From 99f5303c8b857320b00a63dca81d1f6f7c75c636 Mon Sep 17 00:00:00 2001 From: Alper Nebi Yasak Date: Fri, 4 Jun 2021 22:04:46 +0300 Subject: [PATCH] test/py: Wait for guestmount worker to exit after running guestunmount Some filesystem tests are failing when their image is prepared with guestmount, but succeeding if loop mounts are used instead. The reason seems to be a race condition the guestmount(1) manual page explains: When guestunmount(1)/fusermount(1) exits, guestmount may still be running and cleaning up the mountpoint. The disk image will not be fully finalized. This means that scripts like the following have a nasty race condition: guestmount -a disk.img -i /mnt # copy things into /mnt guestunmount /mnt # immediately try to use 'disk.img' ** UNSAFE ** The solution is to use the --pid-file option to write the guestmount PID to a file, then after guestunmount spin waiting for this PID to exit. The Python standard library has an os.waitpid() function for waiting a child to terminate, but it cannot wait on non-child processes. Implement a utility function that can do this by polling the process repeatedly for a given duration, optionally killing the process if it won't terminate on its own. Apply the suggested solution with this utility function, which makes the failing tests succeed again. Signed-off-by: Alper Nebi Yasak Reviewed-by: Simon Glass --- test/py/tests/test_fs/conftest.py | 13 ++++++++++- test/py/u_boot_utils.py | 36 +++++++++++++++++++++++++++++++ 2 files changed, 48 insertions(+), 1 deletion(-) diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py index 0189298f91..b638284e07 100644 --- a/test/py/tests/test_fs/conftest.py +++ b/test/py/tests/test_fs/conftest.py @@ -8,6 +8,7 @@ import pytest import re from subprocess import call, check_call, check_output, CalledProcessError from fstest_defs import * +import u_boot_utils as util supported_fs_basic = ['fat16', 'fat32', 'ext4'] supported_fs_ext = ['fat16', 'fat32'] @@ -210,7 +211,7 @@ def mount_fs(fs_type, device, mount_point): global fuse_mounted try: - check_call('guestmount -a %s -m /dev/sda %s' + check_call('guestmount --pid-file guestmount.pid -a %s -m /dev/sda %s' % (device, mount_point), shell=True) fuse_mounted = True return @@ -239,6 +240,16 @@ def umount_fs(mount_point): if fuse_mounted: call('sync') call('guestunmount %s' % mount_point, shell=True) + + try: + with open("guestmount.pid", "r") as pidfile: + pid = int(pidfile.read()) + util.waitpid(pid, kill=True) + os.remove("guestmount.pid") + + except FileNotFoundError: + pass + else: call('sudo umount %s' % mount_point, shell=True) diff --git a/test/py/u_boot_utils.py b/test/py/u_boot_utils.py index 939d82eec1..e816c7fbb6 100644 --- a/test/py/u_boot_utils.py +++ b/test/py/u_boot_utils.py @@ -8,6 +8,7 @@ import inspect import os import os.path import pytest +import signal import sys import time import re @@ -339,3 +340,38 @@ def crc32(u_boot_console, address, count): assert m, 'CRC32 operation failed.' return m.group(1) + +def waitpid(pid, timeout=60, kill=False): + """Wait a process to terminate by its PID + + This is an alternative to a os.waitpid(pid, 0) call that works on + processes that aren't children of the python process. + + Args: + pid: PID of a running process. + timeout: Time in seconds to wait. + kill: Whether to forcibly kill the process after timeout. + + Returns: + True, if the process ended on its own. + False, if the process was killed by this function. + + Raises: + TimeoutError, if the process is still running after timeout. + """ + try: + for _ in range(timeout): + os.kill(pid, 0) + time.sleep(1) + + if kill: + os.kill(pid, signal.SIGKILL) + return False + + except ProcessLookupError: + return True + + raise TimeoutError( + "Process with PID {} did not terminate after {} seconds." + .format(pid, timeout) + ) -- 2.39.5