On 11/18/19 10:26 PM, Eric Blake wrote:
On 11/18/19 3:04 PM, Philippe Mathieu-Daudé wrote:
Since not all trace backends support dynamic field width in
format (dtrace via stap does not), forbid them.
Add a check to refuse field width in new formats:
$ make
[...]
GEN hw/block/trace.h
Traceback (most recent call last):
File "scripts/tracetool.py", line 152, in <module>
main(sys.argv)
File "scripts/tracetool.py", line 143, in main
events.extend(tracetool.read_events(fh, arg))
File "scripts/tracetool/__init__.py", line 371, in read_events
event = Event.build(line)
File "scripts/tracetool/__init__.py", line 285, in build
raise ValueError("Event format must not contain field width '%*'")
ValueError: Error at hw/block/trace-events:11: Event format must
not contain field width '%*'
Reported-by: Eric Blake <ebl...@redhat.com>
Buglink: https://bugs.launchpad.net/qemu/+bug/1844817
Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
---
+++ b/docs/devel/tracing.txt
@@ -113,7 +113,8 @@ Format strings should reflect the types defined in
the trace event. Take
special care to use PRId64 and PRIu64 for int64_t and uint64_t types,
respectively. This ensures portability between 32- and 64-bit
platforms.
Format strings must not end with a newline character. It is the
responsibility
-of backends to adapt line ending for proper logging.
+of backends to adapt line ending for proper logging. Format strings
must not
+use numeric field width dynamic precision (SystemTap does not support
them).
Reads awkwardly - a dynamic precision is not numeric in the format
string (but '*' instead). Better might be:
Format strings must not use dynamic field width or precision ('*'), as
at least SystemTap does not support them.
Or even:
Format strings may use numeric field width or precision, but must not
use dynamic forms ('*') as at least SystemTap does not support that.
Each event declaration will start with the event name, then its
arguments,
finally a format string for pretty-printing. For example:
diff --git a/scripts/tracetool/__init__.py
b/scripts/tracetool/__init__.py
index 44c118bc2a..ec7fe9fa4a 100644
--- a/scripts/tracetool/__init__.py
+++ b/scripts/tracetool/__init__.py
@@ -206,6 +206,7 @@ class Event(object):
"\s*"
"(?:(?:(?P<fmt_trans>\".+),)?\s*(?P<fmt>\".+))?"
"\s*")
+ _DFWRE = re.compile(r"%[\d\.\- +#']*\*") # dynamic width precision
The comment is slightly off - this catches both dynamic field width (any
'*' before '.') and dynamic precision (any '*' after '.'), maybe the fix
is just s/width/width or/
_VALID_PROPS = set(["disable", "tcg", "tcg-trans", "tcg-exec",
"vcpu"])
@@ -280,6 +281,8 @@ class Event(object):
if fmt.endswith(r'\n"'):
raise ValueError("Event format must not end with a
newline "
"character")
+ if Event._DFWRE.search(fmt):
+ raise ValueError("Event format must not contain field
width '%*'")
and I don't know if you want to tweak the error message, maybe:
Event format must not use dynamic '*'
If we're trying to get stuff in 4.2-rc2, patch 1 and 2 are actual bug
fixes and deserve to go in; patch 3 is nice-to-have but doesn't affect
the build if it is omitted (as there are no other offenders left), so
slipping it into 5.0 for a v4 to clean it up slightly doesn't hurt. I
don't know who would send the pull request, though, and slipping 1 and 2
into -rc3 just because of 3 is not ideal.
Wise thought. I'll respin 1-2 with the Fixes: tag in case qemu-block@ or
qemu-trivial@ have pending pull-request for tomorrow, they can queue it.
Else they can go via the mips-next tree, since both patch affect the
Malta board.
Thanks!
Phil.
