1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Sleepable Read-Copy Update mechanism for mutual exclusion,
* tree variant.
*
* Copyright (C) IBM Corporation, 2017
*
* Author: Paul McKenney <paulmck@linux.ibm.com>
*/
#ifndef _LINUX_SRCU_TREE_H
#define _LINUX_SRCU_TREE_H
#include <linux/rcu_node_tree.h>
#include <linux/completion.h>
struct srcu_node;
struct srcu_struct;
/*
* Per-CPU structure feeding into leaf srcu_node, similar in function
* to rcu_node.
*/
struct srcu_data {
/* Read-side state. */
atomic_long_t srcu_lock_count[2]; /* Locks per CPU. */
atomic_long_t srcu_unlock_count[2]; /* Unlocks per CPU. */
int srcu_nmi_safety; /* NMI-safe srcu_struct structure? */
/* Update-side state. */
spinlock_t __private lock ____cacheline_internodealigned_in_smp;
struct rcu_segcblist srcu_cblist; /* List of callbacks.*/
unsigned long srcu_gp_seq_needed; /* Furthest future GP needed. */
unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */
bool srcu_cblist_invoking; /* Invoking these CBs? */
struct timer_list delay_work; /* Delay for CB invoking */
struct work_struct work; /* Context for CB invoking. */
struct rcu_head srcu_barrier_head; /* For srcu_barrier() use. */
struct srcu_node *mynode; /* Leaf srcu_node. */
unsigned long grpmask; /* Mask for leaf srcu_node */
/* ->srcu_data_have_cbs[]. */
int cpu;
struct srcu_struct *ssp;
};
/*
* Node in SRCU combining tree, similar in function to rcu_data.
*/
struct srcu_node {
spinlock_t __private lock;
unsigned long srcu_have_cbs[4]; /* GP seq for children having CBs, but only */
/* if greater than ->srcu_gp_seq. */
unsigned long srcu_data_have_cbs[4]; /* Which srcu_data structs have CBs for given GP? */
unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */
struct srcu_node *srcu_parent; /* Next up in tree. */
int grplo; /* Least CPU for node. */
int grphi; /* Biggest CPU for node. */
};
/*
* Per-SRCU-domain structure, update-side data linked from srcu_struct.
*/
struct srcu_usage {
struct srcu_node *node; /* Combining tree. */
struct srcu_node *level[RCU_NUM_LVLS + 1];
/* First node at each level. */
int srcu_size_state; /* Small-to-big transition state. */
struct mutex srcu_cb_mutex; /* Serialize CB preparation. */
spinlock_t __private lock; /* Protect counters and size state. */
struct mutex srcu_gp_mutex; /* Serialize GP work. */
unsigned long srcu_gp_seq; /* Grace-period seq #. */
unsigned long srcu_gp_seq_needed; /* Latest gp_seq needed. */
unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */
unsigned long srcu_gp_start; /* Last GP start timestamp (jiffies) */
unsigned long srcu_last_gp_end; /* Last GP end timestamp (ns) */
unsigned long srcu_size_jiffies; /* Current contention-measurement interval. */
unsigned long srcu_n_lock_retries; /* Contention events in current interval. */
unsigned long srcu_n_exp_nodelay; /* # expedited no-delays in current GP phase. */
bool sda_is_static; /* May ->sda be passed to free_percpu()? */
unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */
struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */
struct completion srcu_barrier_completion;
/* Awaken barrier rq at end. */
atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */
/* callback for the barrier */
/* operation. */
unsigned long reschedule_jiffies;
unsigned long reschedule_count;
struct delayed_work work;
struct srcu_struct *srcu_ssp;
};
/*
* Per-SRCU-domain structure, similar in function to rcu_state.
*/
struct srcu_struct {
unsigned int srcu_idx; /* Current rdr array element. */
struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */
struct lockdep_map dep_map;
struct srcu_usage *srcu_sup; /* Update-side data. */
};
// Values for size state variable (->srcu_size_state). Once the state
// has been set to SRCU_SIZE_ALLOC, the grace-period code advances through
// this state machine one step per grace period until the SRCU_SIZE_BIG state
// is reached. Otherwise, the state machine remains in the SRCU_SIZE_SMALL
// state indefinitely.
