Re: [PATCH 2/2] migration/multifd: Drop registered_yank

[Fabiano Rosas <farosas@suse.de>]

Peter Xu <peterx@redhat.com> writes:

> On Thu, Feb 08, 2024 at 09:48:33AM -0300, Fabiano Rosas wrote:
>> peterx@redhat.com writes:
>> 
>> > From: Peter Xu <peterx@redhat.com>
>> >
>> > With a clear definition of p->c protocol, where we only set it up if the
>> > channel is fully established (TLS or non-TLS), registered_yank boolean will
>> > have equal meaning of "p->c != NULL".
>> >
>> > Drop registered_yank by checking p->c instead.
>> >
>> > Reviewed-by: Fabiano Rosas <farosas@suse.de>
>> > Signed-off-by: Peter Xu <peterx@redhat.com>
>> > ---
>> >  migration/multifd.h | 2 --
>> >  migration/multifd.c | 7 +++----
>> >  2 files changed, 3 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/migration/multifd.h b/migration/multifd.h
>> > index 8a1cad0996..b3fe27ae93 100644
>> > --- a/migration/multifd.h
>> > +++ b/migration/multifd.h
>> > @@ -78,8 +78,6 @@ typedef struct {
>> >      bool tls_thread_created;
>> >      /* communication channel */
>> >      QIOChannel *c;
>> > -    /* is the yank function registered */
>> > -    bool registered_yank;
>> >      /* packet allocated len */
>> >      uint32_t packet_len;
>> >      /* guest page size */
>> > diff --git a/migration/multifd.c b/migration/multifd.c
>> > index 4a85a6b7b3..278453cf84 100644
>> > --- a/migration/multifd.c
>> > +++ b/migration/multifd.c
>> > @@ -648,11 +648,11 @@ static int multifd_send_channel_destroy(QIOChannel *send)
>> >  
>> >  static bool multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp)
>> >  {
>> > -    if (p->registered_yank) {
>> > +    if (p->c) {
>> >          migration_ioc_unregister_yank(p->c);
>> > +        multifd_send_channel_destroy(p->c);
>> 
>> At socket_send_channel_destroy the clean up of outgoing_args.saddr will
>> now be skipped. The failure at multifd_new_send_channel_async might have
>> been due to TLS, in which case all of plain socket setup will have
>> happened properly.
>
> Right, IMHO it's a hack to free globals in a per-channel helper.  We should
> have moved:
>
>     if (outgoing_args.saddr) {
>         qapi_free_SocketAddress(outgoing_args.saddr);
>         outgoing_args.saddr = NULL;
>     }
>
> Outside irrelevant of that..
>
> That could be done later I guess, because we have one more guard:
>
> socket_start_outgoing_migration():
>     /* in case previous migration leaked it */
>     qapi_free_SocketAddress(outgoing_args.saddr);
>     outgoing_args.saddr = addr;
>
> If you think proper, I can add one more patch to do that cleanup, IOW, move
> above free() into multifd_send_cleanup_state().

Sounds good.

>
> Thanks,