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8c366db0 | 1 | /* SPDX-License-Identifier: GPL-2.0+ */ |
d8be8173 PM |
2 | /* |
3 | * Sleepable Read-Copy Update mechanism for mutual exclusion, | |
4 | * tree variant. | |
5 | * | |
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6 | * Copyright (C) IBM Corporation, 2017 |
7 | * | |
8c366db0 | 8 | * Author: Paul McKenney <paulmck@linux.ibm.com> |
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9 | */ |
10 | ||
11 | #ifndef _LINUX_SRCU_TREE_H | |
12 | #define _LINUX_SRCU_TREE_H | |
13 | ||
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14 | #include <linux/rcu_node_tree.h> |
15 | #include <linux/completion.h> | |
16 | ||
17 | struct srcu_node; | |
18 | struct srcu_struct; | |
19 | ||
20 | /* | |
21 | * Per-CPU structure feeding into leaf srcu_node, similar in function | |
22 | * to rcu_node. | |
23 | */ | |
24 | struct srcu_data { | |
25 | /* Read-side state. */ | |
5d0f5953 PM |
26 | atomic_long_t srcu_lock_count[2]; /* Locks per CPU. */ |
27 | atomic_long_t srcu_unlock_count[2]; /* Unlocks per CPU. */ | |
27120e7d | 28 | int srcu_nmi_safety; /* NMI-safe srcu_struct structure? */ |
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29 | |
30 | /* Update-side state. */ | |
d6331980 | 31 | spinlock_t __private lock ____cacheline_internodealigned_in_smp; |
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32 | struct rcu_segcblist srcu_cblist; /* List of callbacks.*/ |
33 | unsigned long srcu_gp_seq_needed; /* Furthest future GP needed. */ | |
1e9a038b | 34 | unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ |
da915ad5 | 35 | bool srcu_cblist_invoking; /* Invoking these CBs? */ |
e81baf4c SAS |
36 | struct timer_list delay_work; /* Delay for CB invoking */ |
37 | struct work_struct work; /* Context for CB invoking. */ | |
da915ad5 PM |
38 | struct rcu_head srcu_barrier_head; /* For srcu_barrier() use. */ |
39 | struct srcu_node *mynode; /* Leaf srcu_node. */ | |
c7e88067 PM |
40 | unsigned long grpmask; /* Mask for leaf srcu_node */ |
41 | /* ->srcu_data_have_cbs[]. */ | |
da915ad5 | 42 | int cpu; |
aacb5d91 | 43 | struct srcu_struct *ssp; |
d8be8173 PM |
44 | }; |
45 | ||
da915ad5 PM |
46 | /* |
47 | * Node in SRCU combining tree, similar in function to rcu_data. | |
48 | */ | |
49 | struct srcu_node { | |
d6331980 | 50 | spinlock_t __private lock; |
95ebe80d | 51 | unsigned long srcu_have_cbs[4]; /* GP seq for children having CBs, but only */ |
aa5210f5 | 52 | /* if greater than ->srcu_gp_seq. */ |
95ebe80d | 53 | unsigned long srcu_data_have_cbs[4]; /* Which srcu_data structs have CBs for given GP? */ |
1e9a038b | 54 | unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ |
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55 | struct srcu_node *srcu_parent; /* Next up in tree. */ |
56 | int grplo; /* Least CPU for node. */ | |
57 | int grphi; /* Biggest CPU for node. */ | |
58 | }; | |
59 | ||
60 | /* | |
95433f72 | 61 | * Per-SRCU-domain structure, update-side data linked from srcu_struct. |
da915ad5 | 62 | */ |
95433f72 | 63 | struct srcu_usage { |
2ec30311 | 64 | struct srcu_node *node; /* Combining tree. */ |
da915ad5 PM |
65 | struct srcu_node *level[RCU_NUM_LVLS + 1]; |
66 | /* First node at each level. */ | |
994f7068 | 67 | int srcu_size_state; /* Small-to-big transition state. */ |
da915ad5 | 68 | struct mutex srcu_cb_mutex; /* Serialize CB preparation. */ |
994f7068 | 69 | spinlock_t __private lock; /* Protect counters and size state. */ |
da915ad5 | 70 | struct mutex srcu_gp_mutex; /* Serialize GP work. */ |
