watchdog: set cdev owner before adding

[ Upstream commit 38d75297745f04206db9c29bdd75557f0344c7cc ]

When the new watchdog character device is registered, it becomes
available for opening. This crea

watchdog: set cdev owner before adding

[ Upstream commit 38d75297745f04206db9c29bdd75557f0344c7cc ]

When the new watchdog character device is registered, it becomes
available for opening. This creates a race where userspace may open the
device before the character device's owner is set. This results in an
imbalance in module_get calls as the cdev_get in cdev_open will not
increment the reference count on the watchdog driver module.

This causes problems when the watchdog character device is released as
the module loader's reference will also be released. This makes it
impossible to open the watchdog device later on as it now appears that
the module is being unloaded. The open will fail with -ENXIO from
chrdev_open.

The legacy watchdog device will fail with -EBUSY from the try_module_get
in watchdog_open because it's module owner is the watchdog core module
so it can still be opened but it will fail to get a refcount on the
underlying watchdog device driver.

Fixes: 72139dfa2464 ("watchdog: Fix the race between the release of watchdog_core_data and cdev")
Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20231205190522.55153-1-curtis.klein@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

watchdog: core: Always set WDOG_HW_RUNNING when starting watchdog

The use of WDOG_HW_RUNNING is currently inconsistent: If set by the
driver, it will remain set until the watchdog device is opened a

watchdog: core: Always set WDOG_HW_RUNNING when starting watchdog

The use of WDOG_HW_RUNNING is currently inconsistent: If set by the
driver, it will remain set until the watchdog device is opened and then
closed. If set by the watchdog core, it is only set if the watchdog
can not be stopped when closed. Subsequenty it is always only set while
the watchdog is closed and the hardware watchdog is running.

This is both misleading and inconsistent: The API states that
watchdog_hw_running() indicates that the hardware watchdog is running.
This is currently not always the case. Set WDOG_HW_RUNNING whenever a
watchdog is successfully started for consistent behavior and to
accurately report its status.

This means that we no longer have to check for both watchdog_active()
and watchdog_hw_running() to check if the watchdog is running because
watchdog_hw_running() now implies watchdog_active(). Simplify the code
accordingly where warranted.

Cc: Wang Wensheng <wangwensheng4@huawei.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230304161607.1418952-1-linux@roeck-us.net
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

drivers: remove struct module * setting from struct class

There is no need to manually set the owner of a struct class, as the
registering function does it automatically, so remove all of the
explic

drivers: remove struct module * setting from struct class

There is no need to manually set the owner of a struct class, as the
registering function does it automatically, so remove all of the
explicit settings from various drivers that did so as it is unneeded.

This allows us to remove this pointer entirely from this structure going
forward.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230313181843.1207845-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

watchdog: report options in sysfs

This synchronizes the information reported by ioctl and sysfs.
The mismatch is confusing because "wdctl" from util-linux uses the ioctl
when used with root privileg

watchdog: report options in sysfs

This synchronizes the information reported by ioctl and sysfs.
The mismatch is confusing because "wdctl" from util-linux uses the ioctl
when used with root privileges and sysfs without.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221216-watchdog-sysfs-v2-2-6189311103a9@weissschuh.net
[groeck: Fixed continuation line alignment]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: report fw_version in sysfs

This synchronizes the information reported by ioctl and sysfs.
The mismatch is confusing because "wdctl" from util-linux uses the ioctl
when used with root privi

watchdog: report fw_version in sysfs

This synchronizes the information reported by ioctl and sysfs.
The mismatch is confusing because "wdctl" from util-linux uses the ioctl
when used with root privileges and sysfs without.

