On 04/10/2012 07:29 AM, Peter Krempa wrote:
The new safe console handling introduced a possibility to deadlock the qemu driver when a new console connection forcibly disconnects a previous console stream that belongs to an already closed connection.
The virStreamFree function calls subsequently a the virReleaseConnect function that tries to lock the driver while discarding the connection, but the driver was already locked in qemuDomainOpenConsole.
* src/qemu/qemu_driver.c: qemuDomainOpenConsole() -- unlock the qemu driver right after acquiring the domain object --- Found while writing tests for the libvirt-test-API, its 100% reproducible:
1: Start a domain with serial console and run "cat" on this console 2: download python reproducer: http://files.pipo.sk/console_deadlock.py 3: set guest name in the script 4: run the reproducer and "virsh console 'guestname' --force" after that 5: <deadlocked>
src/qemu/qemu_driver.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
ACK; the rest of the function does not refer to driver, so moving the unlock sooner is safe. -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org