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71 | unsigned long srcu_gp_seq; /* Grace-period seq #. */ |
72 | unsigned long srcu_gp_seq_needed; /* Latest gp_seq needed. */ | |
1e9a038b | 73 | unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ |
282d8998 | 74 | unsigned long srcu_gp_start; /* Last GP start timestamp (jiffies) */ |
22607d66 | 75 | unsigned long srcu_last_gp_end; /* Last GP end timestamp (ns) */ |
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76 | unsigned long srcu_size_jiffies; /* Current contention-measurement interval. */ |
77 | unsigned long srcu_n_lock_retries; /* Contention events in current interval. */ | |
282d8998 | 78 | unsigned long srcu_n_exp_nodelay; /* # expedited no-delays in current GP phase. */ |
46470cf8 | 79 | bool sda_is_static; /* May ->sda be passed to free_percpu()? */ |
da915ad5 PM |
80 | unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */ |
81 | struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */ | |
82 | struct completion srcu_barrier_completion; | |
83 | /* Awaken barrier rq at end. */ | |
84 | atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */ | |
85 | /* callback for the barrier */ | |
86 | /* operation. */ | |
282d8998 PM |
87 | unsigned long reschedule_jiffies; |
88 | unsigned long reschedule_count; | |
d8be8173 | 89 | struct delayed_work work; |
fd1b3f8e | 90 | struct srcu_struct *srcu_ssp; |
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91 | }; |
92 | ||
da915ad5 PM |
93 | /* |
94 | * Per-SRCU-domain structure, similar in function to rcu_state. | |
95 | */ | |
d8be8173 | 96 | struct srcu_struct { |
da915ad5 | 97 | unsigned int srcu_idx; /* Current rdr array element. */ |
da915ad5 | 98 | struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ |
d8be8173 | 99 | struct lockdep_map dep_map; |
95433f72 | 100 | struct srcu_usage *srcu_sup; /* Update-side data. */ |
d8be8173 PM |
101 | }; |
102 | ||
e15a1930 PL |
103 | // Values for size state variable (->srcu_size_state). Once the state |
104 | // has been set to SRCU_SIZE_ALLOC, the grace-period code advances through | |
105 | // this state machine one step per grace period until the SRCU_SIZE_BIG state | |
106 | // is reached. Otherwise, the state machine remains in the SRCU_SIZE_SMALL | |
107 | // state indefinitely. | |
108 | #define SRCU_SIZE_SMALL 0 // No srcu_node combining tree, ->node == NULL | |
109 | #define SRCU_SIZE_ALLOC 1 // An srcu_node tree is being allocated, initialized, | |
110 | // and then referenced by ->node. It will not be used. | |
111 | #define SRCU_SIZE_WAIT_BARRIER 2 // The srcu_node tree starts being used by everything | |
112 | // except call_srcu(), especially by srcu_barrier(). | |
113 | // By the end of this state, all CPUs and threads | |
114 | // are aware of this tree's existence. | |
115 | #define SRCU_SIZE_WAIT_CALL 3 // The srcu_node tree starts being used by call_srcu(). | |
116 | // By the end of this state, all of the call_srcu() | |
117 | // invocations that were running on a non-boot CPU | |
118 | // and using the boot CPU's callback queue will have | |
119 | // completed. | |
120 | #define SRCU_SIZE_WAIT_CBS1 4 // Don't trust the ->srcu_have_cbs[] grace-period | |
121 | #define SRCU_SIZE_WAIT_CBS2 5 // sequence elements or the ->srcu_data_have_cbs[] | |
122 | #define SRCU_SIZE_WAIT_CBS3 6 // CPU-bitmask elements until all four elements of | |
123 | #define SRCU_SIZE_WAIT_CBS4 7 // each array have been initialized. | |
124 | #define SRCU_SIZE_BIG 8 // The srcu_node combining tree is fully initialized | |
