1 /* SPDX-License-Identifier: (GPL-2.0 OR LGPL-2.1)
3 * lib/ringbuffer/frontend_types.h
5 * Ring Buffer Library Synchronization Header (types).
7 * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 * See ring_buffer_frontend.c for more information on wait-free algorithms.
12 #ifndef _LIB_RING_BUFFER_FRONTEND_TYPES_H
13 #define _LIB_RING_BUFFER_FRONTEND_TYPES_H
15 #include <linux/kref.h>
16 #include <wrapper/ringbuffer/config.h>
17 #include <wrapper/ringbuffer/backend_types.h>
18 #include <lib/prio_heap/lttng_prio_heap.h> /* For per-CPU read-side iterator */
19 #include <lttng-cpuhotplug.h>
22 * A switch is done during tracing or as a final flush after tracing (so it
23 * won't write in the new sub-buffer).
25 enum switch_mode
{ SWITCH_ACTIVE
, SWITCH_FLUSH
};
27 /* channel-level read-side iterator */
29 /* Prio heap of buffers. Lowest timestamps at the top. */
30 struct lttng_ptr_heap heap
; /* Heap of struct lib_ring_buffer ptrs */
31 struct list_head empty_head
; /* Empty buffers linked-list head */
32 int read_open
; /* Opened for reading ? */
33 u64 last_qs
; /* Last quiescent state timestamp */
34 u64 last_timestamp
; /* Last timestamp (for WARN_ON) */
35 int last_cpu
; /* Last timestamp cpu */
37 * read() file operation state.
39 unsigned long len_left
;
42 /* channel: collection of per-cpu ring buffers. */
44 atomic_t record_disabled
;
45 unsigned long commit_count_mask
; /*
46 * Commit count mask, removing
47 * the MSBs corresponding to
48 * bits used to represent the
52 struct channel_backend backend
; /* Associated backend */
54 unsigned long switch_timer_interval
; /* Buffer flush (jiffies) */
55 unsigned long read_timer_interval
; /* Reader wakeup (jiffies) */
56 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
57 struct lttng_cpuhp_node cpuhp_prepare
;
58 struct lttng_cpuhp_node cpuhp_online
;
59 struct lttng_cpuhp_node cpuhp_iter_online
;
61 struct notifier_block cpu_hp_notifier
; /* CPU hotplug notifier */
62 struct notifier_block hp_iter_notifier
; /* hotplug iterator notifier */
63 unsigned int cpu_hp_enable
:1; /* Enable CPU hotplug notif. */
64 unsigned int hp_iter_enable
:1; /* Enable hp iter notif. */
66 struct notifier_block tick_nohz_notifier
; /* CPU nohz notifier */
67 wait_queue_head_t read_wait
; /* reader wait queue */
68 wait_queue_head_t hp_wait
; /* CPU hotplug wait queue */
69 int finalized
; /* Has channel been finalized */
70 struct channel_iter iter
; /* Channel read-side iterator */
71 struct kref ref
; /* Reference count */
74 /* Per-subbuffer commit counters used on the hot path */
75 struct commit_counters_hot
{
76 union v_atomic cc
; /* Commit counter */
77 union v_atomic seq
; /* Consecutive commits */
80 /* Per-subbuffer commit counters used only on cold paths */
81 struct commit_counters_cold
{
82 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
85 /* Per-buffer read iterator */
86 struct lib_ring_buffer_iter
{
87 u64 timestamp
; /* Current record timestamp */
88 size_t header_len
; /* Current record header length */
89 size_t payload_len
; /* Current record payload length */
91 struct list_head empty_node
; /* Linked list of empty buffers */
92 unsigned long consumed
, read_offset
, data_size
;
99 unsigned int allocated
:1;
100 unsigned int read_open
:1; /* Opened for reading ? */
103 /* ring buffer state */
104 struct lib_ring_buffer
{
105 /* First 32 bytes cache-hot cacheline */
106 union v_atomic offset
; /* Current offset in the buffer */
107 struct commit_counters_hot
*commit_hot
;
108 /* Commit count per sub-buffer */
109 atomic_long_t consumed
; /*
110 * Current offset in the buffer
111 * standard atomic access (shared)
113 atomic_t record_disabled
;
114 /* End of first 32 bytes cacheline */
115 union v_atomic last_tsc
; /*
116 * Last timestamp written in the buffer.
119 struct lib_ring_buffer_backend backend
; /* Associated backend */
121 struct commit_counters_cold
*commit_cold
;
122 /* Commit count per sub-buffer */
124 * timestamp_end per sub-buffer.
125 * Time is sampled by the
126 * switch_*_end() callbacks which
127 * are the last space reservation
128 * performed in the sub-buffer
129 * before it can be fully
130 * committed and delivered. This
131 * time value is then read by
132 * the deliver callback,
133 * performed by the last commit
134 * before the buffer becomes
137 atomic_long_t active_readers
; /*
138 * Active readers count
139 * standard atomic access (shared)
141 /* Dropped records */
142 union v_atomic records_lost_full
; /* Buffer full */
143 union v_atomic records_lost_wrap
; /* Nested wrap-around */
144 union v_atomic records_lost_big
; /* Events too big */
145 union v_atomic records_count
; /* Number of records written */
146 union v_atomic records_overrun
; /* Number of overwritten records */
147 wait_queue_head_t read_wait
; /* reader buffer-level wait queue */
148 wait_queue_head_t write_wait
; /* writer buffer-level wait queue (for metadata only) */
149 int finalized
; /* buffer has been finalized */
150 struct timer_list switch_timer
; /* timer for periodical switch */
151 struct timer_list read_timer
; /* timer for read poll */
152 raw_spinlock_t raw_tick_nohz_spinlock
; /* nohz entry lock/trylock */
153 struct lib_ring_buffer_iter iter
; /* read-side iterator */
154 unsigned long get_subbuf_consumed
; /* Read-side consumed */
155 unsigned long prod_snapshot
; /* Producer count snapshot */
156 unsigned long cons_snapshot
; /* Consumer count snapshot */
157 unsigned int get_subbuf
:1, /* Sub-buffer being held by reader */
158 switch_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
159 read_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
164 void *channel_get_private(struct channel
*chan
)
166 return chan
->backend
.priv
;
169 void lib_ring_buffer_lost_event_too_big(struct channel
*chan
);
172 * Issue warnings and disable channels upon internal error.
173 * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
176 #define CHAN_WARN_ON(c, cond) \
178 struct channel *__chan; \
179 int _____ret = unlikely(cond); \
181 if (__same_type(*(c), struct channel_backend)) \
182 __chan = container_of((void *) (c), \
185 else if (__same_type(*(c), struct channel)) \
186 __chan = (void *) (c); \
189 atomic_inc(&__chan->record_disabled); \
195 #endif /* _LIB_RING_BUFFER_FRONTEND_TYPES_H */