commit 4cd13c21b2 ("softirq: Let ksoftirqd do its job") has the
effect of deferring timer handling in case of high CPU load, hence
delaying the delayed work allthought the worker is running which
high realtime priority.
As hrtimers are not managed by softirqs, this patch replaces the
delayed work by a plain work and uses an hrtimer to schedule that work.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Guenter Roeck <Linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
When running a command like 'chrt -f 50 dd if=/dev/zero of=/dev/null',
the watchdog_worker fails to service the HW watchdog and the
HW watchdog fires long before the watchdog soft timeout.
At the moment, the watchdog_worker is invoked as a delayed work.
Delayed works are handled by non realtime kernel threads. The
WQ_HIGHPRI flag only increases the niceness of that threads.
This patch replaces the delayed work logic by kthread delayed work,
and sets the associated kernel task to SCHED_FIFO with the highest
priority, in order to ensure that the watchdog worker will run as
soon as possible.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Notice that in this particular case I replaced "Fall" with a proper
"fall through" comment, which is what GCC is expecting to find.
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
If handle_boot_enabled is set to 0, the watchdog driver module use
counter will not be increased and kref_get() will not be called when
registering the watchdog. Subsequently, on open, this does not happen
either because the code believes that it was already done because the
hardware watchdog is marked as running.
We could introduce a state variable to indicate this state, but let's
just increase the module use counter and call kref_get() unconditionally
if the hardware watchdog is running when a driver is registering itself
to keep the code simple.
Fixes: 2501b01531 ("watchdog: core: add option to avoid early ...")
Cc: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
If a watchdog driver's open function sets WDOG_HW_RUNNING with the
expectation that the watchdog can not be stopped, but then stops the
watchdog anyway in its stop function, kref_get() wil not be called in
watchdog_open(). If the watchdog then stops on close, WDOG_HW_RUNNING
will be cleared and kref_put() will be called, causing a kref imbalance.
As result the character device data structure will be released, which in
turn will cause the system to crash on the next call to watchdog_open().
Fixes: ee142889e3 ("watchdog: Introduce WDOG_HW_RUNNING flag")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Save a bit of cleanup code by leveraging newly added
devm_register_reboot_notifier().
[akpm@linux-foundation.org: small cleanup: avoid 80-col tricks]
Link: http://lkml.kernel.org/r/20170411160615.9784-1-andrew.smirnov@gmail.com
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This will be useful when the condition becomes slightly more
complicated in the next patch.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Esben Haabendal <esben@haabendal.dk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
On some systems its desirable to have watchdog reboot the system
when it does not come up fast enough. This adds a kernel parameter
to disable the auto-update of watchdog before userspace takes over
and a kernel option to set the default. The info messages were
added to shorten error searching on misconfigured systems.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Many watchdog drivers explicitly stop the watchdog when unregistering it.
While it is unclear if this is actually needed (the whatdog should not be
running at that time if it can be stopped), introduce a helper to
explicitly stop the watchdog in the watchdog core when unregistering it.
This helps reducing driver code size while retaining functionality.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The change adds an option to a user with CONFIG_WATCHDOG_SYSFS and
CONFIG_WATCHDOG_PRETIMEOUT_GOV enabled to get information about all
registered watchdog pretimeout governors by reading watchdog device
attribute named "pretimeout_available_governors".
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
The change converts watchdog device attribute "pretimeout_governor" from
read-only to read-write type to allow users to select a desirable
watchdog pretimeout governor in runtime, e.g.
% echo -n panic > /sys/..../watchdog/watchdog0/pretimeout
To get this working a list of registered pretimeout governors is created
and a new helper function watchdog_pretimeout_governor_set() is exported
to watchdog_dev.c.
If a selected governor is gone, a watchdog device pretimeout notification
is delegated to a default built-in pretimeout governor.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
The change adds a simple watchdog pretimeout framework infrastructure,
its purpose is to allow users to select a desired handling of watchdog
pretimeout events, which may be generated by some watchdog devices.
A user selects a default watchdog pretimeout governor during
compilation stage.
Watchdogs with WDIOF_PRETIMEOUT capability now have one more device
attribute in sysfs, pretimeout_governor attribute is intended to display
the selected watchdog pretimeout governor.
