[lttng-modules.git] / lib / ringbuffer / frontend_types.h

#ifndef _LIB_RING_BUFFER_FRONTEND_TYPES_H
#define _LIB_RING_BUFFER_FRONTEND_TYPES_H

/*
 * lib/ringbuffer/frontend_types.h
 *
 * Ring Buffer Library Synchronization Header (types).
 *
 * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Author:
 *	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * See ring_buffer_frontend.c for more information on wait-free algorithms.
 */

#include <linux/kref.h>
#include <wrapper/ringbuffer/config.h>
#include <wrapper/ringbuffer/backend_types.h>
#include <wrapper/spinlock.h>
#include <lib/prio_heap/lttng_prio_heap.h>	/* For per-CPU read-side iterator */
#include <lttng-cpuhotplug.h>

/*
 * A switch is done during tracing or as a final flush after tracing (so it
 * won't write in the new sub-buffer).
 */
enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };

/* channel-level read-side iterator */
struct channel_iter {
	/* Prio heap of buffers. Lowest timestamps at the top. */
	struct lttng_ptr_heap heap;	/* Heap of struct lib_ring_buffer ptrs */
	struct list_head empty_head;	/* Empty buffers linked-list head */
	int read_open;			/* Opened for reading ? */
	u64 last_qs;			/* Last quiescent state timestamp */
	u64 last_timestamp;		/* Last timestamp (for WARN_ON) */
	int last_cpu;			/* Last timestamp cpu */
	/*
	 * read() file operation state.
	 */
	unsigned long len_left;
};

/* channel: collection of per-cpu ring buffers. */
struct channel {
	atomic_t record_disabled;
	unsigned long commit_count_mask;	/*
						 * Commit count mask, removing
						 * the MSBs corresponding to
						 * bits used to represent the
						 * subbuffer index.
						 */

	struct channel_backend backend;		/* Associated backend */

	unsigned long switch_timer_interval;	/* Buffer flush (jiffies) */
	unsigned long read_timer_interval;	/* Reader wakeup (jiffies) */
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
	struct lttng_cpuhp_node cpuhp_prepare;
	struct lttng_cpuhp_node cpuhp_online;
	struct lttng_cpuhp_node cpuhp_iter_online;
#else
	struct notifier_block cpu_hp_notifier;	/* CPU hotplug notifier */
	struct notifier_block hp_iter_notifier;	/* hotplug iterator notifier */
	unsigned int cpu_hp_enable:1;		/* Enable CPU hotplug notif. */
	unsigned int hp_iter_enable:1;		/* Enable hp iter notif. */
#endif
	struct notifier_block tick_nohz_notifier; /* CPU nohz notifier */
	wait_queue_head_t read_wait;		/* reader wait queue */
	wait_queue_head_t hp_wait;		/* CPU hotplug wait queue */
	int finalized;				/* Has channel been finalized */
	struct channel_iter iter;		/* Channel read-side iterator */
	struct kref ref;			/* Reference count */
};

/* Per-subbuffer commit counters used on the hot path */
struct commit_counters_hot {
	union v_atomic cc;		/* Commit counter */
	union v_atomic seq;		/* Consecutive commits */
};

/* Per-subbuffer commit counters used only on cold paths */
struct commit_counters_cold {
	union v_atomic cc_sb;		/* Incremented _once_ at sb switch */
};

/* Per-buffer read iterator */
struct lib_ring_buffer_iter {
	u64 timestamp;			/* Current record timestamp */
	size_t header_len;		/* Current record header length */
	size_t payload_len;		/* Current record payload length */

	struct list_head empty_node;	/* Linked list of empty buffers */
	unsigned long consumed, read_offset, data_size;
	enum {
		ITER_GET_SUBBUF = 0,
		ITER_TEST_RECORD,
		ITER_NEXT_RECORD,
		ITER_PUT_SUBBUF,
	} state;
	unsigned int allocated:1;
	unsigned int read_open:1;	/* Opened for reading ? */
};

