From: Ian Jackson <ian.jackson@eu.citrix.com>
Date: Mon, 5 Jan 2015 14:31:00 +0000 (+0000)
Subject: libxl: Initialise CTX->xce in domain suspend, as needed
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~4002
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=6b511af68618a86d5a2258e649042a3f0b8ace52;p=xen.git

libxl: Initialise CTX->xce in domain suspend, as needed

When excuting xl migrate/Remus, the following error can occur:
  [root@master xen]# xl migrate 5 slaver
  migration target: Ready to receive domain.
  Saving to migration stream new xl format (info 0x1/0x0/1225)
  Loading new save file <incoming migration stream> (new xl fmt info 0x1/0x0/12\
)
   Savefile contains xl domain config in JSON format
  Parsing config from <saved>
  Segmentation fault (core dumped)

This is because CTX->xce is used without been initialized.
The bug was introduced by commit 2ffeb5d7f5d8
    libxl: events: Deregister evtchn fd when not needed
which removed the initialization of xce from libxl__ctx_alloc.

In this patch we initialise the CTX->xce before using it.  Also, we
adjust the doc comment for libxl__ev_evtchn_* to mention the need to
do so.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Release-Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>
---

diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 74ea84b74a..94ae8180ed 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1824,6 +1824,9 @@ void libxl__domain_suspend(libxl__egc *egc, libxl__domain_suspend_state *dss)
     port = xs_suspend_evtchn_port(dss->domid);
 
     if (port >= 0) {
+        rc = libxl__ctx_evtchn_init(gc);
+        if (rc) goto out;
+
         dss->guest_evtchn.port =
             xc_suspend_evtchn_init_exclusive(CTX->xch, CTX->xce,
                                   dss->domid, port, &dss->guest_evtchn_lockfd);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 9695f18759..6dac0f8682 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -800,8 +800,10 @@ static inline int libxl__ev_xswatch_isregistered(const libxl__ev_xswatch *xw)
 
 /*
  * The evtchn facility is one-shot per call to libxl__ev_evtchn_wait.
- * You should call some suitable xc bind function on (or to obtain)
- * the port, then libxl__ev_evtchn_wait.
+ * You should:
+ *   Use libxl__ctx_evtchn_init to make sure CTX->xce is valid;
+ *   Call some suitable xc bind function on (or to obtain) the port;
+ *   Then call libxl__ev_evtchn_wait.
  *
  * When the event is signaled then the callback will be made, once.
  * Then you must call libxl__ev_evtchn_wait again, if desired.