um: virtio_uml: Fix time-travel external time propagation
authorJohannes Berg <johannes.berg@intel.com>
Thu, 16 Sep 2021 11:09:22 +0000 (13:09 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 27 Jan 2022 10:03:45 +0000 (11:03 +0100)
commita3641f64a9d9ac2fb5e17b9ebd265e9bb8c0548d
treeb523a4906f9bb917b4dcec8aced65214d3e721c9
parent4e71908ba7cb581342205a9d3b4a8b56109e3ae8
um: virtio_uml: Fix time-travel external time propagation

[ Upstream commit 85e73968a040c642fd38f6cba5b73b61f5d0f052 ]

When creating an external event, the current time needs to
be propagated to other participants of a simulation. This
is done in the places here where we kick a virtq etc.

However, it must be done for _all_ external events, and
that includes making the initial socket connection and
later closing it. Call time_travel_propagate_time() to do
this before making or closing the socket connection.

Apparently, at least for the initial connection creation,
due to the remote side in my use cases using microseconds
(rather than nanoseconds), this wasn't a problem yet; only
started failing between 5.14-rc1 and 5.15-rc1 (didn't test
others much), or possibly depending on the configuration,
where more delays happen before the virtio devices are
initialized.

Fixes: 88ce64249233 ("um: Implement time-travel=ext")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>
arch/um/drivers/virtio_uml.c