The file is called "fw_version" instead of "firmware_version" as
"firmware_version" is already used as custom attribute by single drivers.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221216-watchdog-sysfs-v2-1-6189311103a9@weissschuh.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Fix kmemleak in watchdog_cdev_register

kmemleak reports memory leaks in watchdog_dev_register, as follows:
unreferenced object 0xffff888116233000 (size 2048):
comm ""modprobe"", pid 2814

watchdog: Fix kmemleak in watchdog_cdev_register

kmemleak reports memory leaks in watchdog_dev_register, as follows:
unreferenced object 0xffff888116233000 (size 2048):
comm ""modprobe"", pid 28147, jiffies 4353426116 (age 61.741s)
hex dump (first 32 bytes):
80 fa b9 05 81 88 ff ff 08 30 23 16 81 88 ff ff .........0#.....
08 30 23 16 81 88 ff ff 00 00 00 00 00 00 00 00 .0#.............
backtrace:
[<000000007f001ffd>] __kmem_cache_alloc_node+0x157/0x220
[<000000006a389304>] kmalloc_trace+0x21/0x110
[<000000008d640eea>] watchdog_dev_register+0x4e/0x780 [watchdog]
[<0000000053c9f248>] __watchdog_register_device+0x4f0/0x680 [watchdog]
[<00000000b2979824>] watchdog_register_device+0xd2/0x110 [watchdog]
[<000000001f730178>] 0xffffffffc10880ae
[<000000007a1a8bcc>] do_one_initcall+0xcb/0x4d0
[<00000000b98be325>] do_init_module+0x1ca/0x5f0
[<0000000046d08e7c>] load_module+0x6133/0x70f0
...

unreferenced object 0xffff888105b9fa80 (size 16):
comm ""modprobe"", pid 28147, jiffies 4353426116 (age 61.741s)
hex dump (first 16 bytes):
77 61 74 63 68 64 6f 67 31 00 b9 05 81 88 ff ff watchdog1.......
backtrace:
[<000000007f001ffd>] __kmem_cache_alloc_node+0x157/0x220
[<00000000486ab89b>] __kmalloc_node_track_caller+0x44/0x1b0
[<000000005a39aab0>] kvasprintf+0xb5/0x140
[<0000000024806f85>] kvasprintf_const+0x55/0x180
[<000000009276cb7f>] kobject_set_name_vargs+0x56/0x150
[<00000000a92e820b>] dev_set_name+0xab/0xe0
[<00000000cec812c6>] watchdog_dev_register+0x285/0x780 [watchdog]
[<0000000053c9f248>] __watchdog_register_device+0x4f0/0x680 [watchdog]
[<00000000b2979824>] watchdog_register_device+0xd2/0x110 [watchdog]
[<000000001f730178>] 0xffffffffc10880ae
[<000000007a1a8bcc>] do_one_initcall+0xcb/0x4d0
[<00000000b98be325>] do_init_module+0x1ca/0x5f0
[<0000000046d08e7c>] load_module+0x6133/0x70f0
...

The reason is that put_device is not be called if cdev_device_add fails
and wdd->id != 0.

watchdog_cdev_register
wd_data = kzalloc [1]
err = dev_set_name [2]
..
err = cdev_device_add
if (err) {
if (wdd->id == 0) { // wdd->id != 0
..
}
return err; // [1],[2] would be leaked

To fix it, call put_device in all wdd->id cases.

Fixes: 72139dfa2464 ("watchdog: Fix the race between the release of watchdog_core_data and cdev")
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221116012714.102066-1-chenjun102@huawei.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Include <linux/kstrtox.h> when appropriate

The kstrto<something>() functions have been moved from kernel.h to
kstrtox.h.

So, in order to eventually remove <linux/kernel.h> from <linux/wat

watchdog: Include <linux/kstrtox.h> when appropriate

The kstrto<something>() functions have been moved from kernel.h to
kstrtox.h.

So, in order to eventually remove <linux/kernel.h> from <linux/watchdog.h>,
include the latter directly in the appropriate files.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/08fd5512e569558231247515c04c8596a1d11004.1667646547.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Add tracing events for the most usual watchdog events

To simplify debugging which process touches a watchdog and when, add
tracing events for .start(), .set_timeout(), .ping() and .stop().

watchdog: Add tracing events for the most usual watchdog events

To simplify debugging which process touches a watchdog and when, add
tracing events for .start(), .set_timeout(), .ping() and .stop().

