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eventfd: revised interface and cleanups

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Change the eventfd interface to de-couple the eventfd memory context, from
the file pointer instance.

Without such change, there is no clean way to racely free handle the
POLLHUP event sent when the last instance of the file* goes away.  Also,
now the internal eventfd APIs are using the eventfd context instead of the
file*.

This patch is required by KVM's IRQfd code, which is still under
development.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Gregory Haskins <ghaskins@novell.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Davide Libenzi
2009-06-30 11:41:11 -07:00
committed by Linus Torvalds
parent f7c2df9b55
commit 133890103b
6 changed files with 149 additions and 42 deletions
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35
include/linux/eventfd.h
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@@ -8,10 +8,8 @@
#ifndef _LINUX_EVENTFD_H
#define _LINUX_EVENTFD_H
#ifdef CONFIG_EVENTFD
/* For O_CLOEXEC and O_NONBLOCK */
#include <linux/fcntl.h>
#include <linux/file.h>
/*
* CAREFUL: Check include/asm-generic/fcntl.h when defining
@@ -27,16 +25,37 @@
#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
#ifdef CONFIG_EVENTFD
struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
void eventfd_ctx_put(struct eventfd_ctx *ctx);
struct file *eventfd_fget(int fd);
int eventfd_signal(struct file *file, int n);
struct eventfd_ctx *eventfd_ctx_fdget(int fd);
struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
int eventfd_signal(struct eventfd_ctx *ctx, int n);
#else /* CONFIG_EVENTFD */
#define eventfd_fget(fd) ERR_PTR(-ENOSYS)
static inline int eventfd_signal(struct file *file, int n)
{ return 0; }
/*
* Ugly ugly ugly error layer to support modules that uses eventfd but
* pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
*/
static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
{
return ERR_PTR(-ENOSYS);
}
#endif /* CONFIG_EVENTFD */
static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
{
return -ENOSYS;
}
static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
{
}
#endif
#endif /* _LINUX_EVENTFD_H */