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tools/ustat: Properly handle SIGINT in ustat #5498

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tools/ustat: Properly handle SIGINT in ustat #5498

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9 changes: 9 additions & 0 deletions tools/lib/ustat.py
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
import sys
from subprocess import call
from time import sleep, strftime
import signal

class Category(object):
THREAD = "THREAD"
Expand Down Expand Up @@ -242,10 +243,17 @@ def _detach_probes(self):
self.bpf.cleanup() # Cleans up all attached probes
self.bpf = None

def _sigint_handler(self, signum, frame):
self.exiting = True;
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Copilot AI Apr 26, 2026

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self.exiting = True; ends with a semicolon, which triggers pycodestyle E703 (and scripts/py-style-check.sh runs pycodestyle over tools/**/*.py). Remove the trailing semicolon to avoid CI/style check failures.

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self.exiting = True;
self.exiting = True

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if self.in_sleep:
raise KeyboardInterrupt
Comment on lines +246 to +249
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Copilot AI Apr 26, 2026

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_sigint_handler reads self.in_sleep, but in_sleep is only set inside _loop_iter. If SIGINT arrives before the first iteration (or between iterations), this will raise AttributeError from inside the signal handler. Initialize self.in_sleep = False before installing the handler (e.g., in run()), or use getattr(self, 'in_sleep', False) in the handler.

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def _loop_iter(self):
self._attach_probes()
try:
self.in_sleep = True
sleep(self.args.interval)
self.in_sleep = False
Comment on lines 251 to +256
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Copilot AI Apr 26, 2026

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With the custom SIGINT handler, SIGINT received outside the sleep() window (e.g., during _attach_probes() or printing) sets self.exiting = True but _loop_iter() will still call sleep(self.args.interval) on that iteration. Consider checking self.exiting before sleeping so Ctrl-C exits promptly when possible (while still allowing cleanup to run).

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except KeyboardInterrupt:
self.exiting = True
Comment on lines +256 to 258
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If sleep() is interrupted, execution jumps to the except KeyboardInterrupt block and self.in_sleep stays True. That can cause later SIGINTs (e.g., during detach/cleanup) to incorrectly raise KeyboardInterrupt, reintroducing the cleanup failure this PR is trying to avoid. Ensure self.in_sleep is always reset (e.g., move it into a finally block).

Suggested change
self.in_sleep = False
except KeyboardInterrupt:
self.exiting = True
except KeyboardInterrupt:
self.exiting = True
finally:
self.in_sleep = False

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Expand Down Expand Up @@ -293,6 +301,7 @@ def run(self):
self.args.interval)
countdown = self.args.count
self.exiting = False
signal.signal(signal.SIGINT, self._sigint_handler)
while True:
self._loop_iter()
countdown -= 1
Expand Down
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