Drm: mount debugfs before reading dri node in verify_dri_node

[pdostal]

Description

verify_dri_node reads /sys/kernel/debug/dri/*/name directly with no check that debugfs is mounted. On images where it isn't auto-mounted, this fails with AssertionError: cat: '/sys/kernel/debug/dri/*/name': No such file or directory even though hyperv_drm is loaded and working correctly (verify_connection_status, which checks the same driver via modetest instead of debugfs, passes on the same node).

Adds _ensure_debugfs_mounted, mirroring the existing pattern already used in microsoft/testsuites/hyperv/dynamic_memory.py, and calls it before the debugfs read in verify_dri_node.

Type of Change

• Bug fix

Checklist

• Description is filled in above
• No credentials, secrets, or internal details are included
• Peer review requested
• Tests executed and results posted below

Test Results

Image	VM Size	Result

[Copilot]

Pull request overview

This PR fixes verify_dri_node failures on images where debugfs isn’t auto-mounted by ensuring debugfs is mounted before reading /sys/kernel/debug/dri/*/name.

Changes:

• Add _ensure_debugfs_mounted() helper to mount debugfs when needed.
• Call _ensure_debugfs_mounted() at the start of verify_dri_node to avoid missing-path failures.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (1)

lisa/microsoft/testsuites/display/drm.py:139

• Mount.get_partition_info() only parses mount entries that look like /dev/<name> on <mountpoint> ... (see lisa/tools/mount.py), so it won’t report pseudo-filesystem mounts like debugfs on /sys/kernel/debug type debugfs .... As a result, _is_debugfs_mounted() will always return False, causing an unnecessary (and retrying) mount attempt and potentially skipping the test even when debugfs is already mounted.

        def _is_debugfs_mounted() -> bool:
            return any(
                partition.type == FileSystem.debugfs.name
                for partition in mount_tool.get_partition_info(
                    mountpoint=debugfs_point

[LiliDeng]

@pdostal thanks for fixing this, please take care of the CI check error.

./lisa/microsoft/testsuites/display/drm.py:136:64: BLK100 Black would make changes.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (1)

lisa/microsoft/testsuites/display/drm.py:137

• Major: _is_debugfs_mounted() relies on Mount.get_partition_info(mountpoint=...), but get_partition_info() only parses mount lines that start with /dev/... (see lisa/tools/mount.py regex), so it won’t detect debugfs on /sys/kernel/debug type debugfs .... This makes _is_debugfs_mounted() always return False, causing an unnecessary mount attempt and potentially skipping the test even when debugfs is already mounted. Consider parsing mount output for the mountpoint/type instead.

        def _is_debugfs_mounted() -> bool:
            return any(
                partition.type == FileSystem.debugfs.name
                for partition in mount_tool.get_partition_info(mountpoint=debugfs_point)
            )