[PATCH v3 0/5] util/qemu-sockets: Introduce inet socket options controlling TCP keep-alive

[Juraj Marcin <jmarcin@redhat.com>]

This series extends the work introduced by commit aec21d3175 ("qapi: Add
InetSocketAddress member keep-alive"). [1]

First, the series fixes an issue in qio_dns_resolver_lookup_sync_inet(),
where the InetSocketAddress structure is only partially copied. Next, it
refactors setting client socket options into a separate function and the
success and failure paths in inet_listen_saddr() in preparation for
keep-alive support on server sockets and the addition of new TCP
keep-alive options.

Then, the series adds support for keep-alive on server sockets and adds
three new InetSocketAddress options for control of TCP keep-alive
settings. By default, the value of all new settings is 0, which means no
custom socket option value is set.

This is useful, for example, for live migration. In case there is no
traffic from the destination to the source machine during postcopy, the
destination cannot detect a failed connection due to a lack of
non-acknowledged packets and stays in the postcopy-active state until
paused by the management of the QEMU instance.

[1]: https://lore.kernel.org/all/20190725094937.32454-1-vsementsov@virtuozzo.com/

---
V3:
- moved the InetSocketAddress struct copy fix and the common function
  setting socket options into a separate commit
- refactored inet_listen_saddr()

V2:
- moved socket options setting into a common function for both server
  and client sockets (suggested by Vladimir)

Juraj Marcin (5):
  io: Fix partial struct copy in qio_dns_resolver_lookup_sync_inet()
  util/qemu-sockets: Refactor setting client sockopts into a separate
    function
  util/qemu-sockets: Refactor success and failure paths in
    inet_listen_saddr()
  util/qemu-sockets: Add support for keep-alive flag to passive sockets
  utils/qemu-sockets: Introduce inet socket options controlling TCP
    keep-alive

 io/dns-resolver.c   |  21 ++----
 meson.build         |   6 ++
 qapi/sockets.json   |  19 ++++-
 util/qemu-sockets.c | 177 ++++++++++++++++++++++++++++++++++----------
 4 files changed, 165 insertions(+), 58 deletions(-)

-- 
2.48.1