firstlogin: replace session kill with flock

[enthropy7]

Fixes #9032.

On a fresh image root is logged in on tty1, on the serial console and over ssh at the same time, and every one of those sessions runs armbian-firstlogin. Each one killed the other root shells so it could have the prompts to itself, so a session sitting at a password prompt gets SIGKILLed and the setup is left unfinished with the marker still in place. From the surviving session it looks like the login hangs. This takes /run/armbian-firstlogin.lock instead: the first session runs the setup, the others print one line and exit. The kill block is then unnecessary and removed, along with its habit of killing unrelated root shells that happen to end in sh. Flock comes from util-linux, which is Essential, so it is always present.

that was catched up and fixed, also reproduced and tested. i think this should be merged, i couldn't imagine more idiomatic solution to this.

Board: Orange Pi Zero (Allwinner H3, 4× Cortex-A7), Armbian community 26.11 trunk, Debian trixie, kernel 6.18.44-current-sunxi.

setup mirrors the preset from the report:

# /root/.not_logged_in_yet
PRESET_ROOT_PASSWORD="123"

with a preset password the script skips the prompt and goes straight to the kill block, which makes the race deterministic. two root logins over ssh, started at the same moment.

before (current main) - first run, both sessions killed:

systemd[1]: Started session-15.scope - Session 15 of User root.
systemd[1]: Started session-16.scope - Session 16 of User root.
systemd[1]: session-16.scope: Deactivated successfully.
systemd[1]: session-15.scope: Deactivated successfully.

second run, one session killed 7 s in, its transcript cut mid-banner:

[  0.0s] A: spawned
[  0.0s] B: spawned
[  7.0s] B: PTY CLOSED   (ssh rc=255)


Waiting for system to finish booting ...
Welcome to Armbian_community!
Documentation: https://docs.armbian.com | Community su     <-- cut

after (this PR):

A: alive=True steppedaside=False shell_responded=False <- owns the setup
B: alive=True steppedaside=True shell_responded=True

B printed First login setup is already running in another session., dropped to a normal shell and answered a command; A kept the prompts. Nothing was killed.

Summary by CodeRabbit

• Bug Fixes
  • Prevented multiple first-login setup sessions from running simultaneously.
  • Setup now exits gracefully when another session is already active.
  • Removed behavior that could forcibly terminate other root shell sessions.

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📝 Walkthrough

Walkthrough

First-login now uses a nonblocking runtime lock to prevent concurrent setup sessions. It no longer scans for or force-kills other root shell sessions.

Changes

First-login session control

Layer / File(s)	Summary
Lock first-login sessions packages/bsp/common/usr/lib/armbian/armbian-firstlogin	The script acquires a nonblocking runtime lock and exits when another setup session holds it. The process scan and kill -9 logic were removed.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 66165

The change replaces competing first-login session termination with a lock so one session performs setup while others exit safely; no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: mingzhangqun, mkiring, igorpecovnik

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes address issue #9032 by preventing concurrent setup sessions and removing the ps|awk|kill race.
Out of Scope Changes check	✅ Passed	The changes are limited to replacing root-session termination with locking in armbian-firstlogin.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: replacing session termination with flock-based locking.

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Inline comments:
In `@packages/bsp/common/usr/lib/armbian/armbian-firstlogin`:
- Around line 791-794: Update the lock setup around flock so failure to open the
lock file via exec 9 is detected and returns a nonzero status before invoking
flock. Preserve the existing successful lock acquisition and lock-contention
message/exit behavior.

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[enthropy7]

addressed the review. a failed exec 9> … no longer falls through into the contention branch. Bash does not abort on a redirection error here, so flock would fail with Bad file descriptor and the script would report "already running in another session" and exit 0.

verified on my board by making the lock path a directory. without the guard it printed that message and exited 0, with the guard it reports Is a directory and exits nonzero, leaving the marker in place so the setup runs again on the next login

[igorpecovnik]

thank you

[github-actions]

✅ This PR has been reviewed and approved — all set for merge!

[enthropy7]

merged main into my fork. everything still the same, no changes in the code