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 */ 199