On Thu, Jun 17, 2010 at 12:29:34AM +0200, Matthias Bolte wrote: > 2010/6/16 Daniel P. Berrange <berrange@xxxxxxxxxx>: > > On Sat, Jun 12, 2010 at 06:32:55PM +0200, Matthias Bolte wrote: > >> Justin Clift reported a problem with adding virStoragePoolIsPersistent > >> to virsh's pool-info command, resulting in a strange problem. Here's > >> an example: > >> > >> virsh # pool-create-as images_dir3 dir - - - - "/home/images2" > >> Pool images_dir3 created > >> > >> virsh # pool-info images_dir3 > >> Name: images_dir3 > >> UUID: 90301885-94eb-4ca7-14c2-f30b25a29a36 > >> State: running > >> Capacity: 395.20 GB > >> Allocation: 30.88 GB > >> Available: 364.33 GB > >> > >> virsh # pool-destroy images_dir3 > >> Pool images_dir3 destroyed > >> > >> At this point the images_dir3 pool should be gone (because it was > >> transient) and we should be able to create a new pool with the same name: > >> > >> virsh # pool-create-as images_dir3 dir - - - - "/home/images2" > >> Pool images_dir3 created > >> > >> virsh # pool-info images_dir3 > >> Name: images_dir3 > >> UUID: 90301885-94eb-4ca7-14c2-f30b25a29a36 > >> error: Storage pool not found > >> > >> The new pool got the same UUID as the first one, but we didn't specify > >> one. libvirt should have picked a random UUID, but it didn't. > >> > >> It turned out that virStoragePoolIsPersistent leaks a reference to the > >> storage pool object (actually remoteDispatchStoragePoolIsPersistent does). > >> As a result, pool-destroy doesn't remove the virStoragePool for the > >> "images_dir3" pool from the virConnectPtr's storagePools hash on libvirtd's > >> side. Then the second pool-create-as get's the stale virStoragePool object > >> associated with the "images_dir3" name. But this object has the old UUID. > >> > >> This commit ensures that all get_nonnull_* and make_nonnull_* calls for > >> libvirt objects are matched properly with vir*Free calls. This fixes the > >> reference leaks and the reported problem. > >> > >> All remoteDispatch*IsActive and remoteDispatch*IsPersistent functions were > >> affected. But also remoteDispatchDomainMigrateFinish2 was affected in the > >> success path. I wonder why that didn't surface earlier. Probably because > >> domainMigrateFinish2 is executed on the destination host and in the common > >> case this connection is opened especially for the migration and gets closed > >> after the migration is done. So there was no chance to run into a problem > >> because of the leaked reference. > > > > ACK, looks good. > > > > Wonder why coverity hadn't flagged these memory leaks before.. > > > > Daniel > > > > Probably because the reference leak doesn't result in a memory leak. > The old virStoragePool objects in the virConnectPtr's storagePools > hash are freed in virReleaseConnect. But every virStoragePool object created, takes a reference on the virConnectPtr. So if you leak a virStoragePool, you leak a virConnectPtr too. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list