86 lines
2.8 KiB
Diff
86 lines
2.8 KiB
Diff
From 0e8d6a9336b487a1dd6f1991ff376e669d4c87c6 Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Wed, 12 Apr 2017 22:07:28 +0200
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Subject: [PATCH 02/13] workqueue: Provide work_on_cpu_safe()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.11/older/patches-4.11.5-rt1.tar.xz
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work_on_cpu() is not protected against CPU hotplug. For code which requires
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to be either executed on an online CPU or to fail if the CPU is not
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available the callsite would have to protect against CPU hotplug.
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Provide a function which does get/put_online_cpus() around the call to
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work_on_cpu() and fails the call with -ENODEV if the target CPU is not
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online.
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Preparatory patch to convert several racy task affinity manipulations.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Acked-by: Tejun Heo <tj@kernel.org>
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Cc: Fenghua Yu <fenghua.yu@intel.com>
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Cc: Tony Luck <tony.luck@intel.com>
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Cc: Herbert Xu <herbert@gondor.apana.org.au>
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Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Cc: Sebastian Siewior <bigeasy@linutronix.de>
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Cc: Lai Jiangshan <jiangshanlai@gmail.com>
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Cc: Viresh Kumar <viresh.kumar@linaro.org>
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Cc: Michael Ellerman <mpe@ellerman.id.au>
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Cc: "David S. Miller" <davem@davemloft.net>
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Cc: Len Brown <lenb@kernel.org>
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Link: http://lkml.kernel.org/r/20170412201042.262610721@linutronix.de
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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include/linux/workqueue.h | 5 +++++
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kernel/workqueue.c | 23 +++++++++++++++++++++++
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2 files changed, 28 insertions(+)
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--- a/include/linux/workqueue.h
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+++ b/include/linux/workqueue.h
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@@ -608,8 +608,13 @@ static inline long work_on_cpu(int cpu,
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{
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return fn(arg);
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}
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+static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
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+{
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+ return fn(arg);
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+}
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#else
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long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
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+long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
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#endif /* CONFIG_SMP */
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#ifdef CONFIG_FREEZER
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--- a/kernel/workqueue.c
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+++ b/kernel/workqueue.c
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@@ -4735,6 +4735,29 @@ long work_on_cpu(int cpu, long (*fn)(voi
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return wfc.ret;
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}
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EXPORT_SYMBOL_GPL(work_on_cpu);
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+
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+/**
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+ * work_on_cpu_safe - run a function in thread context on a particular cpu
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+ * @cpu: the cpu to run on
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+ * @fn: the function to run
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+ * @arg: the function argument
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+ *
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+ * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
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+ * any locks which would prevent @fn from completing.
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+ *
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+ * Return: The value @fn returns.
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+ */
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+long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
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+{
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+ long ret = -ENODEV;
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+
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+ get_online_cpus();
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+ if (cpu_online(cpu))
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+ ret = work_on_cpu(cpu, fn, arg);
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+ put_online_cpus();
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(work_on_cpu_safe);
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#endif /* CONFIG_SMP */
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#ifdef CONFIG_FREEZER
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