Install kernel module for active watchdog

Recently following patches have been added in upstream Linux kernel, which
(1) fixes parent of watchdog_device so that /sys/class/watchdog/watchdogn/device is populated. (2) adds some sysfs device attributes so that different watchdog status can be read.

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6551881c86c791237a3bebf11eb3bd70b60ea782
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=906d7a5cfeda508e7361f021605579a00cd82815
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=33b711269ade3f6bc9d9d15e4343e6fa922d999b

With the above support, now we can find out whether a watchdog is active or not. We can also find out the driver/module responsible for that watchdog device.

Proposed patch uses above support and then adds module of active watchdog in initramfs generated by dracut for hostonly mode. Kernel module for inactive watchdog will be added as well for none hostonly mode.

When an user does not want to add kernel module, then one should exclude complete dracut watchdog module with --omit.

Testing:
-- When watchdog is active watchdog modules were added

	# cat /sys/class/watchdog/watchdog0/identity
	iTCO_wdt
	# cat /sys/class/watchdog/watchdog0/state
	active
	# dracut --hostonly initramfs-test.img -a watchdog
	# lsinitrd initramfs-test.img | grep iTCO
	-rw-r--r--   1 root     root         9100 Feb 24 09:19 usr/lib/modules/.../kernel/drivers/watchdog/iTCO_vendor_support.ko
	-rw-r--r--   1 root     root        19252 Feb 24 09:19 usr/lib/modules/.../kernel/drivers/watchdog/iTCO_wdt.ko

-- When watchdog is inactive then watchdog modules were not added

	# cat /sys/class/watchdog/watchdog0/state
	inactive
	# dracut --hostonly initramfs-test.img -a watchdog
	# lsinitrd initramfs-test.img | grep iTCO

-- When watchdog is inactive, but no hostonly mode, watchdog modules were added

	# cat /sys/class/watchdog/watchdog0/state
	inactive
	# dracut --no-hostonly initramfs-test.img -a watchdog
	# lsinitrd initramfs-test.img | grep iTCO
	-rw-r--r--   1 root     root         9100 Feb 24 09:19 usr/lib/modules/.../kernel/drivers/watchdog/iTCO_vendor_support.ko
	-rw-r--r--   1 root     root        19252 Feb 24 09:19 usr/lib/modules/.../kernel/drivers/watchdog/iTCO_wdt.ko

Signed-off-by Pratyush Anand <[email protected]>

Cc Dave Young <[email protected]>

Cc Don Zickus <[email protected]>

Cc Harald Hoyer <[email protected]>

---
 modules.d/04watchdog/module-setup.sh | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

modules.d/04watchdog/module-setup.sh +0 -0

index 7ec757aec032..0ffaa9658502 100755

modules.d/04watchdog/module-setup.sh install() { · line 41

Quoted 2 lines · Pratyush Anand

modules.d/04watchdog/module-setup.sh +2 -0

+	    active=$(< "$dir/state")
+	    ! [[ $hostonly ]] || [[ "$active" =  "active" ]] || continue

Even if for devices which is not active it is still a hostonly device because it being detected by kernel running on the host?

But I will not stick to this issue, I'm fine if Harald is ok with it because I do not know how to handle non hostonly in a proper way ..

It is expected that a watchdog module will disable an active watchdog when its probe is called ie, when it is loaded. So an early load of the module will help to disable it earlier.
This can be helpful in some corner cases where kdump and watchdog daemon both are active.

Testing:
-- When watchdog kernel modules were added
# dracut --no-hostonly initramfs-test.img -a watchdog # lsinitrd initramfs-test.img -f etc/cmdline.d/04-watchdog.conf rd.driver.pre=iTCO_wdt,lpc_ich,

Signed-off-by Pratyush Anand <[email protected]>

Cc Dave Young <[email protected]>

Cc Don Zickus <[email protected]>

Cc Harald Hoyer <[email protected]>

---
 modules.d/04watchdog/module-setup.sh | 5 +++++
 1 file changed, 5 insertions(+)

modules.d/04watchdog/module-setup.sh +2 -0

index 0ffaa9658502..d99e5b33de44 100755
@@ -34,6 +34,7 @@ install() {
 
 installkernel() {
     [[ -d /sys/class/watchdog/ ]] || return
+    wdtcmdline=""
     for dir in /sys/class/watchdog/*; do
 	    [[ -d "$dir" ]] || continue
 	    [[ -f "$dir/state" ]] || continue

@@ -47,6 +48,7 @@ installkernel() {
 	    # represented by modalias
 	    wdtdrv=$(modprobe -R $wdtdrv)
 	    instmods $wdtdrv
+	    wdtcmdline="$wdtcmdline$(echo $wdtdrv | tr " " ","),"
 	    # however in some cases, we also need to check that if there is
 	    # a specific driver for the parent bus/device.  In such cases
 	    # we also need to enable driver for parent bus/device.

Quoted 1 line

+ [[ $wdtcmdline = "" ]] || echo "rd.driver.pre=$wdtcmdline" > ${initdir}/etc/cmdline.d/04-watchdog.conf

It is not necessary to use same number as the dracut module "04".
Since it is special we want it being loaded as soon as possible move it to 00-watchdog.conf sound better.

Changes since V3:
-- Incorporated changes suggested by Harald for V2 patches

Changes since V2:
-- Added one more patch to update rd.driver.pre with watchdog module name, so that they are loaded into kernel as early as possible.
-- Removed creation of tmp/active-watchdogs. modinfo will be helpful for kexec-tools.

Quoted 2 lines · Pratyush Anand

-- Removed creation of tmp/active-watchdogs. modinfo will be helpful for kexec-tools.

Kdump still need save a previous added wdt somewhere so that it can rebuild initrd if necessary. I'm not sure where can we store the state, do you have some thoughts about it?