The framework has no impact at runtime on watchdog devices with no
WDIOF_PRETIMEOUT capability set.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Since the watchdog framework centrializes the IOCTL interfaces of device
drivers now, SETPRETIMEOUT and GETPRETIMEOUT need to be added in the
common code.
Signed-off-by: Robin Gong <b38343@freescale.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[vzapolskiy: added conditional pretimeout sysfs attribute visibility]
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
WDOG_HW_RUNNING indicates that the hardware watchdog is running while the
watchdog device is closed. The flag may be set by the driver when it is
instantiated to indicate that the watchdog is running, and that the
watchdog core needs to send heartbeat requests to the driver until the
watchdog device is opened.
When the watchdog device is closed, the flag can be used by the driver's
stop function to indicate to the watchdog core that it was unable to stop
the watchdog, and that the watchdog core needs to send heartbeat requests.
This only works if the flag is actually cleared when the watchdog is
stopped. To avoid having to clear the flag in each driver's stop function,
clear it in the watchdog core before calling the stop function.
Reported-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Fixes: ee142889e3 ("watchdog: Introduce WDOG_HW_RUNNING flag")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Up to now, the watchdog status function called a driver function,
which was supposed to return the watchdog status. All but one
driver using the watchdog core did not implement this function,
and the driver implementing it did not implement it correctly
(the function is supposed to return WDIOF_ flags). At the same time,
at least some of the status information can be provided by the watchdog
core.
Provide the available status bits directly from the watchdog driver core.
Call the driver status function if it exists to get the boot status, but
always provide WDIOF_MAGICCLOSE and WDIOF_KEEPALIVEPING internally.
This patch makes the 'status' sysfs attribute always available.
This attribute is now displayed as hex number with 0x prepended to be
easier to decode.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
If the driver indicates that the watchdog is running, the framework
should feed it until userspace opens the device, regardless of whether
the driver has set max_hw_heartbeat_ms.
This patch only affects the case where wdd->max_hw_heartbeat_ms is
zero, wdd->timeout is non-zero, the watchdog is not active and the
hardware device is running (*):
- If wdd->timeout is zero, watchdog_need_worker() returns false both
before and after this patch, and watchdog_next_keepalive() is not
called.
- If watchdog_active(wdd), the return value from watchdog_need_worker
is also the same as before (namely, hm && t > hm). Hence in that case,
watchdog_next_keepalive() is only called if hm == max_hw_heartbeat_ms
is non-zero, so the change to min_not_zero there is a no-op.
- If the watchdog is not active and the device is not running, we
return false from watchdog_need_worker just as before.
That leaves the watchdog_hw_running(wdd) && !watchdog_active(wdd) &&
wdd->timeout case. Again, it's easy to see that if
wdd->max_hw_heartbeat_ms is non-zero, we return true from
watchdog_need_worker with and without this patch, and the logic in
watchdog_next_keepalive is unchanged. Finally, if
wdd->max_hw_heartbeat_ms is 0, we used to end up in the
cancel_delayed_work branch, whereas with this patch we end up
scheduling a ping timeout_ms/2 from now.
(*) This should imply that no current kernel drivers are affected,
since the only drivers which explicitly set WDOG_HW_RUNNING are
imx2_wdt.c and dw_wdt.c, both of which also provide a non-zero value
for max_hw_heartbeat_ms. The watchdog core also sets WDOG_HW_RUNNING,
but only when the driver doesn't provide ->stop, in which case it
must, according to Documentation/watchdog/watchdog-kernel-api.txt, set
max_hw_heartbeat_ms.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
lockdep reports the following circular locking dependency.