/* ring buffer state */
struct lib_ring_buffer {
	/* First 32 bytes cache-hot cacheline */
	union v_atomic offset;		/* Current offset in the buffer */
	struct commit_counters_hot *commit_hot;
					/* Commit count per sub-buffer */
	atomic_long_t consumed;		/*
					 * Current offset in the buffer
					 * standard atomic access (shared)
					 */
	atomic_t record_disabled;
	/* End of first 32 bytes cacheline */
	union v_atomic last_tsc;	/*
					 * Last timestamp written in the buffer.
					 */

	struct lib_ring_buffer_backend backend;	/* Associated backend */

	struct commit_counters_cold *commit_cold;
					/* Commit count per sub-buffer */
	atomic_long_t active_readers;	/*
					 * Active readers count
					 * standard atomic access (shared)
					 */
					/* Dropped records */
	union v_atomic records_lost_full;	/* Buffer full */
	union v_atomic records_lost_wrap;	/* Nested wrap-around */
	union v_atomic records_lost_big;	/* Events too big */
	union v_atomic records_count;	/* Number of records written */
	union v_atomic records_overrun;	/* Number of overwritten records */
	wait_queue_head_t read_wait;	/* reader buffer-level wait queue */
	wait_queue_head_t write_wait;	/* writer buffer-level wait queue (for metadata only) */
	int finalized;			/* buffer has been finalized */
	struct timer_list switch_timer;	/* timer for periodical switch */
	struct timer_list read_timer;	/* timer for read poll */
	raw_spinlock_t raw_tick_nohz_spinlock;	/* nohz entry lock/trylock */
	struct lib_ring_buffer_iter iter;	/* read-side iterator */
	unsigned long get_subbuf_consumed;	/* Read-side consumed */
	unsigned long prod_snapshot;	/* Producer count snapshot */
	unsigned long cons_snapshot;	/* Consumer count snapshot */
	unsigned int get_subbuf:1,	/* Sub-buffer being held by reader */
		switch_timer_enabled:1,	/* Protected by ring_buffer_nohz_lock */
		read_timer_enabled:1,	/* Protected by ring_buffer_nohz_lock */
		quiescent:1;
};

static inline
void *channel_get_private(struct channel *chan)
{
	return chan->backend.priv;
}

void lib_ring_buffer_lost_event_too_big(struct channel *chan);

/*
 * Issue warnings and disable channels upon internal error.
 * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
 * parameters.
 */
#define CHAN_WARN_ON(c, cond)						\
	({								\
		struct channel *__chan;					\
		int _____ret = unlikely(cond);				\
		if (_____ret) {						\
			if (__same_type(*(c), struct channel_backend))	\
				__chan = container_of((void *) (c),	\
							struct channel, \
							backend);	\
			else if (__same_type(*(c), struct channel))	\
				__chan = (void *) (c);			\
			else						\
				BUG_ON(1);				\
			atomic_inc(&__chan->record_disabled);		\
			WARN_ON(1);					\
		}							\
		_____ret;						\
	})

