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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* User-mappable watch queue | |
3 | * | |
4 | * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
6 | * | |
c02b872a | 7 | * See Documentation/core-api/watch_queue.rst |
c73be61c DH |
8 | */ |
9 | ||
10 | #ifndef _LINUX_WATCH_QUEUE_H | |
11 | #define _LINUX_WATCH_QUEUE_H | |
12 | ||
13 | #include <uapi/linux/watch_queue.h> | |
14 | #include <linux/kref.h> | |
15 | #include <linux/rcupdate.h> | |
16 | ||
17 | #ifdef CONFIG_WATCH_QUEUE | |
18 | ||
19 | struct cred; | |
20 | ||
21 | struct watch_type_filter { | |
22 | enum watch_notification_type type; | |
23 | __u32 subtype_filter[1]; /* Bitmask of subtypes to filter on */ | |
24 | __u32 info_filter; /* Filter on watch_notification::info */ | |
25 | __u32 info_mask; /* Mask of relevant bits in info_filter */ | |
26 | }; | |
27 | ||
28 | struct watch_filter { | |
29 | union { | |
30 | struct rcu_head rcu; | |
c993ee0f DH |
31 | /* Bitmask of accepted types */ |
32 | DECLARE_BITMAP(type_filter, WATCH_TYPE__NR); | |
c73be61c DH |
33 | }; |
34 | u32 nr_filters; /* Number of filters */ | |
85fadf89 | 35 | struct watch_type_filter filters[] __counted_by(nr_filters); |
c73be61c DH |
36 | }; |
37 | ||
38 | struct watch_queue { | |
39 | struct rcu_head rcu; | |
40 | struct watch_filter __rcu *filter; | |
943211c8 | 41 | struct pipe_inode_info *pipe; /* Pipe we use as a buffer, NULL if queue closed */ |
c73be61c DH |
42 | struct hlist_head watches; /* Contributory watches */ |
43 | struct page **notes; /* Preallocated notifications */ | |
44 | unsigned long *notes_bitmap; /* Allocation bitmap for notes */ | |
45 | struct kref usage; /* Object usage count */ | |
46 | spinlock_t lock; | |
47 | unsigned int nr_notes; /* Number of notes */ | |
48 | unsigned int nr_pages; /* Number of pages in notes[] */ | |
c73be61c DH |
49 | }; |
50 | ||
51 | /* | |
52 | * Representation of a watch on an object. | |
53 | */ | |
54 | struct watch { | |
55 | union { | |
56 | struct rcu_head rcu; | |
57 | u32 info_id; /* ID to be OR'd in to info field */ | |
58 | }; | |
59 | struct watch_queue __rcu *queue; /* Queue to post events to */ | |
60 | struct hlist_node queue_node; /* Link in queue->watches */ | |
61 | struct watch_list __rcu *watch_list; | |
62 | struct hlist_node list_node; /* Link in watch_list->watchers */ | |
63 | const struct cred *cred; /* Creds of the owner of the watch */ | |
64 | void *private; /* Private data for the watched object */ | |
65 | u64 id; /* Internal identifier */ | |
66 | struct kref usage; /* Object usage count */ | |
67 | }; | |
68 | ||
69 | /* | |
70 | * List of watches on an object. | |
71 | */ | |
72 | struct watch_list { | |
73 | struct rcu_head rcu; | |
74 | struct hlist_head watchers; | |
75 | void (*release_watch)(struct watch *); | |
76 | spinlock_t lock; | |
77 | }; | |
78 | ||
79 | extern void __post_watch_notification(struct watch_list *, | |
80 | struct watch_notification *, | |
81 | const struct cred *, | |
82 | u64); | |
83 | extern struct watch_queue *get_watch_queue(int); | |
84 | extern void put_watch_queue(struct watch_queue *); | |
85 | extern void init_watch(struct watch *, struct watch_queue *); | |
86 | extern int add_watch_to_object(struct watch *, struct watch_list *); | |
87 | extern int remove_watch_from_object(struct watch_list *, struct watch_queue *, u64, bool); | |
88 | extern long watch_queue_set_size(struct pipe_inode_info *, unsigned int); | |
89 | extern long watch_queue_set_filter(struct pipe_inode_info *, | |
90 | struct watch_notification_filter __user *); | |
91 | extern int watch_queue_init(struct pipe_inode_info *); | |
92 | extern void watch_queue_clear(struct watch_queue *); | |
93 | ||
94 | static inline void init_watch_list(struct watch_list *wlist, | |
95 | void (*release_watch)(struct watch *)) | |
96 | { | |
97 | INIT_HLIST_HEAD(&wlist->watchers); | |
98 | spin_lock_init(&wlist->lock); | |
99 | wlist->release_watch = release_watch; | |
100 | } | |
101 | ||
102 | static inline void post_watch_notification(struct watch_list *wlist, | |
103 | struct watch_notification *n, | |
104 | const struct cred *cred, | |
105 | u64 id) | |
106 | { | |
107 | if (unlikely(wlist)) | |
108 | __post_watch_notification(wlist, n, cred, id); | |
109 | } | |
110 | ||
111 | static inline void remove_watch_list(struct watch_list *wlist, u64 id) | |
112 | { | |
113 | if (wlist) { | |
114 | remove_watch_from_object(wlist, NULL, id, true); | |
115 | kfree_rcu(wlist, rcu); | |
116 | } | |
117 | } | |
118 | ||
119 | /** | |
120 | * watch_sizeof - Calculate the information part of the size of a watch record, | |
121 | * given the structure size. | |
122 | */ | |
123 | #define watch_sizeof(STRUCT) (sizeof(STRUCT) << WATCH_INFO_LENGTH__SHIFT) | |
124 | ||
8a018eb5 QC |
125 | #else |
126 | static inline int watch_queue_init(struct pipe_inode_info *pipe) | |
127 | { | |
128 | return -ENOPKG; | |
129 | } | |
130 | ||
c73be61c DH |
131 | #endif |
132 | ||
133 | #endif /* _LINUX_WATCH_QUEUE_H */ |