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

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Message-ID: <2ec361038d22e9ed5dbe8e69b08a0a31685c7274.camel@kernel.org>
Date: Fri, 14 Feb 2025 07:58:16 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Miklos Szeredi <miklos@...redi.hu>
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 Fri, 2025-02-14 at 11:17 +0100, Miklos Szeredi wrote:
> 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.
> 

Good catch. Thanks. Do you want me to resend?

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

It's just an unnecessary assignment. Nothing will look at or use
private_data in this codepath, so there is no need to set it.
-- 
Jeff Layton <jlayton@...nel.org>