#define SRCU_SIZE_SMALL 0 // No srcu_node combining tree, ->node == NULL
#define SRCU_SIZE_ALLOC 1 // An srcu_node tree is being allocated, initialized,
// and then referenced by ->node. It will not be used.
#define SRCU_SIZE_WAIT_BARRIER 2 // The srcu_node tree starts being used by everything
// except call_srcu(), especially by srcu_barrier().
// By the end of this state, all CPUs and threads
// are aware of this tree's existence.
#define SRCU_SIZE_WAIT_CALL 3 // The srcu_node tree starts being used by call_srcu().
// By the end of this state, all of the call_srcu()
// invocations that were running on a non-boot CPU
// and using the boot CPU's callback queue will have
// completed.
#define SRCU_SIZE_WAIT_CBS1 4 // Don't trust the ->srcu_have_cbs[] grace-period
#define SRCU_SIZE_WAIT_CBS2 5 // sequence elements or the ->srcu_data_have_cbs[]
#define SRCU_SIZE_WAIT_CBS3 6 // CPU-bitmask elements until all four elements of
#define SRCU_SIZE_WAIT_CBS4 7 // each array have been initialized.
#define SRCU_SIZE_BIG 8 // The srcu_node combining tree is fully initialized
// and all aspects of it are being put to use.
/* Values for state variable (bottom bits of ->srcu_gp_seq). */
#define SRCU_STATE_IDLE 0
#define SRCU_STATE_SCAN1 1
#define SRCU_STATE_SCAN2 2
#define __SRCU_USAGE_INIT(name) \
{ \
.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
.srcu_gp_seq_needed = -1UL, \
.work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0), \
}
#define __SRCU_STRUCT_INIT_COMMON(name, usage_name) \
.srcu_sup = &usage_name, \
__SRCU_DEP_MAP_INIT(name)
#define __SRCU_STRUCT_INIT_MODULE(name, usage_name) \
{ \
__SRCU_STRUCT_INIT_COMMON(name, usage_name) \
}
#define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \
{ \
.sda = &pcpu_name, \
__SRCU_STRUCT_INIT_COMMON(name, usage_name) \
}
/*
* Define and initialize a srcu struct at build time.
* Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it.
*
* Note that although DEFINE_STATIC_SRCU() hides the name from other
* files, the per-CPU variable rules nevertheless require that the
* chosen name be globally unique. These rules also prohibit use of
* DEFINE_STATIC_SRCU() within a function. If these rules are too
* restrictive, declare the srcu_struct manually. For example, in
* each file:
*
* static struct srcu_struct my_srcu;
*
* Then, before the first use of each my_srcu, manually initialize it:
*
* init_srcu_struct(&my_srcu);
*
* See include/linux/percpu-defs.h for the rules on per-CPU variables.
*/
#ifdef MODULE
# define __DEFINE_SRCU(name, is_static) \
static struct srcu_usage name##_srcu_usage = __SRCU_USAGE_INIT(name##_srcu_usage); \
is_static struct srcu_struct name = __SRCU_STRUCT_INIT_MODULE(name, name##_srcu_usage); \
extern struct srcu_struct * const __srcu_struct_##name; \
struct srcu_struct * const __srcu_struct_##name \
__section("___srcu_struct_ptrs") = &name
#else
# define __DEFINE_SRCU(name, is_static) \
static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data); \
static struct srcu_usage name##_srcu_usage = __SRCU_USAGE_INIT(name##_srcu_usage); \
is_static struct srcu_struct name = \
__SRCU_STRUCT_INIT(name, name##_srcu_usage, name##_srcu_data)
#endif
#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)
void synchronize_srcu_expedited(struct srcu_struct *ssp);
void srcu_barrier(struct srcu_struct *ssp);
void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf);
#endif
|
