RE: [PATCH RFCv2 00/21] Drivers: hv: utils: re-implement the kernel/userspace communication layer

From: KY Srinivasan
Date: Wed Apr 08 2015 - 12:15:17 EST



> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx]
> Sent: Wednesday, April 8, 2015 9:01 AM
> To: KY Srinivasan
> Cc: devel@xxxxxxxxxxxxxxxxxxxxxx; Haiyang Zhang; linux-
> kernel@xxxxxxxxxxxxxxx; Dexuan Cui; Radim Krcmar; Greg Kroah-Hartman;
> linux-api@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH RFCv2 00/21] Drivers: hv: utils: re-implement the
> kernel/userspace communication layer
>
> KY Srinivasan <kys@xxxxxxxxxxxxx> writes:
>
> >> -----Original Message-----
> >> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx]
> >> Sent: Wednesday, March 11, 2015 6:29 AM
> >> To: KY Srinivasan; devel@xxxxxxxxxxxxxxxxxxxxxx
> >> Cc: Haiyang Zhang; linux-kernel@xxxxxxxxxxxxxxx; Dexuan Cui; Radim
> Krcmar;
> >> Greg Kroah-Hartman; linux-api@xxxxxxxxxxxxxxx
> >> Subject: [PATCH RFCv2 00/21] Drivers: hv: utils: re-implement the
> >> kernel/userspace communication layer
> >>
> >> Changes in RFCv2:
> >> - Preserve backwards compatibility with netlink-speaking daemons. [K. Y.
> >> Srinivasan]
> >> - Introduce transport abstraction layer. [K. Y. Srinivasan]
> >> - Get rid of ioctls [Radim Krcmar]
> >> - Make the series reviewable by splitting it into smaller patches.
> >>
> >> Anatomy of the series:
> >> Patches 01 - 07 are cleanup with minor functional change.
> >> Patch 08 defines the state machine.
> >> Patches 09-11 convert all 3 drivers to using the state machine.
> >> Patch 12 fixes a bug in fcopy. This change is going away in Patch 15, I just
> >> want to highlight the fix.
> >> Patch 13 introduces a transport abstraction.
> >> Patch 14-16 convert all drivers to using the transport abstraction.
> >> Patches 17-18 switch KVP and VSS daemon to using char devices.
> >> Patches 19-20 convert FCOPY and VSS to hull handshake (the same we
> have
> >> in KVP). These two can be postponed till we really need to distinguish
> >> between different kernels in the daemon code.
> >> Patch 21 unifies log messages on daemons connect across all drivers and
> >> moves these messages to debug level.
> >>
> >> I smoke-tested this series with both old (netlink) and new (char devices)
> >> daemons and tested the daemon upgrade procedure.
> >>
> >> Original description:
> >> This series converts kvp/vss daemons to use misc char devices instead of
> >> netlink for userspace/kernel communication and then updates fcopy to
> be
> >> consistent with kvp/vss.
> >>
> >> Userspace/kernel communication via netlink has a number of issues:
> >> - It is hard for userspace to figure out if the kernel part was loaded or not
> >> and this fact can change as there is a way to enable/disable the service
> from
> >> host side. Racy daemon startup is also a problem.
> >> - When the userspace daemon restarts/dies kernel part doesn't receive a
> >> notification.
> >> - Netlink communication is not stable under heavy load.
> >> - ...
> >>
> >> Vitaly Kuznetsov (21):
> >> Drivers: hv: util: move kvp/vss function declarations to
> >> hyperv_vmbus.h
> >> Drivers: hv: kvp: reset kvp_context
> >> Drivers: hv: kvp: move poll_channel() to hyperv_vmbus.h
> >> Drivers: hv: fcopy: process deferred messages when we complete the
> >> transaction
> >> Drivers: hv: vss: process deferred messages when we complete the
> >> transaction
> >> Drivers: hv: kvp: rename kvp_work -> kvp_timeout_work
> >> Drivers: hv: fcopy: rename fcopy_work -> fcopy_timeout_work
> >> Drivers: hv: util: introduce state machine for util drivers
> >> Drivers: hv: kvp: switch to using the hvutil_device_state state
> >> machine
> >> Drivers: hv: vss: switch to using the hvutil_device_state state
> >> machine
> >> Drivers: hv: fcopy: switch to using the hvutil_device_state state
> >> machine
> >> Drivers: hv: fcopy: set .owner reference for file operations
> >> Drivers: hv: util: introduce hv_utils_transport abstraction
> >> Drivers: hv: vss: convert to hv_utils_transport
> >> Drivers: hv: fcopy: convert to hv_utils_transport
> >> Drivers: hv: kvp: convert to hv_utils_transport
> >> Tools: hv: kvp: use misc char device to communicate with kernel
> >> Tools: hv: vss: use misc char device to communicate with kernel
> >> Drivers: hv: vss: full handshake support
> >> Drivers: hv: fcopy: full handshake support
> >> Drivers: hv: utils: unify driver registration reporting
> >>
> >> drivers/hv/Makefile | 2 +-
> >> drivers/hv/hv_fcopy.c | 287 ++++++++++++++--------------------------
> >> drivers/hv/hv_kvp.c | 192 +++++++++++++--------------
> >> drivers/hv/hv_snapshot.c | 168 +++++++++++++++--------
> >> drivers/hv/hv_utils_transport.c | 276
> >> ++++++++++++++++++++++++++++++++++++++
> >> drivers/hv/hv_utils_transport.h | 51 +++++++
> >> drivers/hv/hyperv_vmbus.h | 29 ++++
> >> include/linux/hyperv.h | 8 --
> >> include/uapi/linux/hyperv.h | 8 +-
> >> tools/hv/hv_fcopy_daemon.c | 15 +++
> >> tools/hv/hv_kvp_daemon.c | 166 +++++------------------
> >> tools/hv/hv_vss_daemon.c | 149 ++++++---------------
> >> 12 files changed, 752 insertions(+), 599 deletions(-) create mode 100644
> >> drivers/hv/hv_utils_transport.c create mode 100644
> >> drivers/hv/hv_utils_transport.h
> >
> > Vitaly,
> >
> > Thank you very much for taking on this project; very well done. I have
> mostly reviewed the code and I should be
> > done shortly. Also, I am going to test this code as well. If there are no
> issues, I will send this out to Greg in my next
> > installment of patches.
>
> Hi K.Y.,
>
> I don't mean to rush or anything but please let me know if I need to do
> something with this series (e.g. fix something, rebase/resend it,...) to
> get it applied.

Sorry for the delay Vitaly. I finally was able to test it; please resend the patch-set that can apply on the current tip.

Regards,

K. Y
>
> Thanks,
>
> --
> Vitaly
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