| David Howells | c73be61 | 2020-01-14 17:07:11 +0000 | [diff] [blame] | 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/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 | unsigned long type_filter[2]; /* Bitmask of accepted types */ |
| 32 | }; |
| 33 | u32 nr_filters; /* Number of filters */ |
| 34 | struct watch_type_filter filters[]; |
| 35 | }; |
| 36 | |
| 37 | struct watch_queue { |
| 38 | struct rcu_head rcu; |
| 39 | struct watch_filter __rcu *filter; |
| 40 | struct pipe_inode_info *pipe; /* The pipe we're using as a buffer */ |
| 41 | struct hlist_head watches; /* Contributory watches */ |
| 42 | struct page **notes; /* Preallocated notifications */ |
| 43 | unsigned long *notes_bitmap; /* Allocation bitmap for notes */ |
| 44 | struct kref usage; /* Object usage count */ |
| 45 | spinlock_t lock; |
| 46 | unsigned int nr_notes; /* Number of notes */ |
| 47 | unsigned int nr_pages; /* Number of pages in notes[] */ |
| 48 | bool defunct; /* T when queues closed */ |
| 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 | #endif |
| 126 | |
| 127 | #endif /* _LINUX_WATCH_QUEUE_H */ |