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 32 struct eventfd_ctx; 33 struct file; 34 35 #ifdef CONFIG_EVENTFD 36 37 void eventfd_ctx_put(struct eventfd_ctx *ctx); 38 struct file *eventfd_fget(int fd); 39 struct eventfd_ctx *eventfd_ctx_fdget(int fd); 40 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file); 41 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n); 42 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait, 43 __u64 *cnt); 44 45 DECLARE_PER_CPU(int, eventfd_wake_count); 46 47 static 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 59 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd) 60 { 61 return ERR_PTR(-ENOSYS); 62 } 63 64 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n) 65 { 66 return -ENOSYS; 67 } 68 69 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx) 70 { 71 72 } 73 74 static 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 80 static inline bool eventfd_signal_count(void) 81 { 82 return false; 83 } 84 85 #endif 86 87 #endif /* _LINUX_EVENTFD_H */ 88 89