[Qemu-devel] [PATCH 1.1 0/2] tracing: QEMU 1.1-rc3+ fixes

[Qemu-devel] [PATCH 1.1 0/2] tracing: QEMU 1.1-rc3+ fixes

[Stefan Hajnoczi]

Two issues have been reported with the new tracetool Python rewrite:

1. Using parenthesis in ./trace-events format strings produces an exception
   from tracetool.py.

2. The 'simple' trace backend event numbering is wrong when the ./trace-events
   file contains disabled events (this is the case by default).

These patches fix these issues.

Stefan Hajnoczi (2):
  simpletrace: skip disabled trace event numbering
  tracetool: allow parenthesis in trace-events format strings

 scripts/simpletrace.py        |    5 +++--
 scripts/tracetool/__init__.py |    2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

-- 
1.7.10

[Qemu-devel] [PATCH 1.1 1/2] simpletrace: skip disabled trace event numbering

[Stefan Hajnoczi]

The simple trace code generator has been rewritten for QEMU 1.1 and now
assigns event numbers only to enabled events.  This means we must skip
disabled events when pretty-printing traces in simpletrace.py.

Note this means old binary traces may be pretty printed incorrectly
since they use a different event numbering when the "disable" keyword is
present in ./trace-events.  It's unfortunate but not easy to avoid at
this stage.  Always use the simpletrace.py that came with the QEMU
binary to ensure correctly pretty-printing.

Reported-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 scripts/simpletrace.py |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/scripts/simpletrace.py b/scripts/simpletrace.py
index f55e5e6..db39b02 100755
--- a/scripts/simpletrace.py
+++ b/scripts/simpletrace.py
@@ -37,8 +37,9 @@ def parse_events(fobj):
             continue
 
         disable, name, args = m.groups()
-        events[event_num] = (name,) + get_argnames(args)
-        event_num += 1
+        if not disable:
+            events[event_num] = (name,) + get_argnames(args)
+            event_num += 1
     return events
 
 def read_record(fobj):
-- 
1.7.10

[Qemu-devel] [PATCH 1.1 2/2] tracetool: allow parenthesis in trace-events format strings

[Stefan Hajnoczi]

The regular expression used to parse ./trace-events fails on the
following input:

  test_paren(int n) "(%d)"

The problem is that the regular expression uses greedy matching and '"'
becomes the name of the event while 'test_paren(int n) ' becomes the
properties of the event.

Prevent greedy matching from going too far by explicitly saying the name
cannot have a '"'.  This forces the regular expression engine to
backtrack to the desired match.

Reported-by: Bob Breuer <breuerr@mc.net>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 scripts/tracetool/__init__.py |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
index 175df08..148f553 100644
--- a/scripts/tracetool/__init__.py
+++ b/scripts/tracetool/__init__.py
@@ -120,7 +120,7 @@ class Event(object):
         The event arguments.
     """
 
-    _CRE = re.compile("((?P<props>.*)\s+)?(?P<name>[^(\s]+)\((?P<args>[^)]*)\)\s*(?P<fmt>\".*)?")
+    _CRE = re.compile("((?P<props>.*)\s+)?(?P<name>[^\"(\s]+)\((?P<args>[^)]*)\)\s*(?P<fmt>\".*)?")
 
     _VALID_PROPS = set(["disable"])
 
-- 
1.7.10

Re: [Qemu-devel] [PATCH 1.1 2/2] tracetool: allow parenthesis in trace-events format strings

[Lluís Vilanova]

Stefan Hajnoczi writes:

> The regular expression used to parse ./trace-events fails on the
> following input:

>   test_paren(int n) "(%d)"

> The problem is that the regular expression uses greedy matching and '"'
> becomes the name of the event while 'test_paren(int n) ' becomes the
> properties of the event.

> Prevent greedy matching from going too far by explicitly saying the name
> cannot have a '"'.  This forces the regular expression engine to
> backtrack to the desired match.

> Reported-by: Bob Breuer <breuerr@mc.net>
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Reviewed-by: Lluís Vilanova <vilanova@ac.upc.edu>


> ---
>  scripts/tracetool/__init__.py |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

> diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
> index 175df08..148f553 100644
> --- a/scripts/tracetool/__init__.py
> +++ b/scripts/tracetool/__init__.py
> @@ -120,7 +120,7 @@ class Event(object):
>          The event arguments.
>      """
 
> -    _CRE = re.compile("((?P<props>.*)\s+)?(?P<name>[^(\s]+)\((?P<args>[^)]*)\)\s*(?P<fmt>\".*)?")
> +    _CRE = re.compile("((?P<props>.*)\s+)?(?P<name>[^\"(\s]+)\((?P<args>[^)]*)\)\s*(?P<fmt>\".*)?")
 
>      _VALID_PROPS = set(["disable"])
 
> -- 
> 1.7.10


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