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221008174602.3972859-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Check dev_set_name() return value

It's possible that dev_set_name() returns -ENOMEM, catch and handle this.

Signed-off-by: Bo Liu <liubo03@inspur.com>
Reviewed-by: Guenter Roeck <linux@ro

watchdog: Check dev_set_name() return value

It's possible that dev_set_name() returns -ENOMEM, catch and handle this.

Signed-off-by: Bo Liu <liubo03@inspur.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220920020312.2383-1-liubo03@inspur.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Improve watchdog_dev function documentation

Adjust function comments to the kernel doc format. It
also adjusts some variable names and adds return values.

No functional change.

Changes f

watchdog: Improve watchdog_dev function documentation

Adjust function comments to the kernel doc format. It
also adjusts some variable names and adds return values.

No functional change.

Changes from V1:
Change "Returns" to "Return:" (Randy Dunlap)

Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/30378a03e9cd9b5f6e92ec9bf512edc38bad8627.1644589712.git.bristot@kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Start watchdog in watchdog_set_last_hw_keepalive only if appropriate

We must not pet a running watchdog when handle_boot_enabled is off
because this will kick off automatic triggering befo

watchdog: Start watchdog in watchdog_set_last_hw_keepalive only if appropriate

We must not pet a running watchdog when handle_boot_enabled is off
because this will kick off automatic triggering before userland is
running, defeating the purpose of the handle_boot_enabled control.
Furthermore, don't ping in case watchdog_set_last_hw_keepalive was
called incorrectly when the hardware watchdog is actually not running.

Fixed: cef9572e9af3 ("watchdog: add support for adjusting last known HW keepalive time")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/93d56386-6e37-060b-55ce-84de8cde535f@web.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: introduce watchdog_dev_suspend/resume

The watchdog drivers often disable wdog clock during suspend and then
enable it again during resume. Nevertheless the ping worker is still
running and

watchdog: introduce watchdog_dev_suspend/resume

The watchdog drivers often disable wdog clock during suspend and then
enable it again during resume. Nevertheless the ping worker is still
running and can issue low-level ping while the wdog clock is disabled
causing the system hang. To prevent such condition register pm notifier
in the watchdog core which will call watchdog_dev_suspend/resume and
actually cancel ping worker during suspend and restore it back, if
needed, during resume.

Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210618195033.3209598-2-grzegorz.jaszczyk@linaro.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Fix NULL pointer dereference when releasing cdev

watchdog_hrtimer_pretimeout_stop needs the watchdog device to have a
valid pointer to the watchdog core data to stop the pretimeout hrtimer

watchdog: Fix NULL pointer dereference when releasing cdev

watchdog_hrtimer_pretimeout_stop needs the watchdog device to have a
valid pointer to the watchdog core data to stop the pretimeout hrtimer.
Therefore it needs to be called before the pointers are cleared in
watchdog_cdev_unregister.

Fixes: 7b7d2fdc8c3e ("watchdog: Add hrtimer-based pretimeout feature")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/1624429583-5720-1-git-send-email-curtis.klein@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: only run driver set_pretimeout op if device supports it

Some watchdog devices might conditionally support pretimeouts (e.g. if
an interrupt is exposed for the device) but some watchdog dri

watchdog: only run driver set_pretimeout op if device supports it

Some watchdog devices might conditionally support pretimeouts (e.g. if
an interrupt is exposed for the device) but some watchdog drivers might
still define the set_pretimeout operation (e.g. the mtk_wdt driver) and
indicate support at runtime through the WDIOF_PRETIMEOUT flag. If the
kernel is compiled with CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT enabled,
watchdog_set_pretimeout would run the driver specific set_pretimeout
even if WDIOF_PRETIMEOUT is not set which might have unintended
consequences.

So this change checks that the device flags and only runs the driver
operation if pretimeouts are supported.

Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/1624751265-24785-1-git-send-email-curtis.klein@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Add hrtimer-based pretimeout feature

This adds the option to use a hrtimer to generate a watchdog pretimeout
event for hardware watchdogs that do not natively support watchdog
pretimeouts.

watchdog: Add hrtimer-based pretimeout feature

This adds the option to use a hrtimer to generate a watchdog pretimeout
event for hardware watchdogs that do not natively support watchdog
pretimeouts.

With this enabled, all watchdogs will appear to have pretimeout support
in userspace. If no pretimeout value is set, there will be no change in
the watchdog's behavior. If a pretimeout value is set for a specific
watchdog that does not have built-in pretimeout support, a timer will be
started that should fire at the specified time before the watchdog
timeout would occur. When the watchdog is successfully pinged, the timer
will be restarted. If the timer is allowed to fire it will generate a
pretimeout event. However because a software timer is used, it may not
be able to fire in every circumstance.

If the watchdog does support a pretimeout natively, that functionality
will be used instead of the hrtimer.

The general design of this feaure was inspired by the software watchdog,
specifically its own pretimeout implementation. However the software
watchdog and this feature are completely independent. They can be used
together; with or without CONFIG_SOFT_WATCHDOG_PRETIMEOUT enabled.

The main advantage of using the hrtimer pretimeout with a hardware
watchdog, compared to running the software watchdog with a hardware
watchdog, is that if the hardware watchdog driver is unable to ping the
watchdog (e.g. due to a bus or communication error), then the hrtimer
pretimeout would still fire whereas the software watchdog would not.

Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/1612383090-27110-1-git-send-email-curtis.klein@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Use sysfs_emit() and sysfs_emit_at() in "show" functions

Convert sprintf() in sysfs "show" functions to sysfs_emit() and
sysfs_emit_at() in order to check for buffer overruns in sysfs outp

watchdog: Use sysfs_emit() and sysfs_emit_at() in "show" functions

Convert sprintf() in sysfs "show" functions to sysfs_emit() and
sysfs_emit_at() in order to check for buffer overruns in sysfs outputs.

Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210511061812.480172-1-juergh@canonical.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Add {min,max}_timeout sysfs nodes

The valid range for the 'timeout' value is useful information so expose
the min and max timeout values via sysfs.

Signed-off-by: Juerg Haefliger <juergh@

watchdog: Add {min,max}_timeout sysfs nodes

The valid range for the 'timeout' value is useful information so expose
the min and max timeout values via sysfs.

Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210511062953.485252-1-juergh@canonical.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: remove unneeded inclusion of <uapi/linux/sched/types.h>

There has been no reference to "struct sched_param" since
commit 94beddacb53c ("sched,watchdog: Convert to sched_set_fifo()"), so
th

watchdog: remove unneeded inclusion of <uapi/linux/sched/types.h>

There has been no reference to "struct sched_param" since
commit 94beddacb53c ("sched,watchdog: Convert to sched_set_fifo()"), so
there's no need to include <uapi/linux/sched/types.h> any more, delete
it.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200827062154.1847-1-thunder.leizhen@huawei.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Use put_device on error

We should use put_device() instead of freeing device
directly after device_initialize().

Fixes: cb36e29bb0e4b ("watchdog: initialize device before misc_register")

watchdog: Use put_device on error

We should use put_device() instead of freeing device
directly after device_initialize().

Fixes: cb36e29bb0e4b ("watchdog: initialize device before misc_register")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200824031230.31050-1-dinghao.liu@zju.edu.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Fix memleak in watchdog_cdev_register

When watchdog_kworker is NULL, we should free wd_data
before the function returns to prevent memleak.

Fixes: 664a39236e718 ("watchdog: Introduce hard

watchdog: Fix memleak in watchdog_cdev_register

When watchdog_kworker is NULL, we should free wd_data
before the function returns to prevent memleak.

