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 16 /* 17 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining 18 * new flags, since they might collide with O_* ones. We want 19 * to re-use O_* flags that couldn't possibly have a meaning 20 * from eventfd, in order to leave a free define-space for 21 * shared O_* flags. 22 */ 23 #define EFD_SEMAPHORE (1 << 0) 24 #define EFD_CLOEXEC O_CLOEXEC 25 #define EFD_NONBLOCK O_NONBLOCK 26 27 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) 28 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE) 29 30 struct eventfd_ctx; 31 struct file; 32 33 #ifdef CONFIG_EVENTFD 34 35 void eventfd_ctx_put(struct eventfd_ctx *ctx); 36 struct file *eventfd_fget(int fd); 37 struct eventfd_ctx *eventfd_ctx_fdget(int fd); 38 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file); 39 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n); 40 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait, 41 __u64 *cnt); 42 43 #else /* CONFIG_EVENTFD */ 44 45 /* 46 * Ugly ugly ugly error layer to support modules that uses eventfd but 47 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO. 48 */ 49 50 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd) 51 { 52 return ERR_PTR(-ENOSYS); 53 } 54 55 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n) 56 { 57 return -ENOSYS; 58 } 59 60 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx) 61 { 62 63 } 64 65 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, 66 wait_queue_entry_t *wait, __u64 *cnt) 67 { 68 return -ENOSYS; 69 } 70 71 #endif 72 73 #endif /* _LINUX_EVENTFD_H */ 74 75