Re: [PATCH RFC POC 00/50] file: handle files on syscall exit

[Rob Clark]

On Tue, Sep 15, 2026 at 9:02 AM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Tue, 15 Sept 2026 at 04:31, Christian Brauner <brauner@xxxxxxxxxx> wrote:
> >
> > TL;DR, this lets arch code handle fd install and cleanup. fd_prepare()
> > allocates a descriptor like get_unused_fd_flags() does and records it in
> > a slot on the task. fd_stage() attaches the file to that slot and
> > returns the number.
>
> Honestly, I am *not* a fan. At all.
>
> I think this adds complexity rather than removing it.
>
> The diffstat tells a story:
>
> >  106 files changed, 962 insertions(+), 861 deletions(-)
>
> in how this adds a hundred lines more than it deletes.
>
> But to make things worse, it adds them in bad places: low-level
> architecture assembly code.
>
> Those extra lines are *not* making complicated code simpler. Quite the
> reverse. They are taking fairly straightforward "just deal with errors
> with normal cleanup in the place where it makes sense" and makes the
> *straightforward* case simpler, while making the big picture more
> complicated and subtle, and adding new code to places that are not
> simple and just blindly do somethign that makes no sense in that
> context.

With fd's it is more than just about error rollback.. exposing an fd
to userspace mid-way thru an ioctl is an easy security bug to write..

OTOH, "just use FD_PREPARE() / fd_publish()"..

BR,
-R