[RFC PATCH 0/4] crypto,io,migration: Add support to gnutls_bye()

[Fabiano Rosas <farosas@suse.de>]

Hi,

We've been discussing a way to stop multifd recv threads from getting
an error at the end of migration when the source threads close the
iochannel without ending the TLS session.

The original issue was introduced by commit 1d457daf86
("migration/multifd: Further remove the SYNC on complete") which
altered the synchronization of the source and destination in a manner
that causes the destination to already be waiting at recv() when the
source closes the connection.

One approach would be to issue gnutls_bye() at the source after all
the data has been sent. The destination would then gracefully exit
when it gets EOF.

Aside from stopping the recv thread from seeing an error, this also
creates a contract that all connections should be closed only after
the TLS session is ended. This helps to avoid masking a legitimate
issue where the connection is closed prematurely.

Fabiano Rosas (4):
  crypto: Allow gracefully ending the TLS session
  io: tls: Add qio_channel_tls_bye
  migration/multifd: Terminate the TLS connection
  migration: Check migration error after loadvm

 crypto/tlssession.c         | 40 ++++++++++++++++++
 include/crypto/tlssession.h | 22 ++++++++++
 include/io/channel-tls.h    | 12 ++++++
 io/channel-tls.c            | 84 +++++++++++++++++++++++++++++++++++++
 io/trace-events             |  5 +++
 migration/multifd.c         | 34 ++++++++++++++-
 migration/savevm.c          |  6 ++-
 migration/tls.c             |  5 +++
 migration/tls.h             |  2 +-
 9 files changed, 207 insertions(+), 3 deletions(-)

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2.35.3