Moving data reception of the perform phase of migration to a
thread introduces a race with the finish phase, where checking
if the domain is active races with the thread finishing the
perform phase. The race is easily solved by acquiring a job in
the finish phase, which must wait for the perform phase job to
complete.
While wrapping the finish phase in a job, noticed the virDomainObj
was being unlocked in a callee - libxlDomainMigrationFinish. Move
the unlocking to libxlDomainMigrateFinish3Params, where the lock
is acquired.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
The libxl driver receives migration data within an IO callback invoked
by the event loop, effectively disabling the event loop while migration
occurs.
This patch moves receving of the migration data to a thread. The
incoming connection is still accepted in the IO callback, but control
is immediately returned to the event loop after spawning the thread.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
With all the changes in my previous foray into this code, I forgot to
remove the libxlDomainEventQueue(driver, event); call inside the
dom == NULL condition.
Signed-off-by: John Ferlan <jferlan@redhat.com>
Coverity noted that all callers to libxlDomainEventQueue() could ensure
the second parameter (event) was true before calling except this case.
As I look at the code and how events are used - it seems that prior to
generating an event for the dom == NULL condition, the resume/suspend
event should be queue'd after the virDomainSaveStatus() call which will
goto cleanup and queue the saved event anyway.
Signed-off-by: John Ferlan <jferlan@redhat.com>
In libxlDomainMigrationPrepare() if the uri_in is false, then
'hostname' is allocated and used "generically" in the routine,
but not freed. Conversely, if uri_in is true, then a uri is
allocated and hostname is set to the uri->hostname value and
likewise generically used.
At function exit, hostname wasn't free'd in the !uri_in path,
so that was added. To just make it clearer on usage the else
path became the call to virURIFree() although I suppose technically
it didn't have to since it would be a call using (NULL)
In libxlDomainMigrationConfirm(), a transient domain is removed
from the domain list after successful migration. Later in cleanup,
the domain object is unlocked, resulting in a crash
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fb4208ed700 (LWP 12044)]
0x00007fb4267251e6 in virClassIsDerivedFrom (klass=0xdeadbeef,
parent=0x7fb42830d0c0) at util/virobject.c:169
169 if (klass->magic == parent->magic)
(gdb) bt
0 0x00007fb4267251e6 in virClassIsDerivedFrom (klass=0xdeadbeef,
parent=0x7fb42830d0c0) at util/virobject.c:169
1 0x00007fb42672591b in virObjectIsClass (anyobj=0x7fb4100082b0,
klass=0x7fb42830d0c0) at util/virobject.c:365
2 0x00007fb42672583c in virObjectUnlock (anyobj=0x7fb4100082b0)
at util/virobject.c:338
3 0x00007fb41a8c7d7a in libxlDomainMigrationConfirm (driver=0x7fb4100404c0,
vm=0x7fb4100082b0, flags=1, cancelled=0) at libxl/libxl_migration.c:583
Fix by setting the virDomainObjPtr to NULL after removing it from
the domain list.
During migration, the libxl driver starts a modify job in the
begin phase, ending the job in the confirm phase. This is
essentially VIR_MIGRATE_CHANGE_PROTECTION semantics, but the
driver does not support that flag. Without CHANGE_PROTECTION
support, the job would never be terminated in error conditions
where migrate confirm phase is not executed. Further attempts
to modify the domain would result in failure to acquire a job
after LIBXL_JOB_WAIT_TIME.
Similar to the qemu driver, end the job in the begin phase.
Protecting the domain object across all phases of migration can
be done in a future patch adding CHANGE_PROTECTION support.
In libxlDomainMigrationPrepare(), a new virDomainObj is created
from the incoming domain def and added to the driver's domain
list, but never removed if there are subsequent failures during
the prepare phase.
targethost# virsh list --all
sourcehost# virsh migrate --live dom xen+ssh://targethost/system
error: operation failed: Fail to create socket for incoming migration.
targethost# virsh list --all
error: Failed to list domains
error: name in virGetDomain must not be NULL
After adding code to remove the domain on prepare failure, noticed
that libvirtd crashed due to double free of the virDomainDef. Similar
to the qemu driver, pass a pointer to virDomainDefPtr so it can be set
to NULL once a virDomainObj is created from it.
Migration code specifies the problematic non-cooperative resume mode
which is a known issue with Xen's libxl [1]. Instead, use the better
supported cooperative mode.
Without this, guests BUG() in xen_irq_resume after failing to bind
still-bound event channels.
[1] http://bugs.xenproject.org/xen/bug/30
This patch adds initial migration support to the libxl driver,
using the VIR_DRV_FEATURE_MIGRATION_PARAMS family of migration
functions.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
