kdump-tools: Cope with the lack of initramfs-tools OPTION=VAR feature in Debian

Currently, there's an interesting feature on Ubuntu's initramfs-tools
that allows a fine-tuned control on the hooks/scripts that will be
executed/included in the initrd image, depending on options set on
initramfs-tools.conf and validated via OPTION=VAR in the hooks/scripts.

Since this isn't included in Debian initramfs-tools (for some unknown
reason), we need to amend the sysctl handling on Debian's kdump-tools
by adding more checks in both the hook and script, in order to avoid
them to run in regular boot.

The idea of having an extra patch for that is (a) to keep better code
sync with Ubuntu and commit organization, (b) expectation on including
the OPTION=VAR feature in Debian's initramfs-tools, hence this patch
might be reverted in the future.

Required-by-commit: "kdump-tools: Add sysctl override mechanism"
Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>

3 files changed, 36 insertions, 0 deletions

diff --git a/debian/initramfs.hook b/debian/initramfs.hook
index fdbde24..5628331 100644
--- a/debian/initramfs.hook
+++ b/debian/initramfs.hook
@@ -2,6 +2,10 @@
 #
 # This kdump-tools hook includes kdump sysctl overrides to the
 # kdump minimal initrd.
+#
+# OPTION=VAR is a control provided only by Ubuntu initramfs-tools,
+# so this is innocuous and harmless on Debian - kept here for
+# better code sync between Debian and Ubuntu.
 OPTION=KDUMP
 
 PREREQ=""
@@ -17,6 +21,14 @@ prereqs)
 	;;
 esac
 
+# In Debian we don't have the fine-tuned control of what hooks to run
+# based on OPTION=VAR (like Ubuntu). So, we need the folowing check
+# in order to prevent this hook to run for regular initrds - it should
+# only be executed for kdump smaller initrd.
+if [ "${CONFDIR}" != "/var/lib/kdump/initramfs-tools" ]; then
+	exit 0
+fi
+
 . /usr/share/initramfs-tools/hook-functions
 
 KDUMP_SYSCTL_PATH="/etc/kdump/sysctl.conf"
diff --git a/debian/initramfs.local-bottom b/debian/initramfs.local-bottom
index 1bfb0a6..f099138 100644
--- a/debian/initramfs.local-bottom
+++ b/debian/initramfs.local-bottom
@@ -4,6 +4,15 @@
 # the sysctl settings present on file /etc/kdump/sysctl.conf.
 # Only kdump minimal initrd contains this script - regular initrds won't
 # get this script included, since KDUMP variable is not set by default.
+#
+# Well....this is not entirely true in Debian. Due to initramfs-tools
+# on Debian lacking the OPTION=VAR feature (present in Ubuntu) to
+# control which scripts get included in initrd (based on the OPTION
+# value), this script *will* be included in regular initrd also.
+# But we have a check below to prevent it from doing the sysctls
+# overriding. We chose to kept the innocuous OPTION here to better
+# code sync with Ubuntu.
+
 OPTION=KDUMP
 
 set +e
@@ -13,6 +22,15 @@ case "${1}" in
                 ;;
 esac
 
+# In Debian we don't have the fine-tuned control of what scripts should
+# be included in the initrd based on OPTION=VAR (like Ubuntu). So, we
+# need the folowing check in order to prevent this script from running
+# on regular initrds - it should only be executed on kdump boot.
+VMCORE_FILE=/proc/vmcore
+if [ ! -e $VMCORE_FILE ]; then
+	exit 0
+fi
+
 KDUMP_SYSCTL_PATH="/etc/kdump/sysctl.conf"
 # Do not prevent the system boot on error, kdump may be the last resource!
 if [ ! -d /run ]; then
diff --git a/debian/kernel-postinst-generate-initrd b/debian/kernel-postinst-generate-initrd
index bad88b4..548f50c 100755
--- a/debian/kernel-postinst-generate-initrd
+++ b/debian/kernel-postinst-generate-initrd
@@ -58,6 +58,12 @@ fi
 
 # Mark our custom initramfs.conf to indicate that kdump-tools
 # hooks/scripts should run/get included in our minimal initrd.
+#
+# Unfortunately, this is not true for Debian. OPTION=VAR is a
+# control provided only by Ubuntu initramfs-tools, so this is
+# innocuous /harmless on Debian - kept here for better code
+# sync between Debian and Ubuntu. We needed special checks on
+# hook/script in Debian to prevent them on regular initrd.
 echo "KDUMP=y" >> $initramfsdir/initramfs.conf
 
 # Cleaning up existing initramfs with same version