54 lines
1.5 KiB
Diff
54 lines
1.5 KiB
Diff
From: Tiejun Chen <tiejun.chen@windriver.com>
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Subject: cpu_down: move migrate_enable() back
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Date: Thu, 7 Nov 2013 10:06:07 +0800
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.4/patches-4.4.1-rt6.tar.xz
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Commit 08c1ab68, "hotplug-use-migrate-disable.patch", intends to
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use migrate_enable()/migrate_disable() to replace that combination
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of preempt_enable() and preempt_disable(), but actually in
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!CONFIG_PREEMPT_RT_FULL case, migrate_enable()/migrate_disable()
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are still equal to preempt_enable()/preempt_disable(). So that
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followed cpu_hotplug_begin()/cpu_unplug_begin(cpu) would go schedule()
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to trigger schedule_debug() like this:
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_cpu_down()
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+ migrate_disable() = preempt_disable()
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+ cpu_hotplug_begin() or cpu_unplug_begin()
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+ schedule()
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+ __schedule()
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+ preempt_disable();
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+ __schedule_bug() is true!
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So we should move migrate_enable() as the original scheme.
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Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
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---
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kernel/cpu.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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--- a/kernel/cpu.c
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+++ b/kernel/cpu.c
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@@ -657,6 +657,7 @@ static int _cpu_down(unsigned int cpu, i
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err = -EBUSY;
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goto restore_cpus;
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}
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+ migrate_enable();
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cpu_hotplug_begin();
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err = cpu_unplug_begin(cpu);
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@@ -741,7 +742,6 @@ static int _cpu_down(unsigned int cpu, i
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out_release:
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cpu_unplug_done(cpu);
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out_cancel:
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- migrate_enable();
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cpu_hotplug_done();
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if (!err)
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cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
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