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 09:53:59 +0000 (10:53 +0100)
commit1a2241ad400b8d7b8f1a1adef5c5b67829a63934
tree0c30d9e733ee451a918103957fc0277e357c0c84
parent8411722e5652c37b36cfa56640c7e67c0d0306ff
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