| 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
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| 2 | /* |
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| 3 | * include/linux/eventpoll.h ( Efficient event polling implementation ) |
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| 4 | * Copyright (C) 2001,...,2006 Davide Libenzi |
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| 5 | * |
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| 6 | * Davide Libenzi <davidel@xmailserver.org> |
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| 7 | */ |
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| 8 | #ifndef _LINUX_EVENTPOLL_H |
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| 9 | #define _LINUX_EVENTPOLL_H |
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| 10 | |
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| 11 | #include <uapi/linux/eventpoll.h> |
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| 12 | #include <uapi/linux/kcmp.h> |
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| 13 | |
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| 14 | |
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| 15 | /* Forward declarations to avoid compiler errors */ |
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| 16 | struct file; |
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| 17 | |
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| 18 | |
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| 19 | #ifdef CONFIG_EPOLL |
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| 20 | |
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| 21 | #ifdef CONFIG_KCMP |
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| 22 | struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff); |
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| 23 | #endif |
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| 24 | |
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| 25 | /* Used to release the epoll bits inside the "struct file" */ |
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| 26 | void eventpoll_release_file(struct file *file); |
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| 27 | |
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| 28 | /* Copy ready events to userspace */ |
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| 29 | int epoll_sendevents(struct file *file, struct epoll_event __user *events, |
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| 30 | int maxevents); |
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| 31 | |
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| 32 | /* |
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| 33 | * This is called from inside fs/file_table.c:__fput() to unlink files |
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| 34 | * from the eventpoll interface. We need to have this facility to cleanup |
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| 35 | * correctly files that are closed without being removed from the eventpoll |
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| 36 | * interface. |
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| 37 | */ |
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| 38 | static inline void eventpoll_release(struct file *file) |
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| 39 | { |
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| 40 | |
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| 41 | /* |
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| 42 | * Fast check to avoid the get/release of the semaphore. Since |
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| 43 | * we're doing this outside the semaphore lock, it might return |
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| 44 | * false negatives, but we don't care. It'll help in 99.99% of cases |
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| 45 | * to avoid the semaphore lock. False positives simply cannot happen |
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| 46 | * because the file in on the way to be removed and nobody ( but |
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| 47 | * eventpoll ) has still a reference to this file. |
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| 48 | */ |
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| 49 | if (likely(!READ_ONCE(file->f_ep))) |
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| 50 | return; |
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| 51 | |
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| 52 | /* |
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| 53 | * The file is being closed while it is still linked to an epoll |
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| 54 | * descriptor. We need to handle this by correctly unlinking it |
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| 55 | * from its containers. |
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| 56 | */ |
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| 57 | eventpoll_release_file(file); |
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| 58 | } |
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| 59 | |
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| 60 | int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds, |
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| 61 | bool nonblock); |
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| 62 | |
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| 63 | /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ |
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| 64 | static inline int ep_op_has_event(int op) |
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| 65 | { |
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| 66 | return op != EPOLL_CTL_DEL; |
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| 67 | } |
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| 68 | |
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| 69 | #else |
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| 70 | |
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| 71 | static inline void eventpoll_release(struct file *file) {} |
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| 72 | |
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| 73 | #endif |
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| 74 | |
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| 75 | #if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT) |
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| 76 | /* ARM OABI has an incompatible struct layout and needs a special handler */ |
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| 77 | extern struct epoll_event __user * |
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| 78 | epoll_put_uevent(__poll_t revents, __u64 data, |
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| 79 | struct epoll_event __user *uevent); |
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| 80 | #else |
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| 81 | static inline struct epoll_event __user * |
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| 82 | epoll_put_uevent(__poll_t revents, __u64 data, |
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| 83 | struct epoll_event __user *uevent) |
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| 84 | { |
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| 85 | if (__put_user(revents, &uevent->events) || |
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| 86 | __put_user(data, &uevent->data)) |
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| 87 | return NULL; |
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| 88 | |
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| 89 | return uevent+1; |
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| 90 | } |
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| 91 | #endif |
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| 92 | |
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| 93 | #endif /* #ifndef _LINUX_EVENTPOLL_H */ |
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| 94 | |
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