watchdog: Fix merge 'conflict' (ab992dc3) · Commits · 戴 / test

Two watchdog changes that came through different trees had a non conflicting conflict, that is, one changed the semantics of a variable but no actual code conflict happened. So the merge appeared fine, but the resulting code did not behave as expected. Commit ("watchdog: enable the new user interface of the watchdog mechanism") changes the semantics of watchdog_user_enabled, which thereafter is only used by the functions introduced by ("watchdog: Add watchdog enable/disable all functions"). There further appears to be a distinct lack of serialization between setting and using watchdog_enabled, so perhaps we should wrap the {en,dis}able_all() things in watchdog_proc_mutex. This patch fixes a s2r failure reported by Michal; which I cannot readily explain. But this does make the code internally consistent again. Reported-and-tested-by:

Michal Hocko <mhocko@suse.cz> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

kernel/watchdog.c

+15 −5

Original line number	Diff line number	Diff line
		@@ -41,6 +41,8 @@
		#define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT)
		#define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT)

		static DEFINE_MUTEX(watchdog_proc_mutex);

		#ifdef CONFIG_HARDLOCKUP_DETECTOR
		static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED\|NMI_WATCHDOG_ENABLED;
		#else
		@@ -608,26 +610,36 @@ void watchdog_nmi_enable_all(void)
		{
		int cpu;

		if (!watchdog_user_enabled)
		return;
		mutex_lock(&watchdog_proc_mutex);

		if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
		goto unlock;

		get_online_cpus();
		for_each_online_cpu(cpu)
		watchdog_nmi_enable(cpu);
		put_online_cpus();

		unlock:
		mutex_lock(&watchdog_proc_mutex);
		}

		void watchdog_nmi_disable_all(void)
		{
		int cpu;

		mutex_lock(&watchdog_proc_mutex);

		if (!watchdog_running)
		return;
		goto unlock;

		get_online_cpus();
		for_each_online_cpu(cpu)
		watchdog_nmi_disable(cpu);
		put_online_cpus();

		unlock:
		mutex_unlock(&watchdog_proc_mutex);
		}
		#else
		static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
		@@ -744,8 +756,6 @@ static int proc_watchdog_update(void)

		}

		static DEFINE_MUTEX(watchdog_proc_mutex);

		/*
		* common function for watchdog, nmi_watchdog and soft_watchdog parameter
		*

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