linux-stable.git/include/linux/watchdog.h, branch v4.5.3

watchdog: Drop pointer to watchdog device from struct watchdog_device

2016-01-11T20:53:59+00:00

The lifetime of the watchdog device pointer is different from the lifetime
of its character device. Remove it entirely to avoid race conditions.

Signed-off-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Add support for creating driver specific sysfs attributes

2016-01-11T20:53:57+00:00

The Zodiac watchdog driver attaches additional sysfs attributes to the
watchdog device. This has a number of problems: The watchdog device
lifetime differs from the driver lifetime, and the device structure
should therefore not be accessed from drivers. Also, creating sysfs
attributes after driver registration results in a potential race condition
if user space expects the attributes to exist but they don't exist yet.

Add support for creating driver specific sysfs attributes to the watchdog
core to solve the problems.

Signed-off-by: Guenter Roeck 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: kill unref/ref ops

2016-01-11T20:52:51+00:00

ref/unref ops are not called at all so even marked them as deprecated
is misleading, we need to just drop the API.

Signed-off-by: Tomas Winkler 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Separate and maintain variables based on variable lifetime

2015-12-29T19:36:03+00:00

All variables required by the watchdog core to manage a watchdog are
currently stored in struct watchdog_device. The lifetime of those
variables is determined by the watchdog driver. However, the lifetime
of variables used by the watchdog core differs from the lifetime of
struct watchdog_device. To remedy this situation, watchdog drivers
can implement ref and unref callbacks, to be used by the watchdog
core to lock struct watchdog_device in memory.

While this solves the immediate problem, it depends on watchdog drivers
to actually implement the ref/unref callbacks. This is error prone,
often not implemented in the first place, or not implemented correctly.

To solve the problem without requiring driver support, split the variables
in struct watchdog_device into two data structures - one for variables
associated with the watchdog driver, one for variables associated with
the watchdog core. With this approach, the watchdog core can keep track
of its variable lifetime and no longer depends on ref/unref callbacks
in the driver. As a side effect, some of the variables originally in
struct watchdog_driver are now private to the watchdog core and no longer
visible in watchdog drivers.

As a side effect of the changes made, an ioctl will now always fail
with -ENODEV after a watchdog device was unregistered with the character
device still open. Previously, it would only fail with -ENODEV in some
situations. Also, ioctl operations are now atomic from driver perspective.
With this change, it is now guaranteed that the driver will not unregister
a watchdog between a timeout change and the subsequent ping.

The 'ref' and 'unref' callbacks in struct watchdog_driver are no longer
used and marked as deprecated.

Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: core: add reboot notifier support

2015-12-13T14:55:51+00:00

Many watchdog drivers register a reboot notifier in order to stop the
watchdog on system reboot. Thus we can factorize this code in the
watchdog core.

For that purpose, a new notifier block is added in watchdog_device for
internal use only, as well as a new watchdog_stop_on_reboot helper
function.

If this helper is called, watchdog core registers the related notifier
block and will stop the watchdog when SYS_HALT or SYS_DOWN is received.

Since this operation can be critical on some platforms, abort the device
registration if the reboot notifier registration fails.

Suggested-by: Vivien Didelot 
Signed-off-by: Damien Riegel 
Reviewed-by: Vivien Didelot 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: core: add restart handler support

2015-12-13T14:27:10+00:00

Many watchdog drivers implement the same code to register a restart
handler. This patch provides a generic way to set such a function.

The patch adds a new restart watchdog operation. If a restart priority
greater than 0 is needed, the driver can call
watchdog_set_restart_priority to set it.

Suggested-by: Vivien Didelot 
Signed-off-by: Damien Riegel 
Reviewed-by: Guenter Roeck 
Reviewed-by: Vivien Didelot 
Signed-off-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: include: add units for timeout values in kerneldoc

2015-11-03T19:46:26+00:00

Signed-off-by: Wolfram Sang 
Reviewed-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: include: fix some typos

2015-11-03T19:46:21+00:00

Signed-off-by: Wolfram Sang 
Reviewed-by: Guenter Roeck 
Signed-off-by: Wim Van Sebroeck

watchdog: Always evaluate new timeout against min_timeout

2015-11-03T13:34:22+00:00

Up to now, a new timeout value is only evaluated against min_timeout
if max_timeout is provided. This does not really make sense; a driver
can have a minimum timeout even if it does not have a maximum timeout.
Ensure that it is not smaller than min_timeout, even if max_timeout
is not set.

Signed-off-by: Guenter Roeck 
Acked-by: Uwe Kleine-König 
Signed-off-by: Wim Van Sebroeck

kernel/watchdog: move NMI function header declarations from watchdog.h to nmi.h

2015-09-04T23:54:41+00:00

The kernel's NMI watchdog has nothing to do with the watchdog subsystem.
Its header declarations should be in linux/nmi.h, not linux/watchdog.h.

The code provided two sets of dummy functions if HARDLOCKUP_DETECTOR is
not configured, one in the include file and one in kernel/watchdog.c.
Remove the dummy functions from kernel/watchdog.c and use those from the
include file.

Signed-off-by: Guenter Roeck 
Cc: Stephane Eranian 
Cc: Peter Zijlstra (Intel) 
Cc: Ingo Molnar 
Cc: Don Zickus 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds