]>
Commit | Line | Data |
---|---|---|
15fecf89 PM |
1 | /* |
2 | * RCU segmented callback lists | |
3 | * | |
aaaad0bf PM |
4 | * This seemingly RCU-private file must be available to SRCU users |
5 | * because the size of the TREE SRCU srcu_struct structure depends | |
6 | * on these definitions. | |
7 | * | |
15fecf89 PM |
8 | * This program is free software; you can redistribute it and/or modify |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, you can access it online at | |
20 | * http://www.gnu.org/licenses/gpl-2.0.html. | |
21 | * | |
22 | * Copyright IBM Corporation, 2017 | |
23 | * | |
24 | * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
25 | */ | |
26 | ||
45753c5f IM |
27 | #ifndef __INCLUDE_LINUX_RCU_SEGCBLIST_H |
28 | #define __INCLUDE_LINUX_RCU_SEGCBLIST_H | |
15fecf89 PM |
29 | |
30 | /* Simple unsegmented callback lists. */ | |
31 | struct rcu_cblist { | |
32 | struct rcu_head *head; | |
33 | struct rcu_head **tail; | |
34 | long len; | |
35 | long len_lazy; | |
36 | }; | |
37 | ||
38 | #define RCU_CBLIST_INITIALIZER(n) { .head = NULL, .tail = &n.head } | |
39 | ||
15fecf89 PM |
40 | /* Complicated segmented callback lists. ;-) */ |
41 | ||
42 | /* | |
43 | * Index values for segments in rcu_segcblist structure. | |
44 | * | |
45 | * The segments are as follows: | |
46 | * | |
47 | * [head, *tails[RCU_DONE_TAIL]): | |
48 | * Callbacks whose grace period has elapsed, and thus can be invoked. | |
49 | * [*tails[RCU_DONE_TAIL], *tails[RCU_WAIT_TAIL]): | |
50 | * Callbacks waiting for the current GP from the current CPU's viewpoint. | |
51 | * [*tails[RCU_WAIT_TAIL], *tails[RCU_NEXT_READY_TAIL]): | |
52 | * Callbacks that arrived before the next GP started, again from | |
53 | * the current CPU's viewpoint. These can be handled by the next GP. | |
54 | * [*tails[RCU_NEXT_READY_TAIL], *tails[RCU_NEXT_TAIL]): | |
55 | * Callbacks that might have arrived after the next GP started. | |
56 | * There is some uncertainty as to when a given GP starts and | |
57 | * ends, but a CPU knows the exact times if it is the one starting | |
58 | * or ending the GP. Other CPUs know that the previous GP ends | |
59 | * before the next one starts. | |
60 | * | |
61 | * Note that RCU_WAIT_TAIL cannot be empty unless RCU_NEXT_READY_TAIL is also | |
62 | * empty. | |
63 | * | |
64 | * The ->gp_seq[] array contains the grace-period number at which the | |
65 | * corresponding segment of callbacks will be ready to invoke. A given | |
66 | * element of this array is meaningful only when the corresponding segment | |
67 | * is non-empty, and it is never valid for RCU_DONE_TAIL (whose callbacks | |
68 | * are already ready to invoke) or for RCU_NEXT_TAIL (whose callbacks have | |
69 | * not yet been assigned a grace-period number). | |
70 | */ | |
71 | #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ | |
72 | #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ | |
73 | #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ | |
74 | #define RCU_NEXT_TAIL 3 | |
75 | #define RCU_CBLIST_NSEGS 4 | |
76 | ||
77 | struct rcu_segcblist { | |
78 | struct rcu_head *head; | |
79 | struct rcu_head **tails[RCU_CBLIST_NSEGS]; | |
80 | unsigned long gp_seq[RCU_CBLIST_NSEGS]; | |
81 | long len; | |
82 | long len_lazy; | |
83 | }; | |
84 | ||
8660b7d8 PM |
85 | #define RCU_SEGCBLIST_INITIALIZER(n) \ |
86 | { \ | |
87 | .head = NULL, \ | |
88 | .tails[RCU_DONE_TAIL] = &n.head, \ | |
89 | .tails[RCU_WAIT_TAIL] = &n.head, \ | |
90 | .tails[RCU_NEXT_READY_TAIL] = &n.head, \ | |
91 | .tails[RCU_NEXT_TAIL] = &n.head, \ | |
92 | } | |
93 | ||
45753c5f | 94 | #endif /* __INCLUDE_LINUX_RCU_SEGCBLIST_H */ |