| Message ID | 20210629181356.217312-2-peterx@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | migration: Two fixes around yank and postcopy recovery | expand |
* Peter Xu (peterx@redhat.com) wrote: > Starting from commit b5eea99ec2f5c, qmp_migrate_recover() calls unregister > before calling qemu_start_incoming_migration(). I believe it wanted to mitigate > the next call to yank_register_instance(), but I think that's wrong. > > Firstly, if during recover, we should keep the yank instance there, not > "quickly removing and adding it back". > > Meanwhile, calling qmp_migrate_recover() twice with b5eea99ec2f5c will directly > crash the dest qemu (right now it can't; but it'll start to work right after > the next patch) because the 1st call of qmp_migrate_recover() will unregister > permanently when the channel failed to establish, then the 2nd call of > qmp_migrate_recover() crashes at yank_unregister_instance(). > > This patch fixes it by moving yank ops out of qemu_start_incoming_migration() > into qmp_migrate_incoming. For qmp_migrate_recover(), drop the unregister of > yank instance too since we keep it there during the recovery phase. > > Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/migration.c | 11 +++++------ > 1 file changed, 5 insertions(+), 6 deletions(-) > > diff --git a/migration/migration.c b/migration/migration.c > index 4228635d18..1bb03d1eca 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -456,10 +456,6 @@ static void qemu_start_incoming_migration(const char *uri, Error **errp) > { > const char *p = NULL; > > - if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) { > - return; > - } > - > qapi_event_send_migration(MIGRATION_STATUS_SETUP); > if (strstart(uri, "tcp:", &p) || > strstart(uri, "unix:", NULL) || > @@ -474,7 +470,6 @@ static void qemu_start_incoming_migration(const char *uri, Error **errp) > } else if (strstart(uri, "fd:", &p)) { > fd_start_incoming_migration(p, errp); > } else { > - yank_unregister_instance(MIGRATION_YANK_INSTANCE); > error_setg(errp, "unknown migration protocol: %s", uri); > } > } > @@ -2083,9 +2078,14 @@ void qmp_migrate_incoming(const char *uri, Error **errp) > return; > } > > + if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) { > + return; > + } > + > qemu_start_incoming_migration(uri, &local_err); > > if (local_err) { > + yank_unregister_instance(MIGRATION_YANK_INSTANCE); > error_propagate(errp, local_err); > return; > } > @@ -2114,7 +2114,6 @@ void qmp_migrate_recover(const char *uri, Error **errp) > * only re-setup the migration stream and poke existing migration > * to continue using that newly established channel. > */ > - yank_unregister_instance(MIGRATION_YANK_INSTANCE); > qemu_start_incoming_migration(uri, errp); > } > > -- > 2.31.1 >
diff --git a/migration/migration.c b/migration/migration.c index 4228635d18..1bb03d1eca 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -456,10 +456,6 @@ static void qemu_start_incoming_migration(const char *uri, Error **errp) { const char *p = NULL; - if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) { - return; - } - qapi_event_send_migration(MIGRATION_STATUS_SETUP); if (strstart(uri, "tcp:", &p) || strstart(uri, "unix:", NULL) || @@ -474,7 +470,6 @@ static void qemu_start_incoming_migration(const char *uri, Error **errp) } else if (strstart(uri, "fd:", &p)) { fd_start_incoming_migration(p, errp); } else { - yank_unregister_instance(MIGRATION_YANK_INSTANCE); error_setg(errp, "unknown migration protocol: %s", uri); } } @@ -2083,9 +2078,14 @@ void qmp_migrate_incoming(const char *uri, Error **errp) return; } + if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) { + return; + } + qemu_start_incoming_migration(uri, &local_err); if (local_err) { + yank_unregister_instance(MIGRATION_YANK_INSTANCE); error_propagate(errp, local_err); return; } @@ -2114,7 +2114,6 @@ void qmp_migrate_recover(const char *uri, Error **errp) * only re-setup the migration stream and poke existing migration * to continue using that newly established channel. */ - yank_unregister_instance(MIGRATION_YANK_INSTANCE); qemu_start_incoming_migration(uri, errp); }
Starting from commit b5eea99ec2f5c, qmp_migrate_recover() calls unregister before calling qemu_start_incoming_migration(). I believe it wanted to mitigate the next call to yank_register_instance(), but I think that's wrong. Firstly, if during recover, we should keep the yank instance there, not "quickly removing and adding it back". Meanwhile, calling qmp_migrate_recover() twice with b5eea99ec2f5c will directly crash the dest qemu (right now it can't; but it'll start to work right after the next patch) because the 1st call of qmp_migrate_recover() will unregister permanently when the channel failed to establish, then the 2nd call of qmp_migrate_recover() crashes at yank_unregister_instance(). This patch fixes it by moving yank ops out of qemu_start_incoming_migration() into qmp_migrate_incoming. For qmp_migrate_recover(), drop the unregister of yank instance too since we keep it there during the recovery phase. Signed-off-by: Peter Xu <peterx@redhat.com> --- migration/migration.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)