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

Mike Rapoport
2025-11-14T12:58:04Z

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@soleen.com>
> ---
> 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) ?

> + 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.

> +
> + 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.

> +
> + fd_install(argp->fd, file);
> +
> + return 0;
> +}
> +

--
Sincerely yours,
Mike.