#endif /* _LIB_RING_BUFFER_FRONTEND_TYPES_H */
Commit	Line	Data
886d51a3 MD	1	#ifndef _LIB_RING_BUFFER_FRONTEND_TYPES_H
886d51a3 MD	2	#define _LIB_RING_BUFFER_FRONTEND_TYPES_H
f3bc08c5 MD	3
f3bc08c5 MD	4	/*
886d51a3	5	* lib/ringbuffer/frontend_types.h
f3bc08c5 MD	6	*
	7	* Ring Buffer Library Synchronization Header (types).
	8	*
886d51a3 MD	9	* Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	10	*
	11	* This library is free software; you can redistribute it and/or
	12	* modify it under the terms of the GNU Lesser General Public
	13	* License as published by the Free Software Foundation; only
	14	* version 2.1 of the License.
	15	*
	16	* This library is distributed in the hope that it will be useful,
	17	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	18	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	19	* Lesser General Public License for more details.
	20	*
	21	* You should have received a copy of the GNU Lesser General Public
	22	* License along with this library; if not, write to the Free Software
	23	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	24	*
f3bc08c5 MD	25	* Author:
	26	* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	27	*
	28	* See ring_buffer_frontend.c for more information on wait-free algorithms.
f3bc08c5 MD	29	*/
f3bc08c5 MD	30
f40270ad	31	#include <linux/kref.h>
5671a661 MD	32	#include <wrapper/ringbuffer/config.h>
	33	#include <wrapper/ringbuffer/backend_types.h>
	34	#include <wrapper/spinlock.h>
	35	#include <lib/prio_heap/lttng_prio_heap.h> /* For per-CPU read-side iterator */
1e367326	36	#include <lttng-cpuhotplug.h>
f3bc08c5 MD	37
	38	/*
	39	* A switch is done during tracing or as a final flush after tracing (so it
	40	* won't write in the new sub-buffer).
	41	*/
	42	enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };
	43
	44	/* channel-level read-side iterator */
	45	struct channel_iter {
	46	/* Prio heap of buffers. Lowest timestamps at the top. */
a88db018	47	struct lttng_ptr_heap heap; /* Heap of struct lib_ring_buffer ptrs */
f3bc08c5 MD	48	struct list_head empty_head; /* Empty buffers linked-list head */
	49	int read_open; /* Opened for reading ? */
	50	u64 last_qs; /* Last quiescent state timestamp */
	51	u64 last_timestamp; /* Last timestamp (for WARN_ON) */
	52	int last_cpu; /* Last timestamp cpu */
	53	/*
	54	* read() file operation state.
	55	*/
	56	unsigned long len_left;
	57	};
	58
	59	/* channel: collection of per-cpu ring buffers. */
	60	struct channel {
	61	atomic_t record_disabled;
	62	unsigned long commit_count_mask; /*
	63	* Commit count mask, removing
	64	* the MSBs corresponding to
	65	* bits used to represent the
	66	* subbuffer index.
	67	*/
	68
	69	struct channel_backend backend; /* Associated backend */
	70
	71	unsigned long switch_timer_interval; /* Buffer flush (jiffies) */
	72	unsigned long read_timer_interval; /* Reader wakeup (jiffies) */
1e367326 MD	73	#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
	74	struct lttng_cpuhp_node cpuhp_prepare;
	75	struct lttng_cpuhp_node cpuhp_online;
	76	struct lttng_cpuhp_node cpuhp_iter_online;
	77	#else
f3bc08c5	78	struct notifier_block cpu_hp_notifier; /* CPU hotplug notifier */
f3bc08c5	79	struct notifier_block hp_iter_notifier; /* hotplug iterator notifier */
9cccf98a MD	80	unsigned int cpu_hp_enable:1; /* Enable CPU hotplug notif. */
9cccf98a MD	81	unsigned int hp_iter_enable:1; /* Enable hp iter notif. */
1e367326 MD	82	#endif
1e367326 MD	83	struct notifier_block tick_nohz_notifier; /* CPU nohz notifier */
f3bc08c5	84	wait_queue_head_t read_wait; /* reader wait queue */
24cedcfe MD	85	wait_queue_head_t hp_wait; /* CPU hotplug wait queue */
24cedcfe MD	86	int finalized; /* Has channel been finalized */
f3bc08c5	87	struct channel_iter iter; /* Channel read-side iterator */
f40270ad	88	struct kref ref; /* Reference count */
f3bc08c5 MD	89	};
	90
	91	/* Per-subbuffer commit counters used on the hot path */
	92	struct commit_counters_hot {
	93	union v_atomic cc; /* Commit counter */
