Bug 104951

Summary:	mei_me module silently creates watchdog device, tells no one and runs away and hides
Product:	Other	Reporter:	Tim Small (tim)
Component:	Modules	Assignee:	other_modules
Status:	NEW ---
Severity:	normal
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	4.2.0	Subsystem:
Regression:	No	Bisected commit-id:

Description Tim Small 2015-09-24 13:51:41 UTC

The mei_me module creates a watchdog device, but produces no info statements to inform the administrator, neither is the module name obvious, neither is there any way to disable the watchdog functionality if it is now wanted (or doesn't work etc. so that they admin would like to use an alternative watchdog device also present on the systems).

It isn't possible to detect which module has created the watchdog device via sysfs either:

# udevadm info /dev/watchdog
Unknown device, --name=, --path=, or absolute path in /dev/ or /sys expected.
# modprobe mei_me
# udevadm info /dev/watchdog
P: /devices/virtual/misc/watchdog
N: watchdog
E: DEVNAME=/dev/watchdog
E: DEVPATH=/devices/virtual/misc/watchdog
E: MAJOR=10
E: MINOR=130
E: SUBSYSTEM=misc


The only mechanism available to users who need to disable this functionality at present is to blacklist the mei_me module entirely (which on some platforms appears to adversely impact battery life).

It would be nice if some or all the following changes were made:

. Log at info level the creation of the device
. Make device owner info available via sysfs
. Split the watchdog functionality out into a separate kernel module

Comment 1 Tim Small 2015-09-24 13:57:28 UTC

Failing the option to split out the watchdog into a separate kernel module, it would be nice to be able to disable the watchdog functionality e.g. with a module parameter.

Maintainer is listed as in MAINTAINERS: tomas.winkler@intel.com