125 | // and all aspects of it are being put to use. | |
994f7068 | 126 | |
da915ad5 | 127 | /* Values for state variable (bottom bits of ->srcu_gp_seq). */ |
d8be8173 PM |
128 | #define SRCU_STATE_IDLE 0 |
129 | #define SRCU_STATE_SCAN1 1 | |
130 | #define SRCU_STATE_SCAN2 2 | |
131 | ||
03200b5c PM |
132 | #define __SRCU_USAGE_INIT(name) \ |
133 | { \ | |
134 | .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ | |
3e67cb8a | 135 | .srcu_gp_seq_needed = -1UL, \ |
fd1b3f8e | 136 | .work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0), \ |
03200b5c PM |
137 | } |
138 | ||
139 | #define __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ | |
95433f72 | 140 | .srcu_sup = &usage_name, \ |
f4d01a25 PM |
141 | __SRCU_DEP_MAP_INIT(name) |
142 | ||
95433f72 | 143 | #define __SRCU_STRUCT_INIT_MODULE(name, usage_name) \ |
f4d01a25 | 144 | { \ |
95433f72 | 145 | __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ |
e0fcba9a | 146 | } |
d8be8173 | 147 | |
95433f72 | 148 | #define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name) \ |
f4d01a25 PM |
149 | { \ |
150 | .sda = &pcpu_name, \ | |
95433f72 | 151 | __SRCU_STRUCT_INIT_COMMON(name, usage_name) \ |
e0fcba9a | 152 | } |
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153 | |
154 | /* | |
155 | * Define and initialize a srcu struct at build time. | |
156 | * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it. | |
157 | * | |
158 | * Note that although DEFINE_STATIC_SRCU() hides the name from other | |
159 | * files, the per-CPU variable rules nevertheless require that the | |
160 | * chosen name be globally unique. These rules also prohibit use of | |
161 | * DEFINE_STATIC_SRCU() within a function. If these rules are too | |
162 | * restrictive, declare the srcu_struct manually. For example, in | |
163 | * each file: | |
164 | * | |
165 | * static struct srcu_struct my_srcu; | |
166 | * | |
167 | * Then, before the first use of each my_srcu, manually initialize it: | |
168 | * | |
169 | * init_srcu_struct(&my_srcu); | |
170 | * | |
171 | * See include/linux/percpu-defs.h for the rules on per-CPU variables. | |
172 | */ | |
fe15b50c | 173 | #ifdef MODULE |
3e67cb8a | 174 | # define __DEFINE_SRCU(name, is_static) \ |
03200b5c | 175 | static struct srcu_usage name##_srcu_usage = __SRCU_USAGE_INIT(name##_srcu_usage); \ |
95433f72 | 176 | is_static struct srcu_struct name = __SRCU_STRUCT_INIT_MODULE(name, name##_srcu_usage); \ |
3e67cb8a PM |
177 | extern struct srcu_struct * const __srcu_struct_##name; \ |
178 | struct srcu_struct * const __srcu_struct_##name \ | |
fe15b50c PM |
179 | __section("___srcu_struct_ptrs") = &name |
180 | #else | |
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181 | # define __DEFINE_SRCU(name, is_static) \ |
182 | static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data); \ | |
03200b5c | 183 | static struct srcu_usage name##_srcu_usage = __SRCU_USAGE_INIT(name##_srcu_usage); \ |
3e67cb8a | 184 | is_static struct srcu_struct name = \ |
95433f72 | 185 | __SRCU_STRUCT_INIT(name, name##_srcu_usage, name##_srcu_data) |
fe15b50c | 186 | #endif |
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187 | #define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */) |
188 | #define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static) | |
189 | ||
aacb5d91 PM |
190 | void synchronize_srcu_expedited(struct srcu_struct *ssp); |
191 | void srcu_barrier(struct srcu_struct *ssp); | |
192 | void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); | |
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193 | |
194 | #endif |