[Libvir] [PATCH] avoid virsh hang due to missing virDomainFree(dom) call

[Daniel P. Berrange]

On Wed, Jan 30, 2008 at 06:25:19PM +0100, Jim Meyering wrote:
> Without the following patch, this command would hang
> 
>     printf 'domuuid fc4\ndomstate fc4\n' \
>       | ./virsh --connect test://$PWD/../docs/testnode.xml
> 
> with this stack trace:
> 
>     __lll_lock_wait ...
>     _L_lock_105 ...
>     __pthread_mutex_lock ...
>     virUnrefDomain (domain=0x6a8b30) at hash.c:884
>     virDomainFree (domain=0x6a8b30) at libvirt.c:1211
>     cmdDomstate (ctl=0x7fffea723390, cmd=0x6a8b10) at virsh.c:677
>     vshCommandRun (ctl=0x7fffea723390, cmd=0x6a8b10) at virsh.c:4033
>     main (argc=3, argv=0x7fffea7234e8) at virsh.c:501
>
> The problem is that cmdDomuuid didn't call virDomainFree(dom), so
> cmdDomstate hangs trying to do the Unref.

I don't understand why it would hang simply because it forgot to free 
an object. Surely it ought to just be a memory leak not hang ? Each
individual libvirt API must always have a matched lock & unlock pair
in all codepaths, so a hang should only occur if an unlock is missing
in some codepath. 

Dan.
-- 
|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
|=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=|