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1 /* SPDX-License-Identifier: GPL-2.0+ */
3 * Sleepable Read-Copy Update mechanism for mutual exclusion,
6 * Copyright (C) IBM Corporation, 2017
8 * Author: Paul McKenney <paulmck@linux.ibm.com>
11 #ifndef _LINUX_SRCU_TINY_H
12 #define _LINUX_SRCU_TINY_H
14 #include <linux/swait.h>
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 */
31 void srcu_drive_gp(struct work_struct
*wp
);
33 #define __SRCU_STRUCT_INIT(name, __ignored) \
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) \
42 * This odd _STATIC_ arrangement is needed for API compatibility with
43 * Tree SRCU, which needs some per-CPU data.
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)
50 void synchronize_srcu(struct srcu_struct
*ssp
);
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().
58 static inline int __srcu_read_lock(struct srcu_struct
*ssp
)
62 idx
= READ_ONCE(ssp
->srcu_idx
);
63 WRITE_ONCE(ssp
->srcu_lock_nesting
[idx
], ssp
->srcu_lock_nesting
[idx
] + 1);
67 static inline void synchronize_srcu_expedited(struct srcu_struct
*ssp
)
69 synchronize_srcu(ssp
);
72 static inline void srcu_barrier(struct srcu_struct
*ssp
)
74 synchronize_srcu(ssp
);
77 /* Defined here to avoid size increase for non-torture kernels. */
78 static inline void srcu_torture_stats_print(struct srcu_struct
*ssp
,
83 idx
= READ_ONCE(ssp
->srcu_idx
) & 0x1;
84 pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd)\n",
86 READ_ONCE(ssp
->srcu_lock_nesting
[!idx
]),
87 READ_ONCE(ssp
->srcu_lock_nesting
[idx
]));