[Xen-devel] [PATCH 2/3] oxenstored: Don't re-open a xenctrl handle for every domain introduction

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Currently, an xc handle is opened in main() which is used for cleanup
activities, and a new xc handle is temporarily opened every time a domain is
introduced.  This is inefficient, and amongst other things, requires full root
privileges for the lifetime of oxenstored.

All code using the Xenctrl handle is in domains.ml, so initialise xc as a
global (now happens just before main() is called) and drop it as a parameter
from Domains.create and Domains.cleanup.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Christian Lindig <christian.lindig@xxxxxxxxxx>
---
 tools/ocaml/xenstored/domains.ml   |  6 ++++--
 tools/ocaml/xenstored/process.ml   |  3 +--
 tools/ocaml/xenstored/xenstored.ml | 10 +++-------
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
index 4134630..71dde16 100644
--- a/tools/ocaml/xenstored/domains.ml
+++ b/tools/ocaml/xenstored/domains.ml
@@ -18,6 +18,8 @@ let debug fmt = Logging.debug "domains" fmt
 let error fmt = Logging.error "domains" fmt
 let warn fmt  = Logging.warn  "domains" fmt
 
+let xc = Xenctrl.interface_open ()
+
 type domains = {
        eventchn: Event.t;
        table: (Xenctrl.domid, Domain.t) Hashtbl.t;
@@ -86,7 +88,7 @@ let remove_from_queue dom queue =
                | None -> ()
                | Some x -> if x=dom then d := None) queue
 
-let cleanup xc doms =
+let cleanup doms =
        let notify = ref false in
        let dead_dom = ref [] in
 
@@ -120,7 +122,7 @@ let cleanup xc doms =
 let resume doms domid =
        ()
 
-let create xc doms domid mfn port =
+let create doms domid mfn port =
        let interface = Xenctrl.map_foreign_range xc domid 
(Xenmmap.getpagesize()) mfn in
        let dom = Domain.make domid mfn port interface doms.eventchn in
        Hashtbl.add doms.table domid dom;
diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
index 217a344..977e7c1 100644
--- a/tools/ocaml/xenstored/process.ml
+++ b/tools/ocaml/xenstored/process.ml
@@ -410,8 +410,7 @@ let do_introduce con t domains cons data =
                if Domains.exist domains domid then
                        Domains.find domains domid
                else try
-                       let ndom = Xenctrl.with_intf (fun xc ->
-                               Domains.create xc domains domid mfn port) in
+                       let ndom = Domains.create domains domid mfn port in
                        Connections.add_domain cons ndom;
                        Connections.fire_spec_watches cons "@introduceDomain";
                        ndom
diff --git a/tools/ocaml/xenstored/xenstored.ml 
b/tools/ocaml/xenstored/xenstored.ml
index 40a05e9..7df02ed 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -177,12 +177,11 @@ let from_channel_f chan domain_f watch_f store_f =
 let from_channel store cons doms chan =
        (* don't let the permission get on our way, full perm ! *)
        let op = Store.get_ops store Perms.Connection.full_rights in
-       let xc = Xenctrl.interface_open () in
 
        let domain_f domid mfn port =
                let ndom =
                        if domid > 0 then
-                               Domains.create xc doms domid mfn port
+                               Domains.create doms domid mfn port
                        else
                                Domains.create0 doms
                        in
@@ -196,8 +195,7 @@ let from_channel store cons doms chan =
                op.Store.write path value;
                op.Store.setperms path perms
                in
-       finally (fun () -> from_channel_f chan domain_f watch_f store_f)
-               (fun () -> Xenctrl.interface_close xc)
+       from_channel_f chan domain_f watch_f store_f
 
 let from_file store cons doms file =
        let channel = open_in file in
@@ -328,8 +326,6 @@ let _ =
                (if cf.domain_init then [ Event.fd eventchn ] else [])
                in
 
-       let xc = Xenctrl.interface_open () in
-
        let process_special_fds rset =
                let accept_connection can_write fd =
                        let (cfd, addr) = Unix.accept fd in
@@ -340,7 +336,7 @@ let _ =
                        debug "pending port %d" (Xeneventchn.to_int port);
                        finally (fun () ->
                                if Some port = eventchn.Event.virq_port then (
-                                       let (notify, deaddom) = Domains.cleanup 
xc domains in
+                                       let (notify, deaddom) = Domains.cleanup 
domains in
                                        List.iter (Connections.del_domain cons) 
deaddom;
                                        if deaddom <> [] || notify then
                                                Connections.fire_spec_watches 
cons "@releaseDomain"
-- 
2.1.4


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