diff options
| -rw-r--r-- | fs/anon_inodes.c | 68 | ||||
| -rw-r--r-- | fs/eventfd.c | 67 | ||||
| -rw-r--r-- | include/linux/anon_inodes.h | 3 | ||||
| -rw-r--r-- | include/linux/eventfd.h | 6 |
4 files changed, 114 insertions, 30 deletions
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index 47d4a01c539..d11c51fc2a3 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -77,28 +77,24 @@ static const struct address_space_operations anon_aops = { * * Creates a new file by hooking it on a single inode. This is useful for files * that do not need to have a full-fledged inode in order to operate correctly. - * All the files created with anon_inode_getfd() will share a single inode, + * All the files created with anon_inode_getfile() will share a single inode, * hence saving memory and avoiding code duplication for the file/inode/dentry - * setup. Returns new descriptor or -error. + * setup. Returns the newly created file* or an error pointer. */ -int anon_inode_getfd(const char *name, const struct file_operations *fops, - void *priv, int flags) +struct file *anon_inode_getfile(const char *name, + const struct file_operations *fops, + void *priv, int flags) { struct qstr this; struct dentry *dentry; struct file *file; - int error, fd; + int error; if (IS_ERR(anon_inode_inode)) - return -ENODEV; + return ERR_PTR(-ENODEV); if (fops->owner && !try_module_get(fops->owner)) - return -ENOENT; - - error = get_unused_fd_flags(flags); - if (error < 0) - goto err_module; - fd = error; + return ERR_PTR(-ENOENT); /* * Link the inode to a directory entry by creating a unique name @@ -110,7 +106,7 @@ int anon_inode_getfd(const char *name, const struct file_operations *fops, this.hash = 0; dentry = d_alloc(anon_inode_mnt->mnt_sb->s_root, &this); if (!dentry) - goto err_put_unused_fd; + goto err_module; /* * We know the anon_inode inode count is always greater than zero, @@ -136,16 +132,54 @@ int anon_inode_getfd(const char *name, const struct file_operations *fops, file->f_version = 0; file->private_data = priv; + return file; + +err_dput: + dput(dentry); +err_module: + module_put(fops->owner); + return ERR_PTR(error); +} +EXPORT_SYMBOL_GPL(anon_inode_getfile); + +/** + * anon_inode_getfd - creates a new file instance by hooking it up to an + * anonymous inode, and a dentry that describe the "class" + * of the file + * + * @name: [in] name of the "class" of the new file + * @fops: [in] file operations for the new file + * @priv: [in] private data for the new file (will be file's private_data) + * @flags: [in] flags + * + * Creates a new file by hooking it on a single inode. This is useful for files + * that do not need to have a full-fledged inode in order to operate correctly. + * All the files created with anon_inode_getfd() will share a single inode, + * hence saving memory and avoiding code duplication for the file/inode/dentry + * setup. Returns new descriptor or an error code. + */ +int anon_inode_getfd(const char *name, const struct file_operations *fops, + void *priv, int flags) +{ + int error, fd; + struct file *file; + + error = get_unused_fd_flags(flags); + if (error < 0) + return error; + fd = error; + + file = anon_inode_getfile(name, fops, priv, flags); + if (IS_ERR(file)) { + error = PTR_ERR(file); + goto err_put_unused_fd; + } fd_install(fd, file); return fd; -err_dput: - dput(dentry); err_put_unused_fd: put_unused_fd(fd); -err_module: - module_put(fops->owner); return error; } EXPORT_SYMBOL_GPL(anon_inode_getfd); diff --git a/fs/eventfd.c b/fs/eventfd.c index 31d12de83a2..8b47e4200e6 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -68,11 +68,16 @@ int eventfd_signal(struct eventfd_ctx *ctx, int n) } EXPORT_SYMBOL_GPL(eventfd_signal); +static void eventfd_free_ctx(struct eventfd_ctx *ctx) +{ + kfree(ctx); +} + static void eventfd_free(struct kref *kref) { struct eventfd_ctx *ctx = container_of(kref, struct eventfd_ctx, kref); - kfree(ctx); + eventfd_free_ctx(ctx); } /** @@ -298,9 +303,23 @@ struct eventfd_ctx *eventfd_ctx_fileget(struct file *file) } EXPORT_SYMBOL_GPL(eventfd_ctx_fileget); -SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags) +/** + * 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) { - int fd; + struct file *file; struct eventfd_ctx *ctx; /* Check the EFD_* constants for consistency. */ @@ -308,26 +327,48 @@ SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags) BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK); if (flags & ~EFD_FLAGS_SET) - return -EINVAL; + return ERR_PTR(-EINVAL); ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) - return -ENOMEM; + return ERR_PTR(-ENOMEM); kref_init(&ctx->kref); init_waitqueue_head(&ctx->wqh); ctx->count = count; ctx->flags = flags; - /* - * When we call this, the initialization must be complete, since - * anon_inode_getfd() will install the fd. - */ - fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx, - flags & EFD_SHARED_FCNTL_FLAGS); - if (fd < 0) - kfree(ctx); + file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx, + flags & EFD_SHARED_FCNTL_FLAGS); + if (IS_ERR(file)) + 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) diff --git a/include/linux/anon_inodes.h b/include/linux/anon_inodes.h index e0a0cdc2da4..69a21e0ebd3 100644 --- a/include/linux/anon_inodes.h +++ b/include/linux/anon_inodes.h @@ -8,6 +8,9 @@ #ifndef _LINUX_ANON_INODES_H #define _LINUX_ANON_INODES_H +struct file *anon_inode_getfile(const char *name, + const struct file_operations *fops, + void *priv, int flags); int anon_inode_getfd(const char *name, const struct file_operations *fops, void *priv, int flags); diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h index 3b85ba6479f..94dd10366a7 100644 --- a/include/linux/eventfd.h +++ b/include/linux/eventfd.h @@ -27,6 +27,7 @@ #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); @@ -40,6 +41,11 @@ int eventfd_signal(struct eventfd_ctx *ctx, int n); * 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) { return ERR_PTR(-ENOSYS); |