Re: [PATCH v5 07/22] liveupdate: luo_ioctl: add user interface

[Pasha Tatashin]

On Fri, Nov 14, 2025 at 7:58 AM Mike Rapoport <rppt@xxxxxxxxxx> wrote:
>
> On Fri, Nov 07, 2025 at 04:03:05PM -0500, Pasha Tatashin wrote:
> > Introduce the user-space interface for the Live Update Orchestrator
> > via ioctl commands, enabling external control over the live update
> > process and management of preserved resources.
> >
> > The idea is that there is going to be a single userspace agent driving
> > the live update, therefore, only a single process can ever hold this
> > device opened at a time.
> >
> > The following ioctl commands are introduced:
> >
> > LIVEUPDATE_IOCTL_CREATE_SESSION
> > Provides a way for userspace to create a named session for grouping file
> > descriptors that need to be preserved. It returns a new file descriptor
> > representing the session.
> >
> > LIVEUPDATE_IOCTL_RETRIEVE_SESSION
> > Allows the userspace agent in the new kernel to reclaim a preserved
> > session by its name, receiving a new file descriptor to manage the
> > restored resources.
> >
> > Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> > ---
> >  include/uapi/linux/liveupdate.h  |  64 ++++++++++++
> >  kernel/liveupdate/luo_internal.h |  21 ++++
> >  kernel/liveupdate/luo_ioctl.c    | 173 +++++++++++++++++++++++++++++++
> >  3 files changed, 258 insertions(+)
>
> ...
>
> > +static int luo_ioctl_create_session(struct luo_ucmd *ucmd)
> > +{
> > +     struct liveupdate_ioctl_create_session *argp = ucmd->cmd;
> > +     struct file *file;
> > +     int ret;
> > +
> > +     argp->fd = get_unused_fd_flags(O_CLOEXEC);
> > +     if (argp->fd < 0)
> > +             return argp->fd;
> > +
> > +     ret = luo_session_create(argp->name, &file);
> > +     if (ret)
>
>                 put_unused_fd(fd) ?

Yes, thank you.

>
> > +             return ret;
> > +
> > +     ret = luo_ucmd_respond(ucmd, sizeof(*argp));
> > +     if (ret) {
> > +             fput(file);
> > +             put_unused_fd(argp->fd);
> > +             return ret;
> > +     }
>
> I think that using gotos for error handling is more appropriate here.

Sure, I will do that

>
> > +
> > +     fd_install(argp->fd, file);
> > +
> > +     return 0;
> > +}
> > +
> > +static int luo_ioctl_retrieve_session(struct luo_ucmd *ucmd)
> > +{
> > +     struct liveupdate_ioctl_retrieve_session *argp = ucmd->cmd;
> > +     struct file *file;
> > +     int ret;
> > +
> > +     argp->fd = get_unused_fd_flags(O_CLOEXEC);
> > +     if (argp->fd < 0)
> > +             return argp->fd;
> > +
> > +     ret = luo_session_retrieve(argp->name, &file);
> > +     if (ret < 0) {
> > +             put_unused_fd(argp->fd);
> > +
> > +             return ret;
> > +     }
> > +
> > +     ret = luo_ucmd_respond(ucmd, sizeof(*argp));
> > +     if (ret) {
> > +             fput(file);
> > +             put_unused_fd(argp->fd);
> > +             return ret;
> > +     }
>
> and here.

Sure

>
> > +
> > +     fd_install(argp->fd, file);
> > +
> > +     return 0;
> > +}
> > +
>
> --
> Sincerely yours,
> Mike.