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
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
rtc-sun4v.c
/* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems.
*
* Author: David S. Miller
* License: GPL
*
* Copyright (C) 2008 David S. Miller <davem@davemloft.net>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <asm/hypervisor.h>
static unsigned long hypervisor_get_time(void)
{
unsigned long ret, time;
int retries = 10000;
retry:
ret = sun4v_tod_get(&time);
if (ret == HV_EOK)
return time;
if (ret == HV_EWOULDBLOCK) {
if (--retries > 0) {
udelay(100);
goto retry;
}
pr_warn("tod_get() timed out.\n");
return 0;
}
pr_warn("tod_get() not supported.\n");
return 0;
}
static int sun4v_read_time(struct device *dev, struct rtc_time *tm)
{
rtc_time_to_tm(hypervisor_get_time(), tm);
return 0;
}
static int hypervisor_set_time(unsigned long secs)
{
unsigned long ret;
int retries = 10000;
retry:
ret = sun4v_tod_set(secs);
if (ret == HV_EOK)
return 0;
if (ret == HV_EWOULDBLOCK) {
if (--retries > 0) {
udelay(100);
goto retry;
}
pr_warn("tod_set() timed out.\n");
return -EAGAIN;
}
pr_warn("tod_set() not supported.\n");
return -EOPNOTSUPP;
}
static int sun4v_set_time(struct device *dev, struct rtc_time *tm)
{
unsigned long secs;
int err;
err = rtc_tm_to_time(tm, &secs);
if (err)
return err;
return hypervisor_set_time(secs);
}
static const struct rtc_class_ops sun4v_rtc_ops = {
.read_time = sun4v_read_time,
.set_time = sun4v_set_time,
};
static int __init sun4v_rtc_probe(struct platform_device *pdev)
{
struct rtc_device *rtc;
rtc = devm_rtc_device_register(&pdev->dev, "sun4v",
&sun4v_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
platform_set_drvdata(pdev, rtc);
return 0;
}
static struct platform_driver sun4v_rtc_driver = {
.driver = {
.name = "rtc-sun4v",
},
};
builtin_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe);
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