======================================================
INFO: possible circular locking dependency detected ]
4.6.0-rc3-00191-gfabf418 #162 Not tainted
-------------------------------------------------------
systemd/1 is trying to acquire lock:
((&(&wd_data->work)->work)){+.+...}, at: [<80141650>] flush_work+0x0/0x280
but task is already holding lock:
(&wd_data->lock){+.+...}, at: [<804acfa8>] watchdog_release+0x18/0x190
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&wd_data->lock){+.+...}:
[<80662310>] mutex_lock_nested+0x64/0x4a8
[<804aca4c>] watchdog_ping_work+0x18/0x4c
[<80143128>] process_one_work+0x1ac/0x500
[<801434b4>] worker_thread+0x38/0x554
[<80149510>] kthread+0xf4/0x108
[<80107c10>] ret_from_fork+0x14/0x24
-> #0 ((&(&wd_data->work)->work)){+.+...}:
[<8017c4e8>] lock_acquire+0x70/0x90
[<8014169c>] flush_work+0x4c/0x280
[<801440f8>] __cancel_work_timer+0x9c/0x1e0
[<804acfcc>] watchdog_release+0x3c/0x190
[<8022c5e8>] __fput+0x80/0x1c8
[<80147b28>] task_work_run+0x94/0xc8
[<8010b998>] do_work_pending+0x8c/0xb4
[<80107ba8>] slow_work_pending+0xc/0x20
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&wd_data->lock);
lock((&(&wd_data->work)->work));
lock(&wd_data->lock);
lock((&(&wd_data->work)->work));
*** DEADLOCK ***
1 lock held by systemd/1:
stack backtrace:
CPU: 2 PID: 1 Comm: systemd Not tainted 4.6.0-rc3-00191-gfabf418 #162
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[<8010f5e4>] (unwind_backtrace) from [<8010c038>] (show_stack+0x10/0x14)
[<8010c038>] (show_stack) from [<8039d7fc>] (dump_stack+0xa8/0xd4)
[<8039d7fc>] (dump_stack) from [<80177ee0>] (print_circular_bug+0x214/0x334)
[<80177ee0>] (print_circular_bug) from [<80179230>] (check_prevs_add+0x4dc/0x8e8)
[<80179230>] (check_prevs_add) from [<8017b3d8>] (__lock_acquire+0xc6c/0x14ec)
[<8017b3d8>] (__lock_acquire) from [<8017c4e8>] (lock_acquire+0x70/0x90)
[<8017c4e8>] (lock_acquire) from [<8014169c>] (flush_work+0x4c/0x280)
[<8014169c>] (flush_work) from [<801440f8>] (__cancel_work_timer+0x9c/0x1e0)
[<801440f8>] (__cancel_work_timer) from [<804acfcc>] (watchdog_release+0x3c/0x190)
[<804acfcc>] (watchdog_release) from [<8022c5e8>] (__fput+0x80/0x1c8)
[<8022c5e8>] (__fput) from [<80147b28>] (task_work_run+0x94/0xc8)
[<80147b28>] (task_work_run) from [<8010b998>] (do_work_pending+0x8c/0xb4)
[<8010b998>] (do_work_pending) from [<80107ba8>] (slow_work_pending+0xc/0x20)
Turns out the call to cancel_delayed_work_sync() in watchdog_release()
is not necessary and can be dropped. If the worker is no longer necessary,
the subsequent call to watchdog_update_worker() will cancel it. If it is
already running, it won't do anything, since the worker function checks
if it needs to ping the watchdog or not.
Reported-by: Clemens Gruber <clemens.gruber@pqgruber.com>
Tested-by: Clemens Gruber <clemens.gruber@pqgruber.com>
Fixes: 11d7aba9ce ("watchdog: imx2: Convert to use infrastructure triggered keepalives")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: stable <stable@vger.kernel.org>
Smatch rightfully complains that wdd is dereferenced in the watchdog
release function after being checked for NULL. Also make sure that it
is not accessed outside mutex protection to avoid use-after-free problems.
Fixes: e6c71e84e4c0 ("watchdog: Introduce WDOG_HW_RUNNING flag")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Some watchdogs require a minimum time between heartbeats.
Examples are the watchdogs in DA9062 and AT91SAM9x.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Not all hardware watchdogs can be stopped. The driver for
such watchdogs would typically only set the WATCHDOG_HW_RUNNING
flag in its stop function. Make the stop function optional and set
WATCHDOG_HW_RUNNING in the watchdog core if it is not provided.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
The WDOG_HW_RUNNING flag is expected to be set by watchdog drivers if
the hardware watchdog is running. If the flag is set, the watchdog
subsystem will ping the watchdog even if the watchdog device is closed.
