From 60bcd91aafd22ef62cef9ae2037fa2e1d4da2fb3 Mon Sep 17 00:00:00 2001 From: Grzegorz Jaszczyk Date: Fri, 18 Jun 2021 21:50:32 +0200 Subject: [PATCH] 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 Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20210618195033.3209598-2-grzegorz.jaszczyk@linaro.org Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/watchdog_core.c | 37 +++++++++++++++++++++++++ drivers/watchdog/watchdog_dev.c | 47 ++++++++++++++++++++++++++++++++ include/linux/watchdog.h | 10 +++++++ 3 files changed, 94 insertions(+) diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c index 5df0a22e2cb4..3fe8a7edc252 100644 --- a/drivers/watchdog/watchdog_core.c +++ b/drivers/watchdog/watchdog_core.c @@ -34,6 +34,7 @@ #include /* For ida_* macros */ #include /* For IS_ERR macros */ #include /* For of_get_timeout_sec */ +#include #include "watchdog_core.h" /* For watchdog_dev_register/... */ @@ -185,6 +186,33 @@ static int watchdog_restart_notifier(struct notifier_block *nb, return NOTIFY_DONE; } +static int watchdog_pm_notifier(struct notifier_block *nb, unsigned long mode, + void *data) +{ + struct watchdog_device *wdd; + int ret = 0; + + wdd = container_of(nb, struct watchdog_device, pm_nb); + + switch (mode) { + case PM_HIBERNATION_PREPARE: + case PM_RESTORE_PREPARE: + case PM_SUSPEND_PREPARE: + ret = watchdog_dev_suspend(wdd); + break; + case PM_POST_HIBERNATION: + case PM_POST_RESTORE: + case PM_POST_SUSPEND: + ret = watchdog_dev_resume(wdd); + break; + } + + if (ret) + return NOTIFY_BAD; + + return NOTIFY_DONE; +} + /** * watchdog_set_restart_priority - Change priority of restart handler * @wdd: watchdog device @@ -292,6 +320,15 @@ static int __watchdog_register_device(struct watchdog_device *wdd) wdd->id, ret); } + if (test_bit(WDOG_NO_PING_ON_SUSPEND, &wdd->status)) { + wdd->pm_nb.notifier_call = watchdog_pm_notifier; + + ret = register_pm_notifier(&wdd->pm_nb); + if (ret) + pr_warn("watchdog%d: Cannot register pm handler (%d)\n", + wdd->id, ret); + } + return 0; } diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index f408967ff1a4..597cf16ea4ba 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -1228,6 +1228,53 @@ void __exit watchdog_dev_exit(void) kthread_destroy_worker(watchdog_kworker); } +int watchdog_dev_suspend(struct watchdog_device *wdd) +{ + struct watchdog_core_data *wd_data = wdd->wd_data; + int ret = 0; + + if (!wdd->wd_data) + return -ENODEV; + + /* ping for the last time before suspend */ + mutex_lock(&wd_data->lock); + if (watchdog_worker_should_ping(wd_data)) + ret = __watchdog_ping(wd_data->wdd); + mutex_unlock(&wd_data->lock); + + if (ret) + return ret; + + /* + * make sure that watchdog worker will not kick in when the wdog is + * suspended + */ + hrtimer_cancel(&wd_data->timer); + kthread_cancel_work_sync(&wd_data->work); + + return 0; +} + +int watchdog_dev_resume(struct watchdog_device *wdd) +{ + struct watchdog_core_data *wd_data = wdd->wd_data; + int ret = 0; + + if (!wdd->wd_data) + return -ENODEV; + + /* + * __watchdog_ping will also retrigger hrtimer and therefore restore the + * ping worker if needed. + */ + mutex_lock(&wd_data->lock); + if (watchdog_worker_should_ping(wd_data)) + ret = __watchdog_ping(wd_data->wdd); + mutex_unlock(&wd_data->lock); + + return ret; +} + module_param(handle_boot_enabled, bool, 0444); MODULE_PARM_DESC(handle_boot_enabled, "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h index 9b19e6bb68b5..99660197a36c 100644 --- a/include/linux/watchdog.h +++ b/include/linux/watchdog.h @@ -107,6 +107,7 @@ struct watchdog_device { unsigned int max_hw_heartbeat_ms; struct notifier_block reboot_nb; struct notifier_block restart_nb; + struct notifier_block pm_nb; void *driver_data; struct watchdog_core_data *wd_data; unsigned long status; @@ -116,6 +117,7 @@ struct watchdog_device { #define WDOG_STOP_ON_REBOOT 2 /* Should be stopped on reboot */ #define WDOG_HW_RUNNING 3 /* True if HW watchdog running */ #define WDOG_STOP_ON_UNREGISTER 4 /* Should be stopped on unregister */ +#define WDOG_NO_PING_ON_SUSPEND 5 /* Ping worker should be stopped on suspend */ struct list_head deferred; }; @@ -156,6 +158,12 @@ static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd) set_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status); } +/* Use the following function to stop the wdog ping worker when suspending */ +static inline void watchdog_stop_ping_on_suspend(struct watchdog_device *wdd) +{ + set_bit(WDOG_NO_PING_ON_SUSPEND, &wdd->status); +} + /* Use the following function to check if a timeout value is invalid */ static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t) { @@ -209,6 +217,8 @@ extern int watchdog_init_timeout(struct watchdog_device *wdd, unsigned int timeout_parm, struct device *dev); extern int watchdog_register_device(struct watchdog_device *); extern void watchdog_unregister_device(struct watchdog_device *); +int watchdog_dev_suspend(struct watchdog_device *wdd); +int watchdog_dev_resume(struct watchdog_device *wdd); int watchdog_set_last_hw_keepalive(struct watchdog_device *, unsigned int);