Xen devel - Jan 2011 - [PATCH] Fix stubdom-dm using "grep" improperly

stubdom-dm uses "grep" on "xm list" output to determine
whether it is
already running. The existing behavior is to use "grep $domname-dm"
but
this will result in a false-positive in the case of another domU running 
whose name ends with the full new name; for instance, if "abctest-dm"
is
running, a new "test-dm" will spin forever, waiting for it the end.

Any easy fix is to have it use "grep -w" instead of "grep",
searching
for the whole word only.

It also might be worth considering a switch to "xl list" from "xm
list",
here and in other places.

This bug appears to exist in xen-4.0-testing, as well.

Since it''s a one-liner, a signed-off may not be needed, but just in
case..

Signed-off-by: John Weekes <lists.xen@nuclearfallout.net>

--- a/xen-unstable.hg/stubdom/stubdom-dm        2010-08-10 
23:20:26.187051097 -0500
+++ b/xen-unstable.hg/stubdom/stubdom-dm        2011-01-09 
22:43:15.951806650 -0600
@@ -91,7 +91,7 @@
  ############
  # stubdomain
  # Wait for any previous stubdom to terminate
-while xm list | grep $domname-dm
+while xm list | grep -w $domname-dm
  do
         sleep 1
  done


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

On 1/9/2011 9:09 PM, John Weekes wrote:
> stubdom-dm uses "grep" on "xm list" output to determine
whether it is
> already running. The existing behavior is to use "grep
$domname-dm"
> but this will result in a false-positive in the case of another domU 
> running whose name ends with the full new name; for instance, if 
> "abctest-dm" is running, a new "test-dm" will spin
forever, waiting
> for it the end.
>
> Any easy fix is to have it use "grep -w" instead of
"grep", searching
> for the whole word only.
>
> It also might be worth considering a switch to "xl list" from
"xm
> list", here and in other places.
>
> This bug appears to exist in xen-4.0-testing, as well.
>
> Since it''s a one-liner, a signed-off may not be needed, but just
in
> case..
>
> Signed-off-by: John Weekes <lists.xen@nuclearfallout.net>
Here''s a corrected version done against the repo (i.e., with corrected 
paths).

diff -r 7b4c82f07281 stubdom/stubdom-dm
--- a/stubdom/stubdom-dm        Wed Jan 05 23:54:15 2011 +0000
+++ b/stubdom/stubdom-dm        Mon Jan 10 02:28:48 2011 -0500
@@ -91,7 +91,7 @@
  ############
  # stubdomain
  # Wait for any previous stubdom to terminate
-while xm list | grep $domname-dm
+while xm list | grep -w $domname-dm
  do
         sleep 1
  done

-John


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

John Weekes writes ("[Xen-devel] [PATCH] Fix stubdom-dm using
"grep" improperly"):
> stubdom-dm uses "grep" on "xm list" output to determine
whether it is
> already running. The existing behavior is to use "grep
$domname-dm" but
> this will result in a false-positive in the case of another domU running 
> whose name ends with the full new name; for instance, if
"abctest-dm" is
> running, a new "test-dm" will spin forever, waiting for it the
end.
Urgh.  Thanks for this patch.  This code is pretty horrid stuff, I
have to say.  I have applied your fix to xen-unstable.

Keir, can you please also commit this to 4.0-testing ?  It applies
cleanly.

Stefano: does xl in stubdom mode still use stubdom-dm ?  If so can it
please not ?  Certainly "xm list" isn''t going to work!

Ian.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

On Tue, 11 Jan 2011, Ian Jackson wrote:
> John Weekes writes ("[Xen-devel] [PATCH] Fix stubdom-dm using
"grep" improperly"):
> > stubdom-dm uses "grep" on "xm list" output to
determine whether it is
> > already running. The existing behavior is to use "grep
$domname-dm" but
> > this will result in a false-positive in the case of another domU
running
> > whose name ends with the full new name; for instance, if
"abctest-dm" is
> > running, a new "test-dm" will spin forever, waiting for it
the end.
> 
> Urgh.  Thanks for this patch.  This code is pretty horrid stuff, I
> have to say.  I have applied your fix to xen-unstable.
> 
> Keir, can you please also commit this to 4.0-testing ?  It applies
> cleanly.
> 
> Stefano: does xl in stubdom mode still use stubdom-dm ?  If so can it
> please not ?  Certainly "xm list" isn''t going to work!
It doesn''t.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

Stefano Stabellini writes ("Re: [Xen-devel] [PATCH] Fix stubdom-dm using
"grep" improperly [and 1 more
messages]"):
> On Tue, 11 Jan 2011, Ian Jackson wrote:
> > Stefano: does xl in stubdom mode still use stubdom-dm ?  If so can it
> > please not ?  Certainly "xm list" isn''t going to
work!
> 
> It doesn''t.
Yay.

Ian.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

>> Stefano: does xl in stubdom mode still use stubdom-dm ?  If so can it
>> please not ?  Certainly "xm list" isn''t going to
work!
> It doesn''t.
Actually, if anyone''s curious, I can''t get my stubdom-based
domUs to
actually start with "xl", which is part of why still use
"xm". I haven''t
had time to investigate further yet. Maybe it''s because I''m
testing with
"xm"-based domains already running, or maybe there''s a
configuration
file incompatibility.

-John

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel