[PATCH for-4.17] tools/oxenstored: Fix Oxenstored Live Update

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

tl;dr This hunk was part of the patch emailed to xen-devel, but was missing
from what ultimately got committed.

https://lore.kernel.org/xen-devel/4164cb728313c3b9fc38cf5e9ecb790ac93a9600.1610748224.git.edvin.torok@xxxxxxxxxx/
is the patch in question, but was part of a series that had threading issues.
I have a vague recollection that I sourced the commits from a local branch,
which clearly wasn't as up-to-date as I had thought.

Either way, it's my fault/mistake, and this hunk should have been part of what
got comitted.

Fixes: 00c48f57ab36 ("tools/oxenstored: Start live update process")
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Christian Lindig <christian.lindig@xxxxxxxxxx>
CC: David Scott <dave@xxxxxxxxxx>
CC: Edwin Torok <edvin.torok@xxxxxxxxxx>
CC: Rob Hoes <Rob.Hoes@xxxxxxxxxx>
CC: Henry Wang <Henry.Wang@xxxxxxx>

Found while reviewing the XenServer patchqueue.  This is low risk for 4.17 and
fixes a feature which we thought had been working since 4.15.
---
 tools/ocaml/xenstored/xenstored.ml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/ocaml/xenstored/xenstored.ml 
b/tools/ocaml/xenstored/xenstored.ml
index d44ae673c42a..fc90fcdeb5d6 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -352,6 +352,11 @@ let _ =
                rw_sock
        ) in
 
+       (* required for xenstore-control to detect availability of live-update 
*)
+       Store.mkdir store Perms.Connection.full_rights (Store.Path.of_string 
"/tool");
+       Store.write store Perms.Connection.full_rights
+               (Store.Path.of_string "/tool/xenstored") Sys.executable_name;
+
        Sys.set_signal Sys.sighup (Sys.Signal_handle sighup_handler);
        Sys.set_signal Sys.sigterm (Sys.Signal_handle (fun _ ->
                info "Received SIGTERM";
-- 
2.11.0