1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * include/linux/eventfd.h 4 * 5 * Copyright (C) 2007 Davide Libenzi <[email protected]> 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 #include <linux/sched.h> 18 19 /* 20 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining 21 * new flags, since they might collide with O_* ones. We want 22 * to re-use O_* flags that couldn't possibly have a meaning 23 * from eventfd, in order to leave a free define-space for 24 * shared O_* flags. 25 */ 26 #define EFD_SEMAPHORE (1 << 0) 27 #define EFD_CLOEXEC O_CLOEXEC 28 #define EFD_NONBLOCK O_NONBLOCK 29 30 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) 31 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE) 32 33 struct eventfd_ctx; 34 struct file; 35 36 #ifdef CONFIG_EVENTFD 37 38 void eventfd_ctx_put(struct eventfd_ctx *ctx); 39 struct file *eventfd_fget(int fd); 40 struct eventfd_ctx *eventfd_ctx_fdget(int fd); 41 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file); 42 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n); 43 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait, 44 __u64 *cnt); 45 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt); 46 47 static inline bool eventfd_signal_allowed(void) 48 { 49 return !current->in_eventfd; 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_allowed(void) 81 { 82 return true; 83 } 84 85 static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt) 86 { 87 88 } 89 90 #endif 91 92 #endif /* _LINUX_EVENTFD_H */ 93 94