kunit: tool: Terminate kernel under test on SIGINT

kunit.py will attempt to catch SIGINT / ^C in order to ensure the TTY isn't
messed up, but never actually attempts to terminate the running kernel (be
it UML or QEMU). This can lead to a bit of frustration if the kernel has
crashed or hung.

Terminate the kernel process in the signal handler, if it's running. This
requires plumbing through the process handle in a few more places (and
having some checks to see if the kernel is still running in places where it
may have already been killed).

Reported-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Closes: https://lore.kernel.org/all/aaFmiAmg9S18EANA@smile.fi.intel.com/
Signed-off-by: David Gow <david@davidgow.net>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Tested-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit_kernel.py

@@ -16,7 +16,7 @@ import shutil
 import signal
 import sys
 import threading
-from typing import Iterator, List, Optional, Tuple
+from typing import Iterator, List, Optional, Tuple, Any
 from types import FrameType
 
 import kunit_config
@@ -265,6 +265,7 @@ class LinuxSourceTree:
 		if kconfig_add:
 			kconfig = kunit_config.parse_from_string('\n'.join(kconfig_add))
 			self._kconfig.merge_in_entries(kconfig)
+		self._process : Optional[subprocess.Popen[Any]] = None
 
 	def arch(self) -> str:
 		return self._arch
@@ -364,36 +365,45 @@ class LinuxSourceTree:
 			args.append('kunit.filter_action=' + filter_action)
 		args.append('kunit.enable=1')
 
-		process = self._ops.start(args, build_dir)
-		assert process.stdout is not None  # tell mypy it's set
+		self._process = self._ops.start(args, build_dir)
+		assert self._process is not None # tell mypy it's set
+		assert self._process.stdout is not None  # tell mypy it's set
 
 		# Enforce the timeout in a background thread.
 		def _wait_proc() -> None:
 			try:
-				process.wait(timeout=timeout)
+				if self._process:
+					self._process.wait(timeout=timeout)
 			except Exception as e:
 				print(e)
-				process.terminate()
-				process.wait()
+				if self._process:
+					self._process.terminate()
+					self._process.wait()
 		waiter = threading.Thread(target=_wait_proc)
 		waiter.start()
 
 		output = open(get_outfile_path(build_dir), 'w')
 		try:
 			# Tee the output to the file and to our caller in real time.
-			for line in process.stdout:
+			for line in self._process.stdout:
 				output.write(line)
 				yield line
 		# This runs even if our caller doesn't consume every line.
 		finally:
 			# Flush any leftover output to the file
-			output.write(process.stdout.read())
+			if self._process:
+				if self._process.stdout:
+					output.write(self._process.stdout.read())
+					self._process.stdout.close()
+				self._process = None
 			output.close()
-			process.stdout.close()
 
 			waiter.join()
 			self._restore_terminal_if_tty()
 
 	def signal_handler(self, unused_sig: int, unused_frame: Optional[FrameType]) -> None:
 		logging.error('Build interruption occurred. Cleaning console.')
+		if self._process:
+				self._process.terminate()
+				self._process.wait()
 		self._restore_terminal_if_tty()