linux-kernel - Re: [PATCH] fuse: don't set file->private_data in fuse_conn_waiting

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Message-ID: <CAJfpegsOOv7c3R5zQZWWvYEgZxyWGCJyf8z=A8swQQZsGyvuDQ@mail.gmail.com>
Date: Fri, 14 Feb 2025 11:17:36 +0100
From: Miklos Szeredi <miklos@...redi.hu>
To: Jeff Layton <jlayton@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fuse: don't set file->private_data in fuse_conn_waiting_read

On Tue, 4 Feb 2025 at 16:04, Jeff Layton <jlayton@...nel.org> wrote:
>
> I see no reason to set the private_data on the file to this value. Just
> grab the result of the atomic_read() and output it without setting
> private_data.
>
> Signed-off-by: Jeff Layton <jlayton@...nel.org>
> ---
>  fs/fuse/control.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/fs/fuse/control.c b/fs/fuse/control.c
> index 2a730d88cc3bdb50ea1f8a3185faad5f05fc6e74..17ef07cf0c38e44bd7eadb3450bd53a8acc5e885 100644
> --- a/fs/fuse/control.c
> +++ b/fs/fuse/control.c
> @@ -49,18 +49,17 @@ static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
>  {
>         char tmp[32];
>         size_t size;
> +       int value;
>
>         if (!*ppos) {
> -               long value;
>                 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
>                 if (!fc)
>                         return 0;
>
>                 value = atomic_read(&fc->num_waiting);
> -               file->private_data = (void *)value;
>                 fuse_conn_put(fc);
>         }

"value" is uninitialized if *ppos is non-zero.

I also wonder why this patch is an improvement (with the bug fixed)?

Thanks,
Mikos