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eventfd: convert to use anon_inode_getfd() 

Nothing actually calls eventfd_file_create() besides the eventfd2()
system call itself.  So simplify things by folding it into the system
call and using anon_inode_getfd() instead of anon_inode_getfile().  This
removes over 40 lines with no change in functionality.

(eventfd_file_create() was apparently added years ago for KVM irqfd's,
but was never used.)

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Eric Biggers 2018-01-06 09:45:42 -08:00 committed by Al Viro
parent 6db620012f
commit 7d815165c1
2 changed files with 7 additions and 51 deletions
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53
fs/eventfd.c
View File

@ -412,72 +412,33 @@ struct eventfd_ctx *eventfd_ctx_fileget(struct file *file)
}
EXPORT_SYMBOL_GPL(eventfd_ctx_fileget);
/**
* eventfd_file_create - Creates an eventfd file pointer.
* @count: Initial eventfd counter value.
* @flags: Flags for the eventfd file.
*
* This function creates an eventfd file pointer, w/out installing it into
* the fd table. This is useful when the eventfd file is used during the
* initialization of data structures that require extra setup after the eventfd
* creation. So the eventfd creation is split into the file pointer creation
* phase, and the file descriptor installation phase.
* In this way races with userspace closing the newly installed file descriptor
* can be avoided.
* Returns an eventfd file pointer, or a proper error pointer.
*/
struct file *eventfd_file_create(unsigned int count, int flags)
SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
{
struct file *file;
struct eventfd_ctx *ctx;
int fd;
/* Check the EFD_* constants for consistency. */
BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC);
BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK);
if (flags & ~EFD_FLAGS_SET)
return ERR_PTR(-EINVAL);
return -EINVAL;
ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return ERR_PTR(-ENOMEM);
return -ENOMEM;
kref_init(&ctx->kref);
init_waitqueue_head(&ctx->wqh);
ctx->count = count;
ctx->flags = flags;
file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx,
O_RDWR | (flags & EFD_SHARED_FCNTL_FLAGS));
if (IS_ERR(file))
fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx,
O_RDWR | (flags & EFD_SHARED_FCNTL_FLAGS));
if (fd < 0)
eventfd_free_ctx(ctx);
return file;
}
SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
{
int fd, error;
struct file *file;
error = get_unused_fd_flags(flags & EFD_SHARED_FCNTL_FLAGS);
if (error < 0)
return error;
fd = error;
file = eventfd_file_create(count, flags);
if (IS_ERR(file)) {
error = PTR_ERR(file);
goto err_put_unused_fd;
}
fd_install(fd, file);
return fd;
err_put_unused_fd:
put_unused_fd(fd);
return error;
}
SYSCALL_DEFINE1(eventfd, unsigned int, count)

5
include/linux/eventfd.h
View File

@ -30,7 +30,6 @@ struct file;
#ifdef CONFIG_EVENTFD
struct file *eventfd_file_create(unsigned int count, int flags);
struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
void eventfd_ctx_put(struct eventfd_ctx *ctx);
struct file *eventfd_fget(int fd);
@ -47,10 +46,6 @@ int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *w
* Ugly ugly ugly error layer to support modules that uses eventfd but
* pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
*/
static inline struct file *eventfd_file_create(unsigned int count, int flags)
{
return ERR_PTR(-ENOSYS);
}
static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
{