On Tue, Jul 19, 2022 at 04:15:49PM +0100, Dr. David Alan Gilbert wrote:
> * Peter Xu (pet...@redhat.com) wrote:
> > Create a new socket for postcopy to be prepared to send postcopy requested
> > pages via this specific channel, so as to not get blocked by precopy pages.
> >
> > A new thread is also created on dest qemu to receive data from this new
> > channel
> > based on the ram_load_postcopy() routine.
> >
> > The ram_load_postcopy(POSTCOPY) branch and the thread has not started to
> > function, and that'll be done in follow up patches.
> >
> > Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new
> > thread too to make sure it'll be recycled properly.
>
> I'm hitting a CI failure here:
> https://gitlab.com/dagrh/qemu/-/jobs/2741659845
>
> c.o -c ../migration/migration.c
> ../migration/migration.c: In function ‘migration_ioc_process_incoming’:
> ../migration/migration.c:766:8: error: ‘start_migration’ may be used
> uninitialized in this function [-Werror=maybe-uninitialized]
> 766 | if (start_migration) {
> | ^
>
> > Reviewed-by: Daniel P. Berrang?? <berra...@redhat.com>
> > Reviewed-by: Juan Quintela <quint...@redhat.com>
> > Signed-off-by: Peter Xu <pet...@redhat.com>
> > ---
> > migration/migration.c | 62 +++++++++++++++++++++++----
> > migration/migration.h | 8 ++++
> > migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++--
> > migration/postcopy-ram.h | 10 +++++
> > migration/ram.c | 25 ++++++++---
> > migration/ram.h | 4 +-
> > migration/savevm.c | 20 ++++-----
> > migration/socket.c | 22 +++++++++-
> > migration/socket.h | 1 +
> > migration/trace-events | 5 ++-
> > 10 files changed, 218 insertions(+), 31 deletions(-)
> >
> > diff --git a/migration/migration.c b/migration/migration.c
> > index ce7bb68cdc..9484fec0b2 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void)
> > mis->page_requested = NULL;
> > }
> >
> > + if (mis->postcopy_qemufile_dst) {
> > +
> > migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
> > + qemu_fclose(mis->postcopy_qemufile_dst);
> > + mis->postcopy_qemufile_dst = NULL;
> > + }
> > +
> > yank_unregister_instance(MIGRATION_YANK_INSTANCE);
> > }
> >
> > @@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error
> > **errp)
> > migration_incoming_process();
> > }
> >
> > +static bool migration_needs_multiple_sockets(void)
> > +{
> > + return migrate_use_multifd() || migrate_postcopy_preempt();
> > +}
> > +
> > void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > {
> > MigrationIncomingState *mis = migration_incoming_get_current();
> > Error *local_err = NULL;
> > bool start_migration;
> > + QEMUFile *f;
> >
> > if (!mis->from_src_file) {
> > /* The first connection (multifd may have multiple) */
> > - QEMUFile *f = qemu_file_new_input(ioc);
> > + f = qemu_file_new_input(ioc);
> >
> > if (!migration_incoming_setup(f, errp)) {
> > return;
> > @@ -730,13 +742,18 @@ void migration_ioc_process_incoming(QIOChannel *ioc,
> > Error **errp)
> >
> > /*
> > * Common migration only needs one channel, so we can start
> > - * right now. Multifd needs more than one channel, we wait.
> > + * right now. Some features need more than one channel, we wait.
> > */
> > - start_migration = !migrate_use_multifd();
> > + start_migration = !migration_needs_multiple_sockets();
> > } else {
> > /* Multiple connections */
> > - assert(migrate_use_multifd());
> > - start_migration = multifd_recv_new_channel(ioc, &local_err);
> > + assert(migration_needs_multiple_sockets());
> > + if (migrate_use_multifd()) {
> > + start_migration = multifd_recv_new_channel(ioc, &local_err);
> > + } else if (migrate_postcopy_preempt()) {
> > + f = qemu_file_new_input(ioc);
> > + start_migration = postcopy_preempt_new_channel(mis, f);
> > + }
>
> So that doesn't always set start_migration?
Logically it should, because we asserted on
migration_needs_multiple_sockets(), while multifd and preempt mode are the
only two that may need multiple sockets. So it must go into either of
them.
A fix could be like this:
diff --git a/migration/migration.c b/migration/migration.c
index 76cf2a72c0..7c7e529ca7 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -753,7 +753,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error
**errp)
assert(migration_needs_multiple_sockets());
if (migrate_use_multifd()) {
start_migration = multifd_recv_new_channel(ioc, &local_err);
- } else if (migrate_postcopy_preempt()) {
+ } else {
+ assert(migrate_postcopy_preempt());
f = qemu_file_new_input(ioc);
start_migration = postcopy_preempt_new_channel(mis, f);
}
Or we simply set start_migration=false as initial value.
Should I repost the series?
Thanks,
--
Peter Xu
