Re: [PATCH v11 09/10] migration: Implement MigrateChannelList to hmp migration flow.

[Het Gala]

On 10/4/2023 8:55 PM, Fabiano Rosas wrote:

> Het Gala <het.gala@nutanix.com> writes:
>
> > Integrate MigrateChannelList with all transport backends
> > (socket, exec and rdma) for both src and dest migration
> > endpoints for hmp migration.
> >
> > Suggested-by: Aravind Retnakaran <aravind.retnakaran@nutanix.com>
> > Signed-off-by: Het Gala <het.gala@nutanix.com>
> > Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> > ---
> >  migration/migration-hmp-cmds.c | 15 +++++++++++++--
> >  migration/migration.c          |  5 ++---
> >  migration/migration.h          |  3 ++-
> >  3 files changed, 17 insertions(+), 6 deletions(-)
> >
> > diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
> > index a2e6a5c51e..a1657f3d37 100644
> > --- a/migration/migration-hmp-cmds.c
> > +++ b/migration/migration-hmp-cmds.c
> > @@ -441,9 +441,14 @@ void hmp_migrate_incoming(Monitor *mon, const QDict *qdict)
> >  {
> >      Error *err = NULL;
> >      const char *uri = qdict_get_str(qdict, "uri");
> > +    MigrationChannelList *caps = NULL;
> > +    g_autoptr(MigrationChannel) channel = g_new0(MigrationChannel, 1);
> >       
> Just the pointer here. If I remember correctly the g_autoptr here would
> cause a double free when freeing the caps.
>

Yes, we'll just have 'g_autoptr(MigrationChannel) channel = NULL'.

Is it because inside QAPI_LIST_PREPEND, caps will be refrencing to the same memory as 'channel', we don't need to free channel ? I am still not sure what is the right place to use g_steal_pointer(), is this a right place to use (non-error paths) ?

> >  
> > -    qmp_migrate_incoming(uri, false, NULL, &err);
> > +    migrate_uri_parse(uri, &channel, &err);
> > +    QAPI_LIST_PREPEND(caps, channel);
> >  
> > +    qmp_migrate_incoming(NULL, true, caps, &err);
> > +    qapi_free_MigrationChannelList(caps);
> >      hmp_handle_error(mon, err);
> >  }
> >  
> > @@ -730,9 +735,15 @@ void hmp_migrate(Monitor *mon, const QDict *qdict)
> >      bool resume = qdict_get_try_bool(qdict, "resume", false);
> >      const char *uri = qdict_get_str(qdict, "uri");
> >      Error *err = NULL;
> > +    MigrationChannelList *caps = NULL;
> > +    g_autoptr(MigrationChannel) channel = g_new0(MigrationChannel, 1);
> >       
> Same here. We free the channel via caps and we attribute it below, no
> need to allocate.
>     
    Ack.

> >  
> > -    qmp_migrate(uri, false, NULL, !!blk, blk, !!inc, inc,
> > +    migrate_uri_parse(uri, &channel, &err);
> > +    QAPI_LIST_PREPEND(caps, channel);
> > +
> > +    qmp_migrate(NULL, true, caps, !!blk, blk, !!inc, inc,
> >                   false, false, true, resume, &err);
> > +    qapi_free_MigrationChannelList(caps);
> >      if (hmp_handle_error(mon, err)) {
> >       
>     
    Regards,
    Het Gala