1 /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
3 * 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 <linux/irq_work.h>
17 #include <ringbuffer/config.h>
18 #include <ringbuffer/backend_types.h>
19 #include <lttng/prio_heap.h> /* For per-CPU read-side iterator */
20 #include <lttng/cpuhotplug.h>
23 * A switch is done during tracing or as a final flush after tracing (so it
24 * won't write in the new sub-buffer).
26 enum switch_mode
{ SWITCH_ACTIVE
, SWITCH_FLUSH
};
28 /* channel-level read-side iterator */
30 /* Prio heap of buffers. Lowest timestamps at the top. */
31 struct lttng_ptr_heap heap
; /* Heap of struct lttng_kernel_ring_buffer ptrs */
32 struct list_head empty_head
; /* Empty buffers linked-list head */
33 int read_open
; /* Opened for reading ? */
34 u64 last_qs
; /* Last quiescent state timestamp */
35 u64 last_timestamp
; /* Last timestamp (for WARN_ON) */
36 int last_cpu
; /* Last timestamp cpu */
38 * read() file operation state.
40 unsigned long len_left
;
43 /* channel: collection of per-cpu ring buffers. */
44 struct lttng_kernel_ring_buffer_channel
{
45 atomic_t record_disabled
;
46 unsigned long commit_count_mask
; /*
47 * Commit count mask, removing
48 * the MSBs corresponding to
49 * bits used to represent the
53 struct channel_backend backend
; /* Associated backend */
55 unsigned long switch_timer_interval
; /* Buffer flush (jiffies) */
56 unsigned long read_timer_interval
; /* Reader wakeup (jiffies) */
57 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
58 struct lttng_cpuhp_node cpuhp_prepare
;
59 struct lttng_cpuhp_node cpuhp_online
;
60 struct lttng_cpuhp_node cpuhp_iter_online
;
62 struct notifier_block cpu_hp_notifier
; /* CPU hotplug notifier */
63 struct notifier_block hp_iter_notifier
; /* hotplug iterator notifier */
64 unsigned int cpu_hp_enable
:1; /* Enable CPU hotplug notif. */
65 unsigned int hp_iter_enable
:1; /* Enable hp iter notif. */
67 struct notifier_block tick_nohz_notifier
; /* CPU nohz notifier */
68 wait_queue_head_t read_wait
; /* reader wait queue */
69 wait_queue_head_t hp_wait
; /* CPU hotplug wait queue */
70 struct irq_work wakeup_pending
; /* Pending wakeup irq work */
71 int finalized
; /* Has channel been finalized */
72 struct channel_iter iter
; /* Channel read-side iterator */
73 struct kref ref
; /* Reference count */
76 /* Per-subbuffer commit counters used on the hot path */
77 struct commit_counters_hot
{
78 union v_atomic cc
; /* Commit counter */
79 union v_atomic seq
; /* Consecutive commits */
82 /* Per-subbuffer commit counters used only on cold paths */
83 struct commit_counters_cold
{
84 union v_atomic cc_sb
; /* Incremented _once_ at sb switch */
87 /* Per-buffer read iterator */
88 struct lttng_kernel_ring_buffer_iter
{
89 u64 timestamp
; /* Current record timestamp */
90 size_t header_len
; /* Current record header length */
91 size_t payload_len
; /* Current record payload length */
93 struct list_head empty_node
; /* Linked list of empty buffers */
94 unsigned long consumed
, read_offset
, data_size
;
101 unsigned int allocated
:1;
102 unsigned int read_open
:1; /* Opened for reading ? */
105 /* ring buffer state */
106 struct lttng_kernel_ring_buffer
{
107 /* First 32 bytes cache-hot cacheline */
108 union v_atomic offset
; /* Current offset in the buffer */
109 struct commit_counters_hot
*commit_hot
;
110 /* Commit count per sub-buffer */
111 atomic_long_t consumed
; /*
112 * Current offset in the buffer
113 * standard atomic access (shared)
115 atomic_t record_disabled
;
116 /* End of first 32 bytes cacheline */
117 union v_atomic last_tsc
; /*
118 * Last timestamp written in the buffer.
121 struct lttng_kernel_ring_buffer_backend backend
; /* Associated backend */
123 struct commit_counters_cold
*commit_cold
;
124 /* Commit count per sub-buffer */
126 * timestamp_end per sub-buffer.
127 * Time is sampled by the
128 * switch_*_end() callbacks which
129 * are the last space reservation
130 * performed in the sub-buffer
131 * before it can be fully
132 * committed and delivered. This
133 * time value is then read by
134 * the deliver callback,
135 * performed by the last commit
136 * before the buffer becomes
139 atomic_long_t active_readers
; /*
140 * Active readers count
141 * standard atomic access (shared)
143 /* Dropped records */
144 union v_atomic records_lost_full
; /* Buffer full */
145 union v_atomic records_lost_wrap
; /* Nested wrap-around */
146 union v_atomic records_lost_big
; /* Events too big */
147 union v_atomic records_count
; /* Number of records written */
148 union v_atomic records_overrun
; /* Number of overwritten records */
149 wait_queue_head_t read_wait
; /* reader buffer-level wait queue */
150 wait_queue_head_t write_wait
; /* writer buffer-level wait queue (for metadata only) */
151 struct irq_work wakeup_pending
; /* Pending wakeup irq work */
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 lttng_kernel_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 */
160 unsigned int get_subbuf
:1, /* Sub-buffer being held by reader */
161 switch_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
162 read_timer_enabled
:1, /* Protected by ring_buffer_nohz_lock */
167 void *channel_get_private(struct lttng_kernel_ring_buffer_channel
*chan
)
169 return chan
->backend
.priv
;
172 void lib_ring_buffer_lost_event_too_big(struct lttng_kernel_ring_buffer_channel
*chan
);
175 * Issue warnings and disable channels upon internal error.
176 * Can receive struct lttng_kernel_ring_buffer or struct lttng_kernel_ring_buffer_backend
179 #define CHAN_WARN_ON(c, cond) \
181 struct lttng_kernel_ring_buffer_channel *__chan; \
182 int _____ret = unlikely(cond); \
184 if (__same_type(*(c), struct channel_backend)) \
185 __chan = container_of((void *) (c), \
186 struct lttng_kernel_ring_buffer_channel, \
188 else if (__same_type(*(c), struct lttng_kernel_ring_buffer_channel)) \
189 __chan = (void *) (c); \
192 atomic_inc(&__chan->record_disabled); \
198 #endif /* _LIB_RING_BUFFER_FRONTEND_TYPES_H */