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1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * Sleepable Read-Copy Update mechanism for mutual exclusion,
4 * tiny variant.
5 *
6 * Copyright (C) IBM Corporation, 2017
7 *
8 * Author: Paul McKenney <paulmck@linux.ibm.com>
9 */
10
11#ifndef _LINUX_SRCU_TINY_H
12#define _LINUX_SRCU_TINY_H
13
14#include <linux/swait.h>
15
16struct srcu_struct {
17 short srcu_lock_nesting[2]; /* srcu_read_lock() nesting depth. */
18 short srcu_idx; /* Current reader array element. */
19 u8 srcu_gp_running; /* GP workqueue running? */
20 u8 srcu_gp_waiting; /* GP waiting for readers? */
21 struct swait_queue_head srcu_wq;
22 /* Last srcu_read_unlock() wakes GP. */
23 struct rcu_head *srcu_cb_head; /* Pending callbacks: Head. */
24 struct rcu_head **srcu_cb_tail; /* Pending callbacks: Tail. */
25 struct work_struct srcu_work; /* For driving grace periods. */
26#ifdef CONFIG_DEBUG_LOCK_ALLOC
27 struct lockdep_map dep_map;
28#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
29};
30
31void srcu_drive_gp(struct work_struct *wp);
32
33#define __SRCU_STRUCT_INIT(name, __ignored) \
34{ \
35 .srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \
36 .srcu_cb_tail = &name.srcu_cb_head, \
37 .srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp), \
38 __SRCU_DEP_MAP_INIT(name) \
39}
40
41/*
42 * This odd _STATIC_ arrangement is needed for API compatibility with
43 * Tree SRCU, which needs some per-CPU data.
44 */
45#define DEFINE_SRCU(name) \
46 struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
47#define DEFINE_STATIC_SRCU(name) \
48 static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
49
50void synchronize_srcu(struct srcu_struct *ssp);
51
52/*
53 * Counts the new reader in the appropriate per-CPU element of the
54 * srcu_struct. Can be invoked from irq/bh handlers, but the matching
55 * __srcu_read_unlock() must be in the same handler instance. Returns an
56 * index that must be passed to the matching srcu_read_unlock().
57 */
58static inline int __srcu_read_lock(struct srcu_struct *ssp)
59{
60 int idx;
61
62 idx = READ_ONCE(ssp->srcu_idx);
63 WRITE_ONCE(ssp->srcu_lock_nesting[idx], ssp->srcu_lock_nesting[idx] + 1);
64 return idx;
65}
66
67static inline void synchronize_srcu_expedited(struct srcu_struct *ssp)
68{
69 synchronize_srcu(ssp);
70}
71
72static inline void srcu_barrier(struct srcu_struct *ssp)
73{
74 synchronize_srcu(ssp);
75}
76
77/* Defined here to avoid size increase for non-torture kernels. */
78static inline void srcu_torture_stats_print(struct srcu_struct *ssp,
79 char *tt, char *tf)
80{
81 int idx;
82
83 idx = READ_ONCE(ssp->srcu_idx) & 0x1;
84 pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd)\n",
85 tt, tf, idx,
86 READ_ONCE(ssp->srcu_lock_nesting[!idx]),
87 READ_ONCE(ssp->srcu_lock_nesting[idx]));
88}
89
90#endif
91

Warning: That file was not part of the compilation database. It may have many parsing errors.