[PATCH v3 00/17] Hyper-V: add tracing to VMBus module and trace messages/events

[Vitaly Kuznetsov]

Changes since v2:
- Use DEFINE_EVENT in PATCH1/2 to avoid compile warnings [Stephen Hemminger]
- Add PATCH17 tracing channel events [Stephen Hemminger]

Messages between guest and host are used in Hyper-V as control flow. To
simplify debugging various issues which are often hard to reproduce add
tracepoints to all message senders and handlers. This is not a performance
critical path and tracing overhead should be negligible.

The example usage and output is:

Enable all tracing events:
# echo 1 > /sys/kernel/debug/tracing/events/hyperv/enable 

Do something which causes messages to be sent between host and guest, e.g.
hot remove a VMBus device.

Check events:
# cat /sys/kernel/debug/tracing/trace 

# tracer: nop
#
#                              _-----=> irqs-off
#                             / _----=> need-resched
#                            | / _---=> hardirq/softirq
#                            || / _--=> preempt-depth
#                            ||| /     delay
#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
#              | |       |   ||||       |         |
          <idle>-0     [011] ..s.   122.981583: vmbus_on_msg_dpc: msgtype=1
    kworker/11:7-1506  [011] ....   122.981597: vmbus_on_message: msgtype=1
    kworker/11:7-1506  [011] ....   122.981598: vmbus_onoffer: child_relid 0x10, monitorid 0x2, is_dedicated 1, connection_id 0x10010, if_type f8615163-df3e-46c5-913f-f2d2f965ed0e, if_instance 6676e078-e4b3-44da-8a7d-12eafb577d31, chn_flags 0x0, mmio_megabytes 0, sub_channel_index 0
    kworker/11:7-1506  [011] ....   122.982130: vmbus_establish_gpadl_header: sending child_relid 0x10, gpadl 0xe1e34, range_buflen 2056 rangecount 1, ret 0
    kworker/11:7-1506  [011] ....   122.982133: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982136: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982137: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982139: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982141: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982142: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982144: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982146: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
    kworker/11:7-1506  [011] ....   122.982148: vmbus_establish_gpadl_body: sending msgnumber 0, gpadl 0xe1e34, ret 0
          <idle>-0     [011] ..s.   122.982336: vmbus_on_msg_dpc: msgtype=10
          <idle>-0     [011] ..s.   122.982337: vmbus_ongpadl_created: child_relid 0x10, gpadl 0xe1e34, creation_status 0
    kworker/11:7-1506  [011] ....   122.982351: vmbus_open: sending child_relid 0x10, openid 16, gpadlhandle 0xe1e34, target_vp 0xb, offset 0x80, ret 0
     kworker/3:1-214   [003] ....   123.015007: vmbus_setevent: relid 0x5
          <idle>-0     [011] ..s.   123.029467: vmbus_on_msg_dpc: msgtype=6
          <idle>-0     [011] ..s.   123.029470: vmbus_onopen_result: child_relid 0x10, openid 16, status 0
    kworker/11:7-1506  [011] ....   123.029492: vmbus_setevent: relid 0x10
          <idle>-0     [011] d.h.   123.029533: vmbus_chan_sched: relid 0x10
    kworker/11:7-1506  [011] ....   123.029539: vmbus_setevent: relid 0x10

CHANNELMSG_UNLOAD/CHANNELMSG_UNLOAD_RESPONSE are not traced as these are
mostly used on crash.

Vitaly Kuznetsov (17):
  hyper-v: trace vmbus_on_msg_dpc()
  hyper-v: trace vmbus_on_message()
  hyper-v: trace vmbus_onoffer()
  hyper-v: trace vmbus_onoffer_rescind()
  hyper-v: trace vmbus_onopen_result()
  hyper-v: trace vmbus_ongpadl_created()
  hyper-v: trace vmbus_ongpadl_torndown()
  hyper-v: trace vmbus_onversion_response()
  hyper-v: trace vmbus_request_offers()
  hyper-v: trace vmbus_open()
  hyper-v: trace vmbus_close_internal()
  hyper-v: trace vmbus_establish_gpadl()
  hyper-v: trace vmbus_teardown_gpadl()
  hyper-v: trace vmbus_negotiate_version()
  hyper-v: trace vmbus_release_relid()
  hyper-v: trace vmbus_send_tl_connect_request()
  hyper-v: trace channel events

 drivers/hv/Makefile       |   4 +-
 drivers/hv/channel.c      |  21 ++-
 drivers/hv/channel_mgmt.c |  26 +++-
 drivers/hv/connection.c   |   5 +
 drivers/hv/hv_trace.c     |   4 +
 drivers/hv/hv_trace.h     | 327 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/hv/hyperv_vmbus.h |   2 +
 drivers/hv/vmbus_drv.c    |   4 +
 8 files changed, 388 insertions(+), 5 deletions(-)
 create mode 100644 drivers/hv/hv_trace.c
 create mode 100644 drivers/hv/hv_trace.h

-- 
2.13.6