-/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) */
-#include <lib/ringbuffer/frontend.h>
+/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
+ *
+ * lib/ringbuffer/frontend.h
+ *
+ * Ring Buffer Library Synchronization Header (API).
+ *
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * See ring_buffer_frontend.c for more information on wait-free algorithms.
+ */
+
+#ifndef _LIB_RING_BUFFER_FRONTEND_H
+#define _LIB_RING_BUFFER_FRONTEND_H
+
+#include <linux/pipe_fs_i.h>
+#include <linux/rcupdate.h>
+#include <linux/cpumask.h>
+#include <linux/module.h>
+#include <linux/bitops.h>
+#include <linux/splice.h>
+#include <linux/string.h>
+#include <linux/timer.h>
+#include <linux/sched.h>
+#include <linux/cache.h>
+#include <linux/time.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/stat.h>
+#include <linux/cpu.h>
+#include <linux/fs.h>
+
+#include <asm/atomic.h>
+#include <asm/local.h>
+
+/* Internal helpers */
+#include <ringbuffer/frontend_internal.h>
+
+/* Max ring buffer nesting count, see lib_ring_buffer_get_cpu(). */
+#define RING_BUFFER_MAX_NESTING 4
+
+/* Buffer creation/removal and setup operations */
+
+/*
+ * switch_timer_interval is the time interval (in us) to fill sub-buffers with
+ * padding to let readers get those sub-buffers. Used for live streaming.
+ *
+ * read_timer_interval is the time interval (in us) to wake up pending readers.
+ *
+ * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
+ * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
+ * be set to NULL for other backends.
+ */
+
+extern
+struct channel *channel_create(const struct lib_ring_buffer_config *config,
+ const char *name, void *priv,
+ void *buf_addr,
+ size_t subbuf_size, size_t num_subbuf,
+ unsigned int switch_timer_interval,
+ unsigned int read_timer_interval);
+
+/*
+ * channel_destroy returns the private data pointer. It finalizes all channel's
+ * buffers, waits for readers to release all references, and destroys the
+ * channel.
+ */
+extern
+void *channel_destroy(struct channel *chan);
+
+
+/* Buffer read operations */
+
+/*
+ * Iteration on channel cpumask needs to issue a read barrier to match the write
+ * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
+ * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
+ * only performed at channel destruction.
+ */
+#define for_each_channel_cpu(cpu, chan) \
+ for ((cpu) = -1; \
+ ({ (cpu) = cpumask_next(cpu, (chan)->backend.cpumask); \
+ smp_read_barrier_depends(); (cpu) < nr_cpu_ids; });)
+
+extern struct lib_ring_buffer *channel_get_ring_buffer(
+ const struct lib_ring_buffer_config *config,
+ struct channel *chan, int cpu);
+extern int lib_ring_buffer_open_read(struct lib_ring_buffer *buf);
+extern void lib_ring_buffer_release_read(struct lib_ring_buffer *buf);
+
+/*
+ * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
+ */
+extern int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf,
+ unsigned long *consumed,
+ unsigned long *produced);
+extern int lib_ring_buffer_snapshot_sample_positions(
+ struct lib_ring_buffer *buf,
+ unsigned long *consumed,
+ unsigned long *produced);
+extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
+ unsigned long consumed_new);
+
+extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf,
+ unsigned long consumed);
+extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf);
+
+void lib_ring_buffer_set_quiescent_channel(struct channel *chan);
+void lib_ring_buffer_clear_quiescent_channel(struct channel *chan);
+
+/*
+ * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
+ * to read sub-buffers sequentially.
+ */
+static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer *buf)
+{
+ int ret;
+
+ ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
+ &buf->prod_snapshot);
+ if (ret)
+ return ret;
+ ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot);
+ return ret;
+}
+
+static inline void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer *buf)
+{
+ lib_ring_buffer_put_subbuf(buf);
+ lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
+ buf->backend.chan));
+}
+
+extern void channel_reset(struct channel *chan);
+extern void lib_ring_buffer_reset(struct lib_ring_buffer *buf);
+
+static inline
+unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->offset);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return atomic_long_read(&buf->consumed);
+}
+
+/*
+ * Must call lib_ring_buffer_is_finalized before reading counters (memory
+ * ordering enforced with respect to trace teardown).
+ */
+static inline
+int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ int finalized = READ_ONCE(buf->finalized);
+ /*
+ * Read finalized before counters.
+ */
+ smp_rmb();
+ return finalized;
+}
+
+static inline
+int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
+{
+ return chan->finalized;
+}
+
+static inline
+int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
+{
+ return atomic_read(&chan->record_disabled);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_read_data_size(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return subbuffer_get_read_data_size(config, &buf->backend);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_count(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_count);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_overrun(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_overrun);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_full(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_full);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_wrap(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_wrap);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_big(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_big);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_read(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->backend.records_read);
+}
+
+#endif /* _LIB_RING_BUFFER_FRONTEND_H */
projects / lttng-modules.git / blobdiff