v4.19.13 snapshot.
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
new file mode 100644
index 0000000..0940fda
--- /dev/null
+++ b/include/linux/ring_buffer.h
@@ -0,0 +1,213 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_RING_BUFFER_H
+#define _LINUX_RING_BUFFER_H
+
+#include <linux/mm.h>
+#include <linux/seq_file.h>
+#include <linux/poll.h>
+
+struct ring_buffer;
+struct ring_buffer_iter;
+
+/*
+ * Don't refer to this struct directly, use functions below.
+ */
+struct ring_buffer_event {
+ u32 type_len:5, time_delta:27;
+
+ u32 array[];
+};
+
+/**
+ * enum ring_buffer_type - internal ring buffer types
+ *
+ * @RINGBUF_TYPE_PADDING: Left over page padding or discarded event
+ * If time_delta is 0:
+ * array is ignored
+ * size is variable depending on how much
+ * padding is needed
+ * If time_delta is non zero:
+ * array[0] holds the actual length
+ * size = 4 + length (bytes)
+ *
+ * @RINGBUF_TYPE_TIME_EXTEND: Extend the time delta
+ * array[0] = time delta (28 .. 59)
+ * size = 8 bytes
+ *
+ * @RINGBUF_TYPE_TIME_STAMP: Absolute timestamp
+ * Same format as TIME_EXTEND except that the
+ * value is an absolute timestamp, not a delta
+ * event.time_delta contains bottom 27 bits
+ * array[0] = top (28 .. 59) bits
+ * size = 8 bytes
+ *
+ * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
+ * Data record
+ * If type_len is zero:
+ * array[0] holds the actual length
+ * array[1..(length+3)/4] holds data
+ * size = 4 + length (bytes)
+ * else
+ * length = type_len << 2
+ * array[0..(length+3)/4-1] holds data
+ * size = 4 + length (bytes)
+ */
+enum ring_buffer_type {
+ RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
+ RINGBUF_TYPE_PADDING,
+ RINGBUF_TYPE_TIME_EXTEND,
+ RINGBUF_TYPE_TIME_STAMP,
+};
+
+unsigned ring_buffer_event_length(struct ring_buffer_event *event);
+void *ring_buffer_event_data(struct ring_buffer_event *event);
+u64 ring_buffer_event_time_stamp(struct ring_buffer_event *event);
+
+/*
+ * ring_buffer_discard_commit will remove an event that has not
+ * been committed yet. If this is used, then ring_buffer_unlock_commit
+ * must not be called on the discarded event. This function
+ * will try to remove the event from the ring buffer completely
+ * if another event has not been written after it.
+ *
+ * Example use:
+ *
+ * if (some_condition)
+ * ring_buffer_discard_commit(buffer, event);
+ * else
+ * ring_buffer_unlock_commit(buffer, event);
+ */
+void ring_buffer_discard_commit(struct ring_buffer *buffer,
+ struct ring_buffer_event *event);
+
+/*
+ * size is in bytes for each per CPU buffer.
+ */
+struct ring_buffer *
+__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
+
+/*
+ * Because the ring buffer is generic, if other users of the ring buffer get
+ * traced by ftrace, it can produce lockdep warnings. We need to keep each
+ * ring buffer's lock class separate.
+ */
+#define ring_buffer_alloc(size, flags) \
+({ \
+ static struct lock_class_key __key; \
+ __ring_buffer_alloc((size), (flags), &__key); \
+})
+
+int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full);
+__poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
+ struct file *filp, poll_table *poll_table);
+
+
+#define RING_BUFFER_ALL_CPUS -1
+
+void ring_buffer_free(struct ring_buffer *buffer);
+
+int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
+
+void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
+
+struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
+ unsigned long length);
+int ring_buffer_unlock_commit(struct ring_buffer *buffer,
+ struct ring_buffer_event *event);
+int ring_buffer_write(struct ring_buffer *buffer,
+ unsigned long length, void *data);
+
+void ring_buffer_nest_start(struct ring_buffer *buffer);
+void ring_buffer_nest_end(struct ring_buffer *buffer);
+
+struct ring_buffer_event *
+ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
+ unsigned long *lost_events);
+struct ring_buffer_event *
+ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
+ unsigned long *lost_events);
+
+struct ring_buffer_iter *
+ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
+void ring_buffer_read_prepare_sync(void);
+void ring_buffer_read_start(struct ring_buffer_iter *iter);
+void ring_buffer_read_finish(struct ring_buffer_iter *iter);
+
+struct ring_buffer_event *
+ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
+struct ring_buffer_event *
+ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
+void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
+int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
+
+unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
+
+void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
+void ring_buffer_reset(struct ring_buffer *buffer);
+
+#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
+int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
+ struct ring_buffer *buffer_b, int cpu);
+#else
+static inline int
+ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
+ struct ring_buffer *buffer_b, int cpu)
+{
+ return -ENODEV;
+}
+#endif
+
+bool ring_buffer_empty(struct ring_buffer *buffer);
+bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
+
+void ring_buffer_record_disable(struct ring_buffer *buffer);
+void ring_buffer_record_enable(struct ring_buffer *buffer);
+void ring_buffer_record_off(struct ring_buffer *buffer);
+void ring_buffer_record_on(struct ring_buffer *buffer);
+bool ring_buffer_record_is_on(struct ring_buffer *buffer);
+bool ring_buffer_record_is_set_on(struct ring_buffer *buffer);
+void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
+void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
+
+u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_entries(struct ring_buffer *buffer);
+unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
+unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
+
+u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
+void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
+ int cpu, u64 *ts);
+void ring_buffer_set_clock(struct ring_buffer *buffer,
+ u64 (*clock)(void));
+void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs);
+bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer);
+
+size_t ring_buffer_page_len(void *page);
+
+
+void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
+void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
+int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
+ size_t len, int cpu, int full);
+
+struct trace_seq;
+
+int ring_buffer_print_entry_header(struct trace_seq *s);
+int ring_buffer_print_page_header(struct trace_seq *s);
+
+enum ring_buffer_flags {
+ RB_FL_OVERWRITE = 1 << 0,
+};
+
+#ifdef CONFIG_RING_BUFFER
+int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
+#else
+#define trace_rb_cpu_prepare NULL
+#endif
+
+#endif /* _LINUX_RING_BUFFER_H */