kernel/drivers/watchdog/watchdog_dev.c, branch linux-5.1.y

watchdog: core: fix null pointer dereference when releasing cdev

2018-10-02T11:32:24Z

watchdog_stop() calls watchdog_update_worker() which needs a valid wdd->wd_data pointer. So, when unregistering the cdev, clear the pointers after we call watchdog_stop(), not before. Fixes: bb292ac1c602 ("watchdog: Introduce watchdog_stop_on_unregister helper") Signed-off-by: Wolfram Sang Reviewed-by: Fabrizio Castro Reviewed-by: Guenter Roeck Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck

watchdog: core: make sure the watchdog_worker is not deferred

2018-01-21T11:44:59Z

commit 4cd13c21b207e ("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 Reviewed-by: Guenter Roeck Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck

watchdog: core: make sure the watchdog worker always works

2017-12-28T19:45:57Z

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

watchdog: watchdog_dev: mark expected switch fall-through

2017-12-28T19:45:30Z

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

watchdog: Fix kref imbalance seen if handle_boot_enabled=0

2017-12-17T10:01:48Z

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: 2501b015313fe ("watchdog: core: add option to avoid early ...") Cc: Sebastian Reichel Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck

watchdog: Fix potential kref imbalance when opening watchdog

2017-12-17T10:01:47Z

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: ee142889e32f5 ("watchdog: Introduce WDOG_HW_RUNNING flag") Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck

drivers/watchdog: make use of devm_register_reboot_notifier()

2017-11-18T00:10:04Z

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 Acked-by: Guenter Roeck Cc: Chris Healy Cc: Wim Van Sebroeck Cc: Andy Shevchenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

watchdog: introduce watchdog_worker_should_ping helper

2017-07-03T11:59:05Z

This will be useful when the condition becomes slightly more complicated in the next patch. Signed-off-by: Rasmus Villemoes Reviewed-by: Esben Haabendal Reviewed-by: Guenter Roeck Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck

watchdog: core: add option to avoid early handling of watchdog

2017-06-05T18:55:17Z

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

watchdog: Introduce watchdog_stop_on_unregister helper

2017-02-24T22:00:23Z

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