struct ring_buffer *buffer);
 156 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 157
 158 void ring_buffer_record_disable(struct ring_buffer *buffer);
 159 void ring_buffer_record_enable(struct ring_buffer *buffer);
 160 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 161 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 162
 163 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 164 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 165 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 166 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 167 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 168
 169 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 170 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 171                                       int cpu, u64 *ts);
 172 void ring_buffer_set_clock(struct ring_buffer *buffer,
 173                            u64 (*clock)(void));
 174
 175 size_t ring_buffer_page_len(void *page);
 176
 177
 178 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
 179 void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 180 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 181                           size_t len, int cpu, int full);
 182
 183 struct trace_seq;
 184
 185 int ring_buffer_print_entry_header(struct trace_seq *s);
 186 int ring_buffer_print_page_header(struct trace_seq *s);
 187
 188 enum ring_buffer_flags {
 189         RB_FL_OVERWRITE         = 1 << 0,
 190 };
 191
 192 #endif /* _LINUX_RING_BUFFER_H */