linux-kernel - Re: [PATCH v2 1/2] mm/memfd: Refactor and cleanup the logic in memfd

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Message-ID: <CAH5fLgiS+LDUARGet0YO_GohEB=oUasJfKXgu-ghVV_VV-GU1g@mail.gmail.com>
Date: Wed, 8 Jan 2025 14:31:58 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: "Isaac J. Manjarres" <isaacmanjarres@...gle.com>
Cc: lorenzo.stoakes@...cle.com, Andrew Morton <akpm@...ux-foundation.org>, 
	kaleshsingh@...gle.com, jstultz@...gle.com, surenb@...gle.com, 
	kernel-team@...roid.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mm/memfd: Refactor and cleanup the logic in memfd_create()

On Tue, Jan 7, 2025 at 7:48 PM Isaac J. Manjarres
<isaacmanjarres@...gle.com> wrote:
> +SYSCALL_DEFINE2(memfd_create,
> +               const char __user *, uname,
> +               unsigned int, flags)
> +{
> +       struct file *file;
> +       int fd;
> +       char *name;
> +
> +       name = memfd_create_name(uname);
> +       if (IS_ERR(name))
> +               return PTR_ERR(name);
> +
> +       file = memfd_file_create(name, flags);
> +       /* name is not needed beyond this point. */
>         kfree(name);
> -       return error;
> +       if (IS_ERR(file))
> +               return PTR_ERR(file);
> +
> +       fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
> +       if (fd >= 0)
> +               fd_install(fd, file);
> +       else
> +               fput(file);

You changed the order so that get_unused_fd_flags() happens after
creating the file, so the error path now does fput(file) instead of
put_unused_fd(fd). Is there a reason for this? I would generally
assume that calling get_unused_fd_flags() first is better.

Otherwise this LGTM.


Alice