Line data    Source code

       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             : #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           0 :         return !current->in_eventfd_signal;
      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             :