linux-kernel - Re: [PATCH v4 14/30] liveupdate: luo_session: Add ioctls for file preservation and state management

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Message-ID: <CALzav=frK48c1=nsbVJ4EvqqOqr33pUArP4G17su0hxOYveALw@mail.gmail.com>
Date: Wed, 29 Oct 2025 14:13:20 -0700
From: David Matlack <dmatlack@...gle.com>
To: Pasha Tatashin <pasha.tatashin@...een.com>
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Subject: Re: [PATCH v4 14/30] liveupdate: luo_session: Add ioctls for file
 preservation and state management

On Wed, Oct 29, 2025 at 1:13 PM Pasha Tatashin
<pasha.tatashin@...een.com> wrote:

> Simplified uAPI Proposal
> The simplest uAPI would look like this:
> IOCTLs on /dev/liveupdate (to create and retrieve session FDs):
> LIVEUPDATE_IOCTL_CREATE_SESSION
> LIVEUPDATE_IOCTL_RETRIEVE_SESSION

> - If everything succeeds, the session becomes an empty "outgoing"
> session. It can then be closed and discarded or reused for the next
> live update by preserving new FDs into it.

I think it would be useful to cleanly separate incoming and outgoing
sessions. The only way to get an outgoing session is with
LIVEUPDATE_IOCTL_CREATE_SESSION. Incoming sessions can be retrieved
with LIVEUPDATE_IOCTL_RETRIEVE_SESSION.

It is fine and expected for incoming and outgoing sessions to have the
same name. But they are different sessions. This way, the kernel can
easily keep track of incoming and outgoing sessions separately, and
there is not need to "transition" and session from incoming to
outgoing.