From 5490125d77a43016b26f629d4b485e2c62172551 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 12 Sep 2017 21:36:59 +0200 Subject: watchdog/core: Remove broken suspend/resume interfaces This interface has several issues: - It's causing recursive locking of the hotplug lock. - It's complete overkill to teardown all threads and then recreate them The same can be achieved with the simple hardlockup_detector_perf_stop / restart() interfaces. The abuse from the busy looping poweroff() loop of PARISC has been solved as well. Remove the cruft. Signed-off-by: Thomas Gleixner Reviewed-by: Don Zickus Cc: Andrew Morton Cc: Borislav Petkov Cc: Chris Metcalf Cc: Linus Torvalds Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Sebastian Siewior Cc: Ulrich Obergfell Link: http://lkml.kernel.org/r/20170912194146.487537732@linutronix.de Signed-off-by: Ingo Molnar --- kernel/watchdog.c | 89 +------------------------------------------------------ 1 file changed, 1 insertion(+), 88 deletions(-) (limited to 'kernel/watchdog.c') diff --git a/kernel/watchdog.c b/kernel/watchdog.c index f23e373aa3bf..b2d46757917e 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -97,19 +97,6 @@ unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); * unregistered/stopped, so it is an indicator whether the threads exist. */ static int __read_mostly watchdog_running; -/* - * If a subsystem has a need to deactivate the watchdog temporarily, it - * can use the suspend/resume interface to achieve this. The content of - * the 'watchdog_suspended' variable reflects this state. Existing threads - * are parked/unparked by the lockup_detector_{suspend|resume} functions - * (see comment blocks pertaining to those functions for further details). - * - * 'watchdog_suspended' also prevents threads from being registered/started - * or unregistered/stopped via parameters in /proc/sys/kernel, so the state - * of 'watchdog_running' cannot change while the watchdog is deactivated - * temporarily (see related code in 'proc' handlers). - */ -int __read_mostly watchdog_suspended; /* * These functions can be overridden if an architecture implements its @@ -136,7 +123,6 @@ void __weak watchdog_nmi_disable(unsigned int cpu) * - watchdog_cpumask * - sysctl_hardlockup_all_cpu_backtrace * - hardlockup_panic - * - watchdog_suspended */ void __weak watchdog_nmi_reconfigure(void) { @@ -672,61 +658,6 @@ void lockup_detector_soft_poweroff(void) watchdog_enabled = 0; } -/* - * Suspend the hard and soft lockup detector by parking the watchdog threads. - */ -int lockup_detector_suspend(void) -{ - int ret = 0; - - get_online_cpus(); - 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 code in 'proc' handlers). - */ - if (watchdog_running && !watchdog_suspended) - ret = watchdog_park_threads(); - - if (ret == 0) - watchdog_suspended++; - else { - watchdog_disable_all_cpus(); - pr_err("Failed to suspend lockup detectors, disabled\n"); - watchdog_enabled = 0; - } - - watchdog_nmi_reconfigure(); - - mutex_unlock(&watchdog_proc_mutex); - - return ret; -} - -/* - * Resume the hard and soft lockup detector by unparking the watchdog threads. - */ -void lockup_detector_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(); - - watchdog_nmi_reconfigure(); - - mutex_unlock(&watchdog_proc_mutex); - put_online_cpus(); -} - #ifdef CONFIG_SYSCTL /* @@ -775,12 +706,6 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write, get_online_cpus(); 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 @@ -872,12 +797,6 @@ int proc_watchdog_thresh(struct ctl_table *table, int write, get_online_cpus(); 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); @@ -917,12 +836,6 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write, get_online_cpus(); 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. */ @@ -941,7 +854,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write, watchdog_nmi_reconfigure(); } -out: + mutex_unlock(&watchdog_proc_mutex); put_online_cpus(); return err; -- cgit v1.2.3