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 | * |
7 | * See Documentation/core-api/watch_queue.rst |
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; |
31 | /* Bitmask of accepted types */ |
32 | DECLARE_BITMAP(type_filter, WATCH_TYPE__NR); |
33 | }; |
34 | u32 nr_filters; /* Number of filters */ |
35 | struct watch_type_filter filters[] __counted_by(nr_filters); |
36 | }; |
37 | |
38 | struct watch_queue { |
39 | struct rcu_head rcu; |
40 | struct watch_filter __rcu *filter; |
41 | struct pipe_inode_info *pipe; /* Pipe we use as a buffer, NULL if queue closed */ |
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[] */ |
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 | |
125 | #else |
126 | static inline int watch_queue_init(struct pipe_inode_info *pipe) |
127 | { |
128 | return -ENOPKG; |
129 | } |
130 | |
131 | #endif |
132 | |
133 | #endif /* _LINUX_WATCH_QUEUE_H */ |
134 | |