	94	union v_atomic seq; /* Consecutive commits */
	95	};
	96
	97	/* Per-subbuffer commit counters used only on cold paths */
	98	struct commit_counters_cold {
	99	union v_atomic cc_sb; /* Incremented _once_ at sb switch */
	100	};
	101
	102	/* Per-buffer read iterator */
	103	struct lib_ring_buffer_iter {
	104	u64 timestamp; /* Current record timestamp */
	105	size_t header_len; /* Current record header length */
	106	size_t payload_len; /* Current record payload length */
	107
	108	struct list_head empty_node; /* Linked list of empty buffers */
	109	unsigned long consumed, read_offset, data_size;
	110	enum {
	111	ITER_GET_SUBBUF = 0,
	112	ITER_TEST_RECORD,
	113	ITER_NEXT_RECORD,
	114	ITER_PUT_SUBBUF,
	115	} state;
9cccf98a MD	116	unsigned int allocated:1;
9cccf98a MD	117	unsigned int read_open:1; /* Opened for reading ? */
f3bc08c5 MD	118	};
	119
	120	/* ring buffer state */
	121	struct lib_ring_buffer {
	122	/* First 32 bytes cache-hot cacheline */
	123	union v_atomic offset; /* Current offset in the buffer */
	124	struct commit_counters_hot *commit_hot;
	125	/* Commit count per sub-buffer */
	126	atomic_long_t consumed; /*
	127	* Current offset in the buffer
	128	* standard atomic access (shared)
	129	*/
	130	atomic_t record_disabled;
	131	/* End of first 32 bytes cacheline */
	132	union v_atomic last_tsc; /*
	133	* Last timestamp written in the buffer.
	134	*/
	135
	136	struct lib_ring_buffer_backend backend; /* Associated backend */
	137
	138	struct commit_counters_cold *commit_cold;
	139	/* Commit count per sub-buffer */
	140	atomic_long_t active_readers; /*
	141	* Active readers count
	142	* standard atomic access (shared)
	143	*/
	144	/* Dropped records */
	145	union v_atomic records_lost_full; /* Buffer full */
	146	union v_atomic records_lost_wrap; /* Nested wrap-around */
	147	union v_atomic records_lost_big; /* Events too big */
	148	union v_atomic records_count; /* Number of records written */
	149	union v_atomic records_overrun; /* Number of overwritten records */
	150	wait_queue_head_t read_wait; /* reader buffer-level wait queue */
71c1d843	151	wait_queue_head_t write_wait; /* writer buffer-level wait queue (for metadata only) */
f3bc08c5 MD	152	int finalized; /* buffer has been finalized */
	153	struct timer_list switch_timer; /* timer for periodical switch */
	154	struct timer_list read_timer; /* timer for read poll */
	155	raw_spinlock_t raw_tick_nohz_spinlock; /* nohz entry lock/trylock */
	156	struct lib_ring_buffer_iter iter; /* read-side iterator */
	157	unsigned long get_subbuf_consumed; /* Read-side consumed */
	158	unsigned long prod_snapshot; /* Producer count snapshot */
	159	unsigned long cons_snapshot; /* Consumer count snapshot */
9cccf98a MD	160	unsigned int get_subbuf:1, /* Sub-buffer being held by reader */
9cccf98a MD	161	switch_timer_enabled:1, /* Protected by ring_buffer_nohz_lock */
64af2437 MD	162	read_timer_enabled:1, /* Protected by ring_buffer_nohz_lock */
64af2437 MD	163	quiescent:1;
f3bc08c5 MD	164	};
f3bc08c5 MD	165
9115fbdc MD	166	static inline
	167	void channel_get_private(struct channel chan)
	168	{
	169	return chan->backend.priv;
	170	}
	171
d7e74017 MD	172	void lib_ring_buffer_lost_event_too_big(struct channel *chan);
d7e74017 MD	173
f3bc08c5 MD	174	/*
	175	* Issue warnings and disable channels upon internal error.
	176	* Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
	177	* parameters.
	178	*/
	179	#define CHAN_WARN_ON(c, cond) \
	180	({ \
	181	struct channel *__chan; \
	182	int _____ret = unlikely(cond); \
	183	if (_____ret) { \
	184	if (__same_type(*(c), struct channel_backend)) \
	185	__chan = container_of((void *) (c), \
	186	struct channel, \
	187	backend); \
	188	else if (__same_type(*(c), struct channel)) \
	189	__chan = (void *) (c); \
	190	else \
	191	BUG_ON(1); \
	192	atomic_inc(&__chan->record_disabled); \
	193	WARN_ON(1); \
	194	} \
	195	_____ret; \
	196	})
	197
886d51a3	198	#endif /* _LIB_RING_BUFFER_FRONTEND_TYPES_H */