2020-01-13 06:31:52

by Dexuan Cui

Subject: [PATCH v2 0/4] hv_utils: Add the support of hibernation

Hi,
This is an updated version of the v1 patchset:
https://lkml.org/lkml/2019/9/11/861

Patch #1 is a new patch that makes the daemons more robust.

Patch #2 is the same as v1.

Patch #3 sends the host-initiated hibernation request to the user space via udev.
(v1 used call_usermodehelper() and "/sbin/hyperv-hibernate".)

Patch #4 handles fcopy/vss specially to avoid possible inconsistent states.

Please review.

Thanks!

Dexuan Cui (4):
Patch #1: Tools: hv: Reopen the devices if read() or write() returns errors
Patch #2: hv_utils: Support host-initiated restart request
Patch #3: hv_utils: Support host-initiated hibernation request
Patch #4: hv_utils: Add the support of hibernation

drivers/hv/hv_fcopy.c | 58 +++++++++++++++-
drivers/hv/hv_kvp.c | 44 +++++++++++-
drivers/hv/hv_snapshot.c | 60 ++++++++++++++++-
drivers/hv/hv_util.c | 133 ++++++++++++++++++++++++++++++++++++-
drivers/hv/hyperv_vmbus.h | 6 ++
include/linux/hyperv.h | 2 +
tools/hv/hv_fcopy_daemon.c | 19 ++++--
tools/hv/hv_kvp_daemon.c | 25 ++++---
tools/hv/hv_vss_daemon.c | 25 +++++--
9 files changed, 344 insertions(+), 28 deletions(-)

--
2.19.1

2020-01-13 22:32:39

by Dexuan Cui

Subject: RE: [PATCH v2 0/4] hv_utils: Add the support of hibernation

> From: Dexuan Cui
> Sent: Sunday, January 12, 2020 10:29 PM
>
> Hi,
> This is an updated version of the v1 patchset:
> https://lkml.org/lkml/2019/9/11/861
>
> Patch #1 is a new patch that makes the daemons more robust.
>
> Patch #2 is the same as v1.
>
> Patch #3 sends the host-initiated hibernation request to the user space via
> udev.
> (v1 used call_usermodehelper() and "/sbin/hyperv-hibernate".)
>
> Patch #4 handles fcopy/vss specially to avoid possible inconsistent states.
>
> Please review.
>
> Thanks!
>
> Dexuan Cui (4):
> Patch #1: Tools: hv: Reopen the devices if read() or write() returns errors
> Patch #2: hv_utils: Support host-initiated restart request
> Patch #3: hv_utils: Support host-initiated hibernation request
> Patch #4: hv_utils: Add the support of hibernation

Hi Vitaly,
I forgot to mention this for patch #4: IMO we don't need to add a new
HVUTIL_SUSPENDED state to the hvutil state machine, because:

When we reach util_suspend(), all the userspace processes have been
frozen: see kernel/power/hibernate.c: hibernate() -> freeze_processes() ->
try_to_freeze_tasks(true) -> freeze_task() -> fake_signal_wake_up(). When
try_to_freeze_tasks(true) returns 0, all the user-space processes must be
frozen in do_signal() -> get_signal() -> try_to_freeze() -> ... -> __refrigerator().

hibernate () -> hibernation_snapshot () -> dpm_suspend() -> ... ->
util_suspend() only runs after hibernate() -> freeze_processes(), so I'm
pretty sure we have no race condition with the user space daemon.

util_suspend() -> srv->util_pre_suspend() disables the tasklet and cancels any
pening work items, so there is no race in the kernel space, either.

Thanks,
-- Dexuan