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authorThomas Gleixner <tglx@linutronix.de>2017-04-12 22:07:28 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-04-15 12:20:53 +0200
commit0e8d6a9336b487a1dd6f1991ff376e669d4c87c6 (patch)
tree11bf45da14998976aeb13623f52673b64af35177
parentia64/topology: Remove cpus_allowed manipulation (diff)
downloadlinux-0e8d6a9336b487a1dd6f1991ff376e669d4c87c6.tar.xz
linux-0e8d6a9336b487a1dd6f1991ff376e669d4c87c6.zip
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 <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>
-rw-r--r--include/linux/workqueue.h5
-rw-r--r--kernel/workqueue.c23
2 files changed, 28 insertions, 0 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index bde063cefd04..c102ef65cb64 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -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
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