| // SPDX-License-Identifier: GPL-2.0 |
| /* User-mappable watch queue |
| * |
| * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| * |
| * See Documentation/watch_queue.rst |
| */ |
| |
| #ifndef _LINUX_WATCH_QUEUE_H |
| #define _LINUX_WATCH_QUEUE_H |
| |
| #include <uapi/linux/watch_queue.h> |
| #include <linux/kref.h> |
| #include <linux/rcupdate.h> |
| |
| #ifdef CONFIG_WATCH_QUEUE |
| |
| struct cred; |
| |
| struct watch_type_filter { |
| enum watch_notification_type type; |
| __u32 subtype_filter[1]; /* Bitmask of subtypes to filter on */ |
| __u32 info_filter; /* Filter on watch_notification::info */ |
| __u32 info_mask; /* Mask of relevant bits in info_filter */ |
| }; |
| |
| struct watch_filter { |
| union { |
| struct rcu_head rcu; |
| unsigned long type_filter[2]; /* Bitmask of accepted types */ |
| }; |
| u32 nr_filters; /* Number of filters */ |
| struct watch_type_filter filters[]; |
| }; |
| |
| struct watch_queue { |
| struct rcu_head rcu; |
| struct watch_filter __rcu *filter; |
| struct pipe_inode_info *pipe; /* The pipe we're using as a buffer */ |
| struct hlist_head watches; /* Contributory watches */ |
| struct page **notes; /* Preallocated notifications */ |
| unsigned long *notes_bitmap; /* Allocation bitmap for notes */ |
| struct kref usage; /* Object usage count */ |
| spinlock_t lock; |
| unsigned int nr_notes; /* Number of notes */ |
| unsigned int nr_pages; /* Number of pages in notes[] */ |
| bool defunct; /* T when queues closed */ |
| }; |
| |
| /* |
| * Representation of a watch on an object. |
| */ |
| struct watch { |
| union { |
| struct rcu_head rcu; |
| u32 info_id; /* ID to be OR'd in to info field */ |
| }; |
| struct watch_queue __rcu *queue; /* Queue to post events to */ |
| struct hlist_node queue_node; /* Link in queue->watches */ |
| struct watch_list __rcu *watch_list; |
| struct hlist_node list_node; /* Link in watch_list->watchers */ |
| const struct cred *cred; /* Creds of the owner of the watch */ |
| void *private; /* Private data for the watched object */ |
| u64 id; /* Internal identifier */ |
| struct kref usage; /* Object usage count */ |
| }; |
| |
| /* |
| * List of watches on an object. |
| */ |
| struct watch_list { |
| struct rcu_head rcu; |
| struct hlist_head watchers; |
| void (*release_watch)(struct watch *); |
| spinlock_t lock; |
| }; |
| |
| extern void __post_watch_notification(struct watch_list *, |
| struct watch_notification *, |
| const struct cred *, |
| u64); |
| extern struct watch_queue *get_watch_queue(int); |
| extern void put_watch_queue(struct watch_queue *); |
| extern void init_watch(struct watch *, struct watch_queue *); |
| extern int add_watch_to_object(struct watch *, struct watch_list *); |
| extern int remove_watch_from_object(struct watch_list *, struct watch_queue *, u64, bool); |
| extern long watch_queue_set_size(struct pipe_inode_info *, unsigned int); |
| extern long watch_queue_set_filter(struct pipe_inode_info *, |
| struct watch_notification_filter __user *); |
| extern int watch_queue_init(struct pipe_inode_info *); |
| extern void watch_queue_clear(struct watch_queue *); |
| |
| static inline void init_watch_list(struct watch_list *wlist, |
| void (*release_watch)(struct watch *)) |
| { |
| INIT_HLIST_HEAD(&wlist->watchers); |
| spin_lock_init(&wlist->lock); |
| wlist->release_watch = release_watch; |
| } |
| |
| static inline void post_watch_notification(struct watch_list *wlist, |
| struct watch_notification *n, |
| const struct cred *cred, |
| u64 id) |
| { |
| if (unlikely(wlist)) |
| __post_watch_notification(wlist, n, cred, id); |
| } |
| |
| static inline void remove_watch_list(struct watch_list *wlist, u64 id) |
| { |
| if (wlist) { |
| remove_watch_from_object(wlist, NULL, id, true); |
| kfree_rcu(wlist, rcu); |
| } |
| } |
| |
| /** |
| * watch_sizeof - Calculate the information part of the size of a watch record, |
| * given the structure size. |
| */ |
| #define watch_sizeof(STRUCT) (sizeof(STRUCT) << WATCH_INFO_LENGTH__SHIFT) |
| |
| #else |
| static inline int watch_queue_init(struct pipe_inode_info *pipe) |
| { |
| return -ENOPKG; |
| } |
| |
| #endif |
| |
| #endif /* _LINUX_WATCH_QUEUE_H */ |