diff options
| -rw-r--r-- | include/linux/nmi.h | 2 | ||||
| -rw-r--r-- | kernel/watchdog.c | 65 |
2 files changed, 67 insertions, 0 deletions
diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 088714537d10..e9f213c337bb 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -82,6 +82,8 @@ extern int proc_watchdog_thresh(struct ctl_table *, int , void __user *, size_t *, loff_t *); extern int proc_watchdog_cpumask(struct ctl_table *, int, void __user *, size_t *, loff_t *); +extern int watchdog_suspend(void); +extern void watchdog_resume(void); #endif #ifdef CONFIG_HAVE_ACPI_APEI_NMI diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 6c489e49c610..e6eb5b697212 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -67,6 +67,7 @@ unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); #define for_each_watchdog_cpu(cpu) \ for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask) +static int __read_mostly watchdog_suspended; static int __read_mostly watchdog_running; static u64 __read_mostly sample_period; @@ -700,6 +701,50 @@ static void watchdog_unpark_threads(void) put_online_cpus(); } +/* + * Suspend the hard and soft lockup detector by parking the watchdog threads. + */ +int watchdog_suspend(void) +{ + int ret = 0; + + mutex_lock(&watchdog_proc_mutex); + /* + * Multiple suspend requests can be active in parallel (counted by + * the 'watchdog_suspended' variable). If the watchdog threads are + * running, the first caller takes care that they will be parked. + * The state of 'watchdog_running' cannot change while a suspend + * request is active (see related changes in 'proc' handlers). + */ + if (watchdog_running && !watchdog_suspended) + ret = watchdog_park_threads(); + + if (ret == 0) + watchdog_suspended++; + + mutex_unlock(&watchdog_proc_mutex); + + return ret; +} + +/* + * Resume the hard and soft lockup detector by unparking the watchdog threads. + */ +void watchdog_resume(void) +{ + mutex_lock(&watchdog_proc_mutex); + + watchdog_suspended--; + /* + * The watchdog threads are unparked if they were previously running + * and if there is no more active suspend request. + */ + if (watchdog_running && !watchdog_suspended) + watchdog_unpark_threads(); + + mutex_unlock(&watchdog_proc_mutex); +} + static void restart_watchdog_hrtimer(void *info) { struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); @@ -818,6 +863,12 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write, mutex_lock(&watchdog_proc_mutex); + if (watchdog_suspended) { + /* no parameter changes allowed while watchdog is suspended */ + err = -EAGAIN; + goto out; + } + /* * If the parameter is being read return the state of the corresponding * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the @@ -903,6 +954,12 @@ int proc_watchdog_thresh(struct ctl_table *table, int write, mutex_lock(&watchdog_proc_mutex); + if (watchdog_suspended) { + /* no parameter changes allowed while watchdog is suspended */ + err = -EAGAIN; + goto out; + } + old = ACCESS_ONCE(watchdog_thresh); err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); @@ -934,6 +991,13 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write, int err; mutex_lock(&watchdog_proc_mutex); + + if (watchdog_suspended) { + /* no parameter changes allowed while watchdog is suspended */ + err = -EAGAIN; + goto out; + } + err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); if (!err && write) { /* Remove impossible cpus to keep sysctl output cleaner. */ @@ -951,6 +1015,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write, pr_err("cpumask update failed\n"); } } +out: mutex_unlock(&watchdog_proc_mutex); return err; } |