From: Yu Zhiguo <yuzg@cn.fujitsu.com>
Subject: Re: [PATCH] lowlevel: Fix Segmentation fault of xend
Date: Tue, 22 Jun 2010 08:58:32 +0800
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To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Keir Fraser <keir.fraser@eu.citrix.com>
List-Id: xen-devel@lists.xenproject.org

Hi Ian,

Ian Jackson wrote:
> 
> It is wrong to call xc_clear_last_error with a NULL xc_interface*.
> If xend is doing this it is probably a bug in the python xc lowlevel
> interface.  Can you get a stack trace please so that we can fix the
> call site ?
> 


The stack trace is
 PyXc_init()
  -> pyxc_error_to_exception(0)
   -> xc_clear_last_error()

So fix it in pyxc_error_to_exception(). Thanks for your reply.

V2 is following.

-----------------

If /proc/xen/privcmd cannot be opened,
start xend occurs Segmentation fault.
Add check to fix it.

Signed-off-by: Yu Zhiguo <yuzg@cn.fujitsu.com>

diff -r 72c6228b5f0f -r bd3bf925f4ce tools/python/xen/lowlevel/xc/xc.c
--- a/tools/python/xen/lowlevel/xc/xc.c	Mon Jun 21 19:19:25 2010 +0100
+++ b/tools/python/xen/lowlevel/xc/xc.c	Tue Jun 22 17:02:30 2010 +0800
@@ -72,7 +72,8 @@
     else
         pyerr = Py_BuildValue("(is)", err->code, desc);
 
-    xc_clear_last_error(xch);
+    if (xch)
+        xc_clear_last_error(xch);
 
     if ( pyerr != NULL )
     {