[PATCH V4 3/3] tools/perf: Fix parallel-perf python script to replace new python syntax ":=" usage

Athira Rajeev
2024-06-23T06:49:19Z

perf test "perf script tests" fails as below in systems
with python 3.6

File "/home/athira/linux/tools/perf/tests/shell/../../scripts/python/parallel-perf.py", line 442
if line := p.stdout.readline():
^
SyntaxError: invalid syntax
--- Cleaning up ---
---- end(-1) ----
92: perf script tests: FAILED!

This happens because ":=" is a new syntax that assigns values
to variables as part of a larger expression. This is introduced
from python 3.8 and hence fails in setup with python 3.6
Address this by splitting the large expression and check the
value in two steps:
Previous line: if line := p.stdout.readline():
Current change:
line = p.stdout.readline()
if line:

With patch

./perf test "perf script tests"
93: perf script tests: Ok

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
---
Changelog:
v1 -> v2
Added "Acked-by" from Adrian

tools/perf/scripts/python/parallel-perf.py | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/scripts/python/parallel-perf.py b/tools/perf/scripts/python/parallel-perf.py
index 21f32ec5ed46..be85fd7f6632 100755
--- a/tools/perf/scripts/python/parallel-perf.py
+++ b/tools/perf/scripts/python/parallel-perf.py
@@ -439,7 +439,8 @@ def ProcessCommandOutputLines(cmd, per_cpu, fn, *x):
pat = re.compile(r"\s*\[[0-9]+\]")
p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
while True:
- if line := p.stdout.readline():
+ line = p.stdout.readline()
+ if line:
line = line.decode("utf-8")
if pat.match(line):
line = line.split()
--
2.35.3