The watchdog driver stop function is now optional and may be omitted
if the watchdog can not be stopped. If stopping the watchdog is not
possible but the driver implements a stop function, it is responsible
to set the WDOG_HW_RUNNING flag in its stop function.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Introduce an optional hardware maximum heartbeat in the watchdog core.
The hardware maximum heartbeat can be lower than the maximum timeout.
Drivers can set the maximum hardware heartbeat value in the watchdog data
structure. If the configured timeout exceeds the maximum hardware heartbeat,
the watchdog core enables a timer function to assist sending keepalive
requests to the watchdog driver.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
For some watchdogs, the watchdog driver handles timeout changes without
explicitly setting any registers. In this situation, the watchdog driver
might only set the 'timeout' variable but do nothing else.
This can as well be handled by the infrastructure, so make the set_timeout
callback optional. If WDIOF_SETTIMEOUT is configured but the .set_timeout
callback is not available, update the timeout variable in the
infrastructure code.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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 <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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 <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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 <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
The watchdog character device is currently created in watchdog_dev.c,
and the watchdog device in watchdog_core.c. This results in
cross-dependencies, since device creation needs to know the watchdog
character device number as well as the watchdog class, both of which
reside in watchdog_dev.c.
Create the watchdog device in watchdog_dev.c to simplify the code.
Inspired by earlier patch set from Damien Riegel.
Cc: Damien Riegel <damien.riegel@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This patch adds following attributes to watchdog device's sysfs interface
to read its different status.
* state - reads whether device is active or not
* identity - reads Watchdog device's identity string.
* timeout - reads current timeout.
* timeleft - reads timeleft before watchdog generates a reset
* bootstatus - reads status of the watchdog device at boot
* status - reads watchdog device's internal status bits
* nowayout - reads whether nowayout feature was set or not
Testing with iTCO_wdt:
# cd /sys/class/watchdog/watchdog1/
# ls
bootstatus dev device identity nowayout power state
subsystem timeleft timeout uevent
# cat identity
iTCO_wdt
# cat timeout
30
# cat state
inactive
# echo > /dev/watchdog1
# cat timeleft
26
# cat state
active
# cat bootstatus
0
# cat nowayout
0
Signed-off-by: Pratyush Anand <panand@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
We need few sysfs attributes to know different status of a watchdog device.
To do that, we need to associate .dev_groups with watchdog_class. So
convert it from pointer to static.
Putting this static struct in watchdog_dev.c, so that static device
attributes defined in that file can be attached to it.
Signed-off-by: Pratyush Anand <panand@redhat.com>
Suggested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Watchdog ping return errors are ignored by watchdog core,
Whatchdog daemon should be informed about possible hardware error or
underlaying device driver get unregistered.
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
The current code uses 'wdd', wddev', and 'watchdog' as variable names
for struct watchdog_device. This is confusing and makes it difficult
to enhance the code. Replace it all with 'wdd'.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: Timo Kokkonen <timo.kokkonen@offcode.fi>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
A watchdog device may be stopped from userspace using WDIOC_SETOPTIONS
ioctl and flag WDIOS_DISABLECARD. If the device is closed after this
operation, watchdog_release() is called and status bits checked for
stopping it. Besides, if the device has not been unregistered a critical
message "watchdog did not stop!" is printed, although the ioctl may have
successfully stopped it already.
Without the patch a user application sample code like this will successfully
stop the watchdog, but the kernel will output the message
"watchdog did not stop!":
wd_fd = open("/dev/watchdog", O_RDWR);
flags = WDIOS_DISABLECARD;
ioctl(wd_fd, WDIOC_SETOPTIONS, &flags);
close(wd_fd);
Signed-off-by: Hector Palacios <hector.palacios@digi.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
A race condition exists when registering the first watchdog device.
Sequence of events:
- watchdog_register_device calls watchdog_dev_register
- watchdog_dev_register creates the watchdog misc device by calling
misc_register.
At that time, the matching character device (/dev/watchdog0) does not yet
exist, and old_wdd is not set either.
- Userspace gets an event and opens /dev/watchdog
- watchdog_open is called and sets wdd = old_wdd, which is still NULL,
and tries to dereference it. This causes the kernel to panic.
Seen with systemd trying to open /dev/watchdog immediately after
it was created.
