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Revision a0cff57bb2a41cb9cbf13d3203097b4156d8c0ae authored by Davidlohr Bueso on 13 September 2017, 20:08:21 UTC, committed by Paolo Bonzini on 15 September 2017, 14:57:12 UTC 
kvm,x86: Fix apf_task_wake_one() wq serialization
 
During code inspection, the following potential race was seen:

CPU0   	    		    	     	CPU1
kvm_async_pf_task_wait			apf_task_wake_one
					  [L] swait_active(&n->wq)
  [S] prepare_to_swait(&n.wq)
  [L] if (!hlist_unhahed(&n.link))
	schedule()			  [S] hlist_del_init(&n->link);

Properly serialize swait_active() checks such that a wakeup is
not missed.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent cc1b468
Raw File
simple-pm-bus.c 
/*
 * Simple Power-Managed Bus Driver
 *
 * Copyright (C) 2014-2015 Glider bvba
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>


static int simple_pm_bus_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;

	dev_dbg(&pdev->dev, "%s\n", __func__);

	pm_runtime_enable(&pdev->dev);

	if (np)
		of_platform_populate(np, NULL, NULL, &pdev->dev);

	return 0;
}

static int simple_pm_bus_remove(struct platform_device *pdev)
{
	dev_dbg(&pdev->dev, "%s\n", __func__);

	pm_runtime_disable(&pdev->dev);
	return 0;
}

static const struct of_device_id simple_pm_bus_of_match[] = {
	{ .compatible = "simple-pm-bus", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, simple_pm_bus_of_match);

static struct platform_driver simple_pm_bus_driver = {
	.probe = simple_pm_bus_probe,
	.remove = simple_pm_bus_remove,
	.driver = {
		.name = "simple-pm-bus",
		.of_match_table = simple_pm_bus_of_match,
	},
};

module_platform_driver(simple_pm_bus_driver);

MODULE_DESCRIPTION("Simple Power-Managed Bus Driver");
MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
MODULE_LICENSE("GPL v2");
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