cb289d6244
KVM needs a wait to atomically remove themselves from the eventfd ->poll() wait queue head, in order to handle correctly their IRQfd deassign operation. This patch introduces such API, plus a way to read an eventfd from its context. Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Avi Kivity <avi@redhat.com>
83 lines
2.1 KiB
C
83 lines
2.1 KiB
C
/*
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* include/linux/eventfd.h
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*
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* Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
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*
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*/
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#ifndef _LINUX_EVENTFD_H
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#define _LINUX_EVENTFD_H
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#include <linux/fcntl.h>
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#include <linux/file.h>
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#include <linux/wait.h>
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/*
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* CAREFUL: Check include/asm-generic/fcntl.h when defining
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* new flags, since they might collide with O_* ones. We want
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* to re-use O_* flags that couldn't possibly have a meaning
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* from eventfd, in order to leave a free define-space for
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* shared O_* flags.
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*/
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#define EFD_SEMAPHORE (1 << 0)
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#define EFD_CLOEXEC O_CLOEXEC
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#define EFD_NONBLOCK O_NONBLOCK
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#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
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#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
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#ifdef CONFIG_EVENTFD
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struct file *eventfd_file_create(unsigned int count, int flags);
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struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
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void eventfd_ctx_put(struct eventfd_ctx *ctx);
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struct file *eventfd_fget(int fd);
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struct eventfd_ctx *eventfd_ctx_fdget(int fd);
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struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
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int eventfd_signal(struct eventfd_ctx *ctx, int n);
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ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
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int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_t *wait,
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__u64 *cnt);
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#else /* CONFIG_EVENTFD */
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/*
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* Ugly ugly ugly error layer to support modules that uses eventfd but
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* pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
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*/
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static inline struct file *eventfd_file_create(unsigned int count, int flags)
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{
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return ERR_PTR(-ENOSYS);
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}
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static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
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{
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return ERR_PTR(-ENOSYS);
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}
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static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
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{
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return -ENOSYS;
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}
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static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
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{
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}
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static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
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__u64 *cnt)
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{
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return -ENOSYS;
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}
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static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
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wait_queue_t *wait, __u64 *cnt)
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{
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return -ENOSYS;
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}
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#endif
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#endif /* _LINUX_EVENTFD_H */
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