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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* include/linux/eventpoll.h ( Efficient event polling implementation )
* Copyright (C) 2001,...,2006 Davide Libenzi
*
* Davide Libenzi <davidel@xmailserver.org>
*/
#ifndef _LINUX_EVENTPOLL_H
#define _LINUX_EVENTPOLL_H
#include <uapi/linux/eventpoll.h>
#include <uapi/linux/kcmp.h>
/* Forward declarations to avoid compiler errors */
struct file;
#ifdef CONFIG_EPOLL
#ifdef CONFIG_KCMP
struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff);
#endif
/* Used to release the epoll bits inside the "struct file" */
void eventpoll_release_file(struct file *file);
/* Copy ready events to userspace */
int epoll_sendevents(struct file *file, struct epoll_event __user *events,
int maxevents);
/*
* This is called from inside fs/file_table.c:__fput() to unlink files
* from the eventpoll interface. We need to have this facility to cleanup
* correctly files that are closed without being removed from the eventpoll
* interface.
*/
static inline void eventpoll_release(struct file *file)
{
/*
* Fast check to skip the slow path in the common case where the
* file was never attached to an epoll. Safe without file->f_lock
* because every f_ep writer excludes a concurrent __fput() on
* @file:
* - ep_insert() requires the file alive (refcount > 0);
* - ep_remove() holds @file pinned via epi_fget() across the
* write;
* - eventpoll_release_file() runs from __fput() itself.
* We are in __fput() here, so none of those can race us: a NULL
* observation truly means no epoll path has work left on @file.
*/
if (likely(!READ_ONCE(file->f_ep)))
return;
/*
* The file is being closed while it is still linked to an epoll
* descriptor. We need to handle this by correctly unlinking it
* from its containers.
*/
eventpoll_release_file(file);
}
int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
bool nonblock);
/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
static inline int ep_op_has_event(int op)
{
return op != EPOLL_CTL_DEL;
}
#else
static inline void eventpoll_release(struct file *file) {}
#endif
#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT)
/* ARM OABI has an incompatible struct layout and needs a special handler */
extern struct epoll_event __user *
epoll_put_uevent(__poll_t revents, __u64 data,
struct epoll_event __user *uevent);
#else
static inline struct epoll_event __user *
epoll_put_uevent(__poll_t revents, __u64 data,
struct epoll_event __user *uevent)
{
scoped_user_write_access_size(uevent, sizeof(*uevent), efault) {
unsafe_put_user(revents, &uevent->events, efault);
unsafe_put_user(data, &uevent->data, efault);
}
return uevent+1;
efault:
return NULL;
}
#endif
#endif /* #ifndef _LINUX_EVENTPOLL_H */
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