[PATCH 29/40] bootlinux: fix kernel_release_file.stat undefined error in update-grub

[Luis Chamberlain <mcgrof@kernel.org>]

The update-grub/install.yml playbook was failing with:
  "The conditional check 'kernel_release_file.stat.exists' failed.
   The error was: 'dict object' has no attribute 'stat'"

This regression was introduced when the update-grub tasks were hardened.
The hardening added multiple instances of checking kernel_release_file.stat.exists
throughout the playbook, but these checks assumed that the stat task would
always run and populate the kernel_release_file variable with a stat attribute.

However, when certain conditions aren't met (e.g., when using pre-built
packages or when the kernel hasn't been built yet), the stat task itself
might be skipped or fail, leaving kernel_release_file without the expected
stat attribute. The hardening didn't account for this possibility, causing
the playbook to fail when trying to access .stat on an incomplete variable
structure.

This commit adds:
1. Defensive checks for kernel_release_file and its stat attribute
   before accessing .exists
2. A default kernelrelease value of "unknown" when it can't be determined
3. Additional checks to ensure kernelrelease is defined and not "unknown"
   before using it in grep commands

These changes prevent the playbook from failing when the kernel
release file doesn't exist or can't be read, allowing it to
gracefully skip the grub default kernel setting steps.

Fixes: fa805e807fad ("bootlinux: Harden update-grub/install.yml")
Generated-by: Claude AI
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 .../bootlinux/tasks/update-grub/install.yml      | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/playbooks/roles/bootlinux/tasks/update-grub/install.yml b/playbooks/roles/bootlinux/tasks/update-grub/install.yml
index 38ec8c76..a10064ee 100644
--- a/playbooks/roles/bootlinux/tasks/update-grub/install.yml
+++ b/playbooks/roles/bootlinux/tasks/update-grub/install.yml
@@ -117,6 +117,12 @@
   when:
     - kernel_release_file.stat.exists
 
+- name: Set default kernelrelease if not determined
+  ansible.builtin.set_fact:
+    kernelrelease: "unknown"
+  when:
+    - kernelrelease is not defined
+
 - name: Get the kernel release of the kernel to be installed
   tags:
     - vars
@@ -134,7 +140,11 @@
       /boot/grub/grub.cfg | awk '{print NR-1" ... "$0}' |
       grep {{ kernelrelease }} | head -1 | awk '{print $1}'
   when:
+    - kernel_release_file is defined
+    - kernel_release_file.stat is defined
     - kernel_release_file.stat.exists
+    - kernelrelease is defined
+    - kernelrelease != "unknown"
     - ansible_os_family != "RedHat" or ansible_distribution_major_version | int < 8
 
 - name: Construct the command line to determine default boot entry for RHEL >= 8
@@ -146,7 +156,11 @@
       cat $f;
       done | grep title | awk '{ gsub("title ", "", $0); print }' | grep '{{ kernelrelease }}';
   when:
+    - kernel_release_file is defined
+    - kernel_release_file.stat is defined
     - kernel_release_file.stat.exists
+    - kernelrelease is defined
+    - kernelrelease != "unknown"
     - ansible_os_family == "RedHat"
     - ansible_distribution_major_version | int >= 8
 
@@ -166,6 +180,8 @@
   register: grub_boot_number_cmd
   changed_when: false
   when:
+    - kernel_release_file is defined
+    - kernel_release_file.stat is defined
     - kernel_release_file.stat.exists
 
 - name: Obtain command to set default kernel to boot
-- 
2.47.2