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 15 /* 16 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining 17 * new flags, since they might collide with O_* ones. We want 18 * to re-use O_* flags that couldn't possibly have a meaning 19 * from eventfd, in order to leave a free define-space for 20 * shared O_* flags. 21 */ 22 #define EFD_SEMAPHORE (1 << 0) 23 #define EFD_CLOEXEC O_CLOEXEC 24 #define EFD_NONBLOCK O_NONBLOCK 25 26 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) 27 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE) 28 29 struct file; 30 31 #ifdef CONFIG_EVENTFD 32 33 struct file *eventfd_file_create(unsigned int count, int flags); 34 struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx); 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 ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt); 41 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait, 42 __u64 *cnt); 43 44 #else /* CONFIG_EVENTFD */ 45 46 /* 47 * Ugly ugly ugly error layer to support modules that uses eventfd but 48 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO. 49 */ 50 static inline struct file *eventfd_file_create(unsigned int count, int flags) 51 { 52 return ERR_PTR(-ENOSYS); 53 } 54 55 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd) 56 { 57 return ERR_PTR(-ENOSYS); 58 } 59 60 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n) 61 { 62 return -ENOSYS; 63 } 64 65 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx) 66 { 67 68 } 69 70 static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, 71 __u64 *cnt) 72 { 73 return -ENOSYS; 74 } 75 76 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, 77 wait_queue_entry_t *wait, __u64 *cnt) 78 { 79 return -ENOSYS; 80 } 81 82 #endif 83 84 #endif /* _LINUX_EVENTFD_H */ 85 86