Fixes: 664a39236e718 ("watchdog: Introduce hardware maximum heartbeat in watchdog core")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200824024001.25474-1-dinghao.liu@zju.edu.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: add support for adjusting last known HW keepalive time

Certain watchdogs require the watchdog only to be pinged within a
specific time window, pinging too early or too late cause the watch

watchdog: add support for adjusting last known HW keepalive time

Certain watchdogs require the watchdog only to be pinged within a
specific time window, pinging too early or too late cause the watchdog
to fire. In cases where this sort of watchdog has been started before
kernel comes up, we must adjust the watchdog keepalive window to match
the actually running timer, so add a new driver API for this purpose.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200717132958.14304-3-t-kristo@ti.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: use __watchdog_ping in startup

Current watchdog startup functionality does not respect the minimum hw
heartbeat setup and the last watchdog ping timeframe when watchdog is
already running

watchdog: use __watchdog_ping in startup

Current watchdog startup functionality does not respect the minimum hw
heartbeat setup and the last watchdog ping timeframe when watchdog is
already running and userspace process attaches to it. Fix this by using
the __watchdog_ping from the startup also. For this code path, we can
also let the __watchdog_ping handle the bookkeeping for the worker and
last keepalive times.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200717132958.14304-2-t-kristo@ti.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: initialize device before misc_register

When watchdog device is being registered, it calls misc_register that
makes watchdog available for systemd to open. This is a data race
scenario, bec

watchdog: initialize device before misc_register

When watchdog device is being registered, it calls misc_register that
makes watchdog available for systemd to open. This is a data race
scenario, because when device is open it may still have device struct
not initialized - this in turn causes a crash. This patch moves
device initialization before misc_register call and it solves the
problem printed below.

------------[ cut here ]------------
WARNING: CPU: 3 PID: 1 at lib/kobject.c:612 kobject_get+0x50/0x54
kobject: '(null)' ((ptrval)): is not initialized, yet kobject_get() is being called.
Modules linked in: k2_reset_status(O) davinci_wdt(+) sfn_platform_hwbcn(O) fsmddg_sfn(O) clk_misc_mmap(O) clk_sw_bcn(O) fsp_reset(O) cma_mod(O) slave_sup_notif(O) fpga_master(O) latency(O+) evnotify(O) enable_arm_pmu(O) xge(O) rio_mport_cdev br_netfilter bridge stp llc nvrd_checksum(O) ipv6
CPU: 3 PID: 1 Comm: systemd Tainted: G O 4.19.113-g2579778-fsm4_k2 #1
Hardware name: Keystone
[<c02126c4>] (unwind_backtrace) from [<c020da94>] (show_stack+0x18/0x1c)
[<c020da94>] (show_stack) from [<c07f87d8>] (dump_stack+0xb4/0xe8)
[<c07f87d8>] (dump_stack) from [<c0221f70>] (__warn+0xfc/0x114)
[<c0221f70>] (__warn) from [<c0221fd8>] (warn_slowpath_fmt+0x50/0x74)
[<c0221fd8>] (warn_slowpath_fmt) from [<c07fd394>] (kobject_get+0x50/0x54)
[<c07fd394>] (kobject_get) from [<c0602ce8>] (get_device+0x1c/0x24)
[<c0602ce8>] (get_device) from [<c06961e0>] (watchdog_open+0x90/0xf0)
[<c06961e0>] (watchdog_open) from [<c06001dc>] (misc_open+0x130/0x17c)
[<c06001dc>] (misc_open) from [<c0388228>] (chrdev_open+0xec/0x1a8)
[<c0388228>] (chrdev_open) from [<c037fa98>] (do_dentry_open+0x204/0x3cc)
[<c037fa98>] (do_dentry_open) from [<c0391e2c>] (path_openat+0x330/0x1148)
[<c0391e2c>] (path_openat) from [<c0394518>] (do_filp_open+0x78/0xec)
[<c0394518>] (do_filp_open) from [<c0381100>] (do_sys_open+0x130/0x1f4)
[<c0381100>] (do_sys_open) from [<c0201000>] (ret_fast_syscall+0x0/0x28)
Exception stack(0xd2ceffa8 to 0xd2cefff0)
ffa0: b6f69968 00000000 ffffff9c b6ebd210 000a0001 00000000
ffc0: b6f69968 00000000 00000000 00000142 fffffffd ffffffff 00b65530 bed7bb78
ffe0: 00000142 bed7ba70 b6cc2503 b6cc41d6
---[ end trace 7b16eb105513974f ]---

