This is an attempt to workaround a kernel data race spotted in #1275.
We have to delay our VFIO interraction until after the kernel handles
the PCIe hotremoval. Otherwise we risk having a deadlock inside the
kernel. We could put a dummy delay in SPDK hotremove routine, but we
don't know exactly how long we have to wait, so wait for the VFIO
hotremove notification to arrive instead. From what I understand it
is always sent after the kerner already releases the critical locks.
This patch breaks hotremove for VFIO devices when running with
DPDK version < 18.05, but those reached EOL already and their support
is removed from SPDK later within this series.
It would be nice to wait for this VFIO notification inside lib/env_dpdk
e.g. inside the detach function, but we don't know there why the
detach is happening. It could be triggered by a user RPC, not physical
device hotremoval.
Change-Id: I2727de923bb2e3e05a83202465330a32a77d7cfc
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/1732
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
64c4fafd32