Reported-by: Arkadiusz Miskiewicz <arekm@maven.pl>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Arkadiusz Miskiewicz <arekm@maven.pl>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Add support for watchdog drivers to initialize/set the timeout field
of the watchdog_device structure. The timeout field is initialised
either with the module timeout parameter value (if valid) or with the
timeout-sec dt property (if valid). If both are invalid the initial
value is unchanged.
Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
In commit 7a87982420 we added
a wrapper for the WDIOC_GETSTATUS ioctl call. The code results
however in a different behaviour: it returns an error if the
driver doesn't support the status operation. This is not
according to the API that says that when we don't support
the status operation, that we just should return a 0 value.
Only when the device isn't there anymore, we should return an
error.
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
If a driver's watchdog_device struct is part of a dynamically allocated
struct (which it often will be), merely locking the module is not enough,
even with a drivers module locked, the driver can be unbound from the device,
examples:
1) The root user can unbind it through sysfd
2) The i2c bus master driver being unloaded for an i2c watchdog
I will gladly admit that these are corner cases, but we still need to handle
them correctly.
The fix for this consists of 2 parts:
1) Add ref / unref operations, so that the driver can refcount the struct
holding the watchdog_device struct and delay freeing it until any
open filehandles referring to it are closed
2) Most driver operations will do IO on the device and the driver should not
do any IO on the device after it has been unbound. Rather then letting each
driver deal with this internally, it is better to ensure at the watchdog
core level that no operations (other then unref) will get called after
the driver has called watchdog_unregister_device(). This actually is the
bulk of this patch.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This patch fixes some potential multithreading issues, despite only
allowing one process to open the /dev/watchdog device, we can still get
called multiple times at the same time, since a program could be using thread,
or could share the fd after a fork.
This causes 2 potential problems:
1) watchdog_start / open do an unlocked test_n_set / test_n_clear,
if these 2 race, the watchdog could be stopped while the active
bit indicates it is running or visa versa.
2) Most watchdog_dev drivers probably assume that only one
watchdog-op will get called at a time, this is not necessary
true atm.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Rewrite and extend the wrapper code so that we can easily introduce
locking (this to be able to prevent potential multithreading issues).
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
While they are registered all our watchdogs now have a valid device object
so we can in turn use that to report problems nicely.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Create the watchdog class and it's associated devices.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
We keep the old /dev/watchdog interface file for the first watchdog via
miscdev. This is basically a cut and paste of the relevant interface code
from the rtc driver layer tweaked for watchdog.
Revised to fix problems noted by Hans de Goede
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
The watchdog_core include file should have been named
watchdog_core.h and not watchdog_dev.h . Correct this.
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Some watchdog may need to check if watchdog is ACTIVE or not, for example in
their suspend/resume hooks.
This patch adds this routine and changes the core drivers to use it.
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Include the private watchdog_dev.h header to pickup the prototypes for the
watchdog_dev_register/unregister functions.
This quiets the following sparse warnings:
warning: symbol 'watchdog_dev_register' was not declared. Should it be static?
warning: symbol 'watchdog_dev_unregister' was not declared. Should it be static?
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This patch adds support for WDIOC_GETTIMELEFT IOCTL in watchdog core. So, there
is another function pointer added to struct watchdog_ops, which can be passed by
drivers to support this IOCTL.
Related documentation is updated too.
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
When a set_timeout operation succeeds this does not necessarily mean that
the exact timeout requested has been achieved, because the watchdog does not
necessarily have a 1 second resolution. So rather then have the core set
the timeout member of the watchdog_device struct to the exact requested
value, instead the driver should set it to the actually achieved timeout value.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Use the current logging styles.
Make sure all output has a prefix.
Add missing newlines.
Remove now unnecessary PFX, NAME, and miscellaneous other #defines.
Coalesce formats.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Use the passed watchdog_device instead of the static global variable when
testing and setting the status in watchdog_ping, watchdog_start, and
watchdog_stop. Note that the callers of these functions are actually
passing the static global variable.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Add min_timeout (minimum timeout) and max_timeout
values so that the framework can check if the new
timeout value is between the minimum and maximum
timeout values. If both values are 0, then the
framework will leave the check for the watchdog
device driver itself.
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Christophe Leroy