------------[ cut here ]------------
WARNING: CPU: 3 PID: 1 at lib/refcount.c:153 kobject_get+0x24/0x54
refcount_t: increment on 0; use-after-free.
Modules linked in: k2_reset_status(O) davinci_wdt(+) sfn_platform_hwbcn(O) fsmddg_sfn(O) clk_misc_mmap(O) clk_sw_bcn(O) fsp_reset(O) cma_mod(O) slave_sup_notif(O) fpga_master(O) latency(O+) evnotify(O) enable_arm_pmu(O) xge(O) rio_mport_cdev br_netfilter bridge stp llc nvrd_checksum(O) ipv6
CPU: 3 PID: 1 Comm: systemd Tainted: G W O 4.19.113-g2579778-fsm4_k2 #1
Hardware name: Keystone
[<c02126c4>] (unwind_backtrace) from [<c020da94>] (show_stack+0x18/0x1c)
[<c020da94>] (show_stack) from [<c07f87d8>] (dump_stack+0xb4/0xe8)
[<c07f87d8>] (dump_stack) from [<c0221f70>] (__warn+0xfc/0x114)
[<c0221f70>] (__warn) from [<c0221fd8>] (warn_slowpath_fmt+0x50/0x74)
[<c0221fd8>] (warn_slowpath_fmt) from [<c07fd368>] (kobject_get+0x24/0x54)
[<c07fd368>] (kobject_get) from [<c0602ce8>] (get_device+0x1c/0x24)
[<c0602ce8>] (get_device) from [<c06961e0>] (watchdog_open+0x90/0xf0)
[<c06961e0>] (watchdog_open) from [<c06001dc>] (misc_open+0x130/0x17c)
[<c06001dc>] (misc_open) from [<c0388228>] (chrdev_open+0xec/0x1a8)
[<c0388228>] (chrdev_open) from [<c037fa98>] (do_dentry_open+0x204/0x3cc)
[<c037fa98>] (do_dentry_open) from [<c0391e2c>] (path_openat+0x330/0x1148)
[<c0391e2c>] (path_openat) from [<c0394518>] (do_filp_open+0x78/0xec)
[<c0394518>] (do_filp_open) from [<c0381100>] (do_sys_open+0x130/0x1f4)
[<c0381100>] (do_sys_open) from [<c0201000>] (ret_fast_syscall+0x0/0x28)
Exception stack(0xd2ceffa8 to 0xd2cefff0)
ffa0: b6f69968 00000000 ffffff9c b6ebd210 000a0001 00000000
ffc0: b6f69968 00000000 00000000 00000142 fffffffd ffffffff 00b65530 bed7bb78
ffe0: 00000142 bed7ba70 b6cc2503 b6cc41d6
---[ end trace 7b16eb1055139750 ]---

Fixes: 72139dfa2464 ("watchdog: Fix the race between the release of watchdog_core_data and cdev")
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Krzysztof Sobota <krzysztof.sobota@nokia.com>
Link: https://lore.kernel.org/r/20200717103109.14660-1-krzysztof.sobota@nokia.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through mar

watchdog: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200707171121.GA13472@embeddedor
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...

watchdog: Use kobj_to_dev() API

Use kobj_to_dev() API instead of container_of().

Signed-off-by: Wang Qing <wangqing@vivo.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kern

watchdog: Use kobj_to_dev() API

Use kobj_to_dev() API instead of container_of().

Signed-off-by: Wang Qing <wangqing@vivo.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/1591945384-14587-1-git-send-email-wangqing@vivo.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

show more ...