From 0e8d6a9336b487a1dd6f1991ff376e669d4c87c6 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 12 Apr 2017 22:07:28 +0200 Subject: workqueue: Provide work_on_cpu_safe() 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 Acked-by: Tejun Heo Cc: Fenghua Yu Cc: Tony Luck Cc: Herbert Xu Cc: "Rafael J. Wysocki" Cc: Peter Zijlstra Cc: Benjamin Herrenschmidt Cc: Sebastian Siewior Cc: Lai Jiangshan Cc: Viresh Kumar Cc: Michael Ellerman Cc: "David S. Miller" Cc: Len Brown Link: http://lkml.kernel.org/r/20170412201042.262610721@linutronix.de Signed-off-by: Thomas Gleixner --- kernel/workqueue.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'kernel/workqueue.c') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index c0168b7da1ea..5bf1be018628 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -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 -- cgit