fix server session unbound error

[hholoubk]

Initialize server_session to None at function start to prevent
UnboundLocalError when referenced in finally block. The variable
was previously only defined within a conditional block, causing
an error when the condition was not met.

Summary by CodeRabbit

Release Notes

• New Features

  • Added support for HTX stress tool testing within virtual machines, including automated installation and execution.
  • Extended stress testing options with new "htxcmdline_in_vms" variant for VM-specific stress execution.

• Bug Fixes

  • Fixed variable initialization in remote log retrieval logic to prevent undefined reference errors.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

The changes introduce HTX stress tool support and improve code robustness across two files. In virttest/utils_sys.py, a server_session variable is initialized to None before the try block in get_qemu_log to prevent undefined variable errors in the finally block. In virttest/utils_test/__init__.py, a new load_htxstress_tool method is added to manage HTX tool installation and execution in VMs. The stress loading flow is extended to recognize the "htxcmdline_in_vms" stress type. Additionally, stress type normalization is implemented in Stress.__init__ and VMStress.__init__, and multiple regex patterns are converted to raw strings for consistency and correctness.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Pre-merge checks

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix server session unbound error' is directly related to the primary fix described in the PR objectives, addressing the UnboundLocalError in the get_qemu_log function. However, the PR also contains a significant secondary change adding htx stress tool support, which is not reflected in the title.
Docstring Coverage	✅ Passed	Docstring coverage is 83.33% which is sufficient. The required threshold is 80.00%.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 2

📜 Review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 363ce48 and 2bb3117.

📒 Files selected for processing (2)

• virttest/utils_sys.py
• virttest/utils_test/__init__.py

🧰 Additional context used

🪛 GitHub Actions: pre-commit

virttest/utils_test/__init__.py

[error] 1-1: pre-commit hook 'black' reformatted virttest/utils_test/init.py and exited with code 1. Command: 'pre-commit run --show-diff-on-failure --color=always --all-files'. Re-run to apply formatting changes.

🪛 Ruff (0.14.10)

virttest/utils_test/__init__.py

2418-2418: Avoid specifying long messages outside the exception class

(TRY003)

---

2442-2442: Avoid specifying long messages outside the exception class

(TRY003)

🔇 Additional comments (6)

virttest/utils_sys.py (1)

150-150: LGTM!

This correctly prevents the UnboundLocalError by ensuring server_session is always defined before the try block. The finally block's check if server_session: will safely evaluate to False when server_session is None, preventing both the error and unnecessary close attempts.

virttest/utils_test/__init__.py (5)

483-486: LGTM!

Converting these regex patterns to raw strings is the correct approach to avoid potential issues with backslash escape sequences.

---

876-876: LGTM!

Raw string usage for regex patterns is appropriate.

Also applies to: 896-896

---

1507-1510: LGTM!

Raw string conversions for regex patterns are correct and consistent.

Also applies to: 2066-2066, 2083-2083

---

2834-2877: Logic looks correct, but verify integration with load_htxstress_tool.

The per-VM stress type customization and the branching logic for HTX are correctly implemented. The code appropriately preserves the original stress_type in default_stress_type before the loop modifications.

However, the reliability of this code path depends on fixing the error handling issues in load_htxstress_tool mentioned above.

---

2682-2683: LGTM!

The per-VM stress type configuration allows flexibility in running different stress tools on different VMs. The value is properly passed to the parent class where normalization occurs.

[coderabbitai]

⚠️ Potential issue | 🟡 Minor

Pipeline failure: Black formatting required.

The pre-commit hook indicates this file needs reformatting. The single quotes here may need to be double quotes for consistency with the codebase style.

-        stress_type = stress_type.split('_')[0]
+        stress_type = stress_type.split("_")[0]

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	stress_type = stress_type.split('_')[0]
	stress_type = stress_type.split("_")[0]

🤖 Prompt for AI Agents

In virttest/utils_test/__init__.py around line 2330, the string literal uses
single quotes which fails the project's Black/formatting/pre-commit checks;
replace single quotes with double quotes for that literal (change 'stress_type'
usage to use double-quoted string) and re-run Black or pre-commit formatting to
ensure the file is properly reformatted.

[coderabbitai]

⚠️ Potential issue | 🟠 Major

Missing error handling for critical installation steps.

The wget and package installation commands are executed without checking their return status. Since self.cmd uses ignore_status=True / ignore_all_errors=True, failures will be silently ignored. If the download or installation fails, the function will proceed to start a stress tool that wasn't installed, resulting in a confusing failure later.

🔎 Proposed fix with error handling

         LOG.info("Installing htx rpm/deb in the guest")
-        self.cmd(remove_old_package)
-        self.cmd(get_stress)
-        self.cmd(install_stress)
+        self.cmd(remove_old_package)
+        
+        status, output = self.cmd_status_output(get_stress, timeout=self.stress_shell_timeout)
+        if status != 0:
+            raise exceptions.TestError("Failed to download HTX stress tool: %s" % output)
+        
+        status, output = self.cmd_status_output(install_stress, timeout=self.stress_shell_timeout)
+        if status != 0:
+            raise exceptions.TestError("Failed to install HTX stress tool: %s" % output)

Committable suggestion skipped: line range outside the PR's diff.