workqueue: Provide work_on_cpu_safe() (0e8d6a93) · Commits · 戴 / test

work_on_cpu() is not protected against CPU hotplug. For code which requires to be either executed on an online CPU or to fail if the CPU is not available the callsite would have to protect against CPU hotplug. Provide a function which does get/put_online_cpus() around the call to work_on_cpu() and fails the call with -ENODEV if the target CPU is not online. Preparatory patch to convert several racy task affinity manipulations. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Acked-by:

Tejun Heo <tj@kernel.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Len Brown <lenb@kernel.org> Link: http://lkml.kernel.org/r/20170412201042.262610721@linutronix.de Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

include/linux/workqueue.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -608,8 +608,13 @@ static inline long work_on_cpu(int cpu, long (fn)(void ), void *arg)
		{
		return fn(arg);
		}
		static inline long work_on_cpu_safe(int cpu, long (fn)(void ), void *arg)
		{
		return fn(arg);
		}
		#else
		long work_on_cpu(int cpu, long (fn)(void ), void *arg);
		long work_on_cpu_safe(int cpu, long (fn)(void ), void *arg);
		#endif /* CONFIG_SMP */

		#ifdef CONFIG_FREEZER

kernel/workqueue.c

+23 −0

Original line number	Diff line number	Diff line
		@@ -4735,6 +4735,29 @@ long work_on_cpu(int cpu, long (fn)(void ), void *arg)
		return wfc.ret;
		}
		EXPORT_SYMBOL_GPL(work_on_cpu);

		/**
		* work_on_cpu_safe - run a function in thread context on a particular cpu
		* @cpu: the cpu to run on
		* @fn: the function to run
		* @arg: the function argument
		*
		* Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
		* any locks which would prevent @fn from completing.
		*
		* Return: The value @fn returns.
		*/
		long work_on_cpu_safe(int cpu, long (fn)(void ), void *arg)
		{
		long ret = -ENODEV;

		get_online_cpus();
		if (cpu_online(cpu))
		ret = work_on_cpu(cpu, fn, arg);
		put_online_cpus();
		return ret;
		}
		EXPORT_SYMBOL_GPL(work_on_cpu_safe);
		#endif /* CONFIG_SMP */

		#ifdef CONFIG_FREEZER

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