1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * include/linux/eventfd.h 4 * 5 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org> 6 * 7 */ 8 9#ifndef _LINUX_EVENTFD_H 10#define _LINUX_EVENTFD_H 11 12#include <linux/fcntl.h> 13#include <linux/wait.h> 14#include <linux/err.h> 15#include <linux/percpu-defs.h> 16#include <linux/percpu.h> 17 18/* 19 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining 20 * new flags, since they might collide with O_* ones. We want 21 * to re-use O_* flags that couldn't possibly have a meaning 22 * from eventfd, in order to leave a free define-space for 23 * shared O_* flags. 24 */ 25#define EFD_SEMAPHORE (1 << 0) 26#define EFD_CLOEXEC O_CLOEXEC 27#define EFD_NONBLOCK O_NONBLOCK 28 29#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) 30#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE) 31 32struct eventfd_ctx; 33struct file; 34 35#ifdef CONFIG_EVENTFD 36 37void eventfd_ctx_put(struct eventfd_ctx *ctx); 38struct file *eventfd_fget(int fd); 39struct eventfd_ctx *eventfd_ctx_fdget(int fd); 40struct eventfd_ctx *eventfd_ctx_fileget(struct file *file); 41__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n); 42int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait, 43 __u64 *cnt); 44 45DECLARE_PER_CPU(int, eventfd_wake_count); 46 47static inline bool eventfd_signal_count(void) 48{ 49 return this_cpu_read(eventfd_wake_count); 50} 51 52#else /* CONFIG_EVENTFD */ 53 54/* 55 * Ugly ugly ugly error layer to support modules that uses eventfd but 56 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO. 57 */ 58 59static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd) 60{ 61 return ERR_PTR(-ENOSYS); 62} 63 64static inline int eventfd_signal(struct eventfd_ctx *ctx, int n) 65{ 66 return -ENOSYS; 67} 68 69static inline void eventfd_ctx_put(struct eventfd_ctx *ctx) 70{ 71 72} 73 74static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, 75 wait_queue_entry_t *wait, __u64 *cnt) 76{ 77 return -ENOSYS; 78} 79 80static inline bool eventfd_signal_count(void) 81{ 82 return false; 83} 84 85#endif 86 87#endif /* _LINUX_EVENTFD_H */ 88 89