[Qemu-devel] [PULL for-2.9 0/1] Tracing patches

[Qemu-devel] [PULL for-2.9 0/1] Tracing patches

[Stefan Hajnoczi]

The following changes since commit dd1559bb267becbb838de41132ef60771d183e5d:

  Merge remote-tracking branch 'elmarco/tags/chr-tests-pull-request' into staging (2017-05-05 17:07:55 +0100)

are available in the git repository at:

  git://github.com/stefanha/qemu.git tags/tracing-pull-request

for you to fetch changes up to f3fddaf60b9b983b82cd11e8087e7c8a3903ee14:

  trace: disallow more than 10 arguments per trace event (2017-05-08 09:38:30 -0400)

----------------------------------------------------------------

----------------------------------------------------------------

Daniel P. Berrange (1):
  trace: disallow more than 10 arguments per trace event

 scripts/tracetool/__init__.py | 4 ++++
 1 file changed, 4 insertions(+)

-- 
2.9.3

[Qemu-devel] [PULL for-2.9 1/1] trace: disallow more than 10 arguments per trace event

[Stefan Hajnoczi]

From: "Daniel P. Berrange" <berrange@redhat.com>

The UST trace backend can only cope with upto 10 arguments. To ensure we
don't exceed the limit when UST is not compiled in, disallow more than
10 arguments upfront.

This prevents the case where:

  commit 0fc8aec7de64f2bf83a274a2a38b938ce03425d2
  Author: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
  Date:   Tue Apr 18 10:20:20 2017 +0800

    COLO-compare: Optimize tcp compare trace event

    Optimize two trace events as one, adjust print format make
    it easy to read. rename trace_colo_compare_pkt_info_src/dst
    to trace_colo_compare_tcp_info.

regressed the fix done in

  commit 2dfe5113b11ce0ddb08176ebb54ab7ac4104b413
  Author: Alex Bennée <alex.bennee@linaro.org>
  Date:   Fri Oct 28 14:25:59 2016 +0100

    net: split colo_compare_pkt_info into two trace events

    It seems there is a limit to the number of arguments a UST trace event
    can take and at 11 the previous trace command broke the build. Split the
    trace into a src pkt and dst pkt trace to fix this.

    Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
    Message-id: 20161028132559.8324-1-alex.bennee@linaro.org
    Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
    Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Now we get an immediate fail even when UST is disabled:

  GEN     net/trace.h
Traceback (most recent call last):
  File "/home/berrange/src/virt/qemu/scripts/tracetool.py", line 154, in <module>
    main(sys.argv)
  File "/home/berrange/src/virt/qemu/scripts/tracetool.py", line 145, in main
    events.extend(tracetool.read_events(fh))
  File "/home/berrange/src/virt/qemu/scripts/tracetool/__init__.py", line 307, in read_events
    event = Event.build(line)
  File "/home/berrange/src/virt/qemu/scripts/tracetool/__init__.py", line 244, in build
    event = Event(name, props, fmt, args)
  File "/home/berrange/src/virt/qemu/scripts/tracetool/__init__.py", line 196, in __init__
    "argument count" % name)
ValueError: Event 'colo_compare_tcp_info' has more than maximum permitted argument count
Makefile:96: recipe for target 'net/trace.h-timestamp' failed

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20170426153900.21066-1-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 scripts/tracetool/__init__.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
index 365446f..1ffbc1d 100644
--- a/scripts/tracetool/__init__.py
+++ b/scripts/tracetool/__init__.py
@@ -191,6 +191,10 @@ class Event(object):
         self.event_trans = event_trans
         self.event_exec = event_exec
 
+        if len(args) > 10:
+            raise ValueError("Event '%s' has more than maximum permitted "
+                             "argument count" % name)
+
         if orig is None:
             self.original = weakref.ref(self)
         else:
-- 
2.9.3

Re: [Qemu-devel] [PULL for-2.9 0/1] Tracing patches

[Stefan Hajnoczi]

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On Mon, May 08, 2017 at 09:39:07AM -0400, Stefan Hajnoczi wrote:
> The following changes since commit dd1559bb267becbb838de41132ef60771d183e5d:
> 
>   Merge remote-tracking branch 'elmarco/tags/chr-tests-pull-request' into staging (2017-05-05 17:07:55 +0100)
> 
> are available in the git repository at:
> 
>   git://github.com/stefanha/qemu.git tags/tracing-pull-request
> 
> for you to fetch changes up to f3fddaf60b9b983b82cd11e8087e7c8a3903ee14:
> 
>   trace: disallow more than 10 arguments per trace event (2017-05-08 09:38:30 -0400)
> 
> ----------------------------------------------------------------
> 
> ----------------------------------------------------------------
> 
> Daniel P. Berrange (1):
>   trace: disallow more than 10 arguments per trace event
> 
>  scripts/tracetool/__init__.py | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> -- 
> 2.9.3
> 
> 

Thanks, applied to my staging tree:
https://github.com/stefanha/qemu/commits/staging

Stefan

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