On Fri, Jan 30, 2009 at 07:00:07PM +0100, Jim Meyering wrote:
"Daniel P. Berrange" <berrange@redhat.com> wrote:
The recent refactoring of the QEMU startup process now reads the monitor TTY from the logfile. Unfortunately in this refactoring we lost the check for the 'ret == 0' scenario in the read() return value. So if QEMU quits at startup, eg due to missing disk image, we loop forever on read() == 0 because we hit end-of-file and QEMU has quit.
This patch adds back handling for this scenario, and takes care to propagate the contents of the log to the user as an error message
# start demo libvir: QEMU error : internal error unable to start guest: qemu: could not open disk image /home/berrange/Fedora-9-i686-Live.iso error: Failed to start domain demo
In addition, there were a couple of other bugs
- a memory leak where we set the 'monitorpath' variable, even though we'd just set it moments before.
- a missing check for whether the driver VNC password was present when initializing passwords at VM startupo
- missing initialization of the monitor_watch field, and missing checking for whether the watch was set before removing it.
- a gratuitous LOG_INFO when shutting down any VM, which could just be LOG_DEBUG.
FYI, I reproduced the infloop with the following:
cat <<\EOF > d.xml <domain type='qemu'> <name>D</name> <uuid>c7a5fdbd-cdaf-9455-926a-d65c16db1809</uuid> <memory>219200</memory> <currentMemory>219200</currentMemory> <vcpu>2</vcpu> <os> <type arch='i686' machine='pc'>hvm</type> <boot dev='cdrom'/> </os> <devices> <emulator>/usr/bin/qemu-system-x86_64</emulator> <disk type='file' device='cdrom'> <source file='no-such-file'/> <target dev='hdc'/> <readonly/> </disk> <disk type='file' device='disk'> <source file='no-such-file'/> <target dev='hda'/> </disk> <graphics type='vnc' port='-1'/> </devices> </domain> EOF
Before, this use of virsh would hang:
qemud/libvirtd & src/virsh -c qemu:///session "define d.xml; start D"
Now, it fails with a diagnostic, as you'd expect.
FWIW, any scenario where the XML points to a disk image that doesn't exist should hit the codepath I did. That said it wasn't 100% reliable but I put that down to the LXC corruption in valgrind i posted.
Somehow, while testing this, I got numerous segfaults from libvirtd (due to dereferencing NULL doms->objs[i]->def, but those should never be NULL), yet when I went to set up a reproducer, it stopped happening altogether.
It shouldn't be possible to allocate a virDomainObjPtr instance without having a valid virDomainDefPtr instance. That said, it could be the case that the doms->objs[i] access is doing an array out of bounds access, due to inadequate thread locking, or a bogus re-allocation This patch is applied to CVS. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|