[1.1] libct: fix a race with systemd removal #3877
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For a previous attempt to fix that (and added test cases), see commit 9087f2e. Alas, it's not always working because of cgroup directory TOCTOU. To solve this and avoid the race, add an error _after_ the operation. Implement it as a method that ignores the error that should be ignored. Instead of currentStatus(), use faster runType(), since we are not interested in Paused status here. For Processes(), remove the pre-op check, and only use it after getting an error, making the non-error path more straightforward. For Signal(), add a second check after getting an error. The first check is left as is because signalAllProcesses might print a warning if the cgroup does not exist, and we'd like to avoid that. This should fix an occasional failure like this one: not ok 84 kill detached busybox # (in test file tests/integration/kill.bats, line 27) # `[ "$status" -eq 0 ]' failed .... # runc kill test_busybox KILL (status=0): # runc kill -a test_busybox 0 (status=1): # time="2023-04-04T18:24:27Z" level=error msg="lstat /sys/fs/cgroup/devices/system.slice/runc-test_busybox.scope: no such file or directory" (cherry picked from commit fe278b9) Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
AkihiroSuda
approved these changes
May 24, 2023
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This is a backport of #3812 to release-1.1 branch. Original description follows.
For a previous attempt to fix that (and added test cases), see commit 9087f2e.
Alas, it's not always working because of cgroup directory TOCTOU.
To solve this and avoid the race, add an error after the operation. Implement it as a method that ignores the error that should be ignored. Instead of currentStatus(), use faster runType(), since we are not interested in Paused status here.
For Processes(), remove the pre-op check, and only use it after getting an error, making the non-error path more straightforward.
For Signal(), add a second check after getting an error. The first check is left as is because signalAllProcesses might print a warning if the cgroup does not exist, and we'd like to avoid that.
This should fix an occasional failure like this one:
(cherry picked from commit fe278b9)