Revision 73863ab028579ed98c4f1f36d016536b1b415344 authored by Anton Vorontsov on 31 May 2012, 23:26:23 UTC, committed by Linus Torvalds on 01 June 2012, 00:49:29 UTC
Current CPU hotplug code has some task->mm handling issues: 1. Working with task->mm w/o getting mm or grabing the task lock is dangerous as ->mm might disappear (exit_mm() assigns NULL under task_lock(), so tasklist lock is not enough). We can't use get_task_mm()/mmput() pair as mmput() might sleep, so we must take the task lock while handle its mm. 2. Checking for process->mm is not enough because process' main thread may exit or detach its mm via use_mm(), but other threads may still have a valid mm. To fix this we would need to use find_lock_task_mm(), which would walk up all threads and returns an appropriate task (with task lock held). clear_tasks_mm_cpumask() has all the issues fixed, so let's use it. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 3eaa73b
rtc-tile.c
/*
* Copyright 2011 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* Tilera-specific RTC driver.
*/
#include <linux/module.h>
#include <linux/device.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
/* Platform device pointer. */
static struct platform_device *tile_rtc_platform_device;
/*
* RTC read routine. Gets time info from RTC chip via hypervisor syscall.
*/
static int read_rtc_time(struct device *dev, struct rtc_time *tm)
{
HV_RTCTime hvtm = hv_get_rtc();
tm->tm_sec = hvtm.tm_sec;
tm->tm_min = hvtm.tm_min;
tm->tm_hour = hvtm.tm_hour;
tm->tm_mday = hvtm.tm_mday;
tm->tm_mon = hvtm.tm_mon;
tm->tm_year = hvtm.tm_year;
tm->tm_wday = 0;
tm->tm_yday = 0;
tm->tm_isdst = 0;
if (rtc_valid_tm(tm) < 0)
dev_warn(dev, "Read invalid date/time from RTC\n");
return 0;
}
/*
* RTC write routine. Sends time info to hypervisor via syscall, to be
* written to RTC chip.
*/
static int set_rtc_time(struct device *dev, struct rtc_time *tm)
{
HV_RTCTime hvtm;
hvtm.tm_sec = tm->tm_sec;
hvtm.tm_min = tm->tm_min;
hvtm.tm_hour = tm->tm_hour;
hvtm.tm_mday = tm->tm_mday;
hvtm.tm_mon = tm->tm_mon;
hvtm.tm_year = tm->tm_year;
hv_set_rtc(hvtm);
return 0;
}
/*
* RTC read/write ops.
*/
static const struct rtc_class_ops tile_rtc_ops = {
.read_time = read_rtc_time,
.set_time = set_rtc_time,
};
/*
* Device probe routine.
*/
static int __devinit tile_rtc_probe(struct platform_device *dev)
{
struct rtc_device *rtc;
rtc = rtc_device_register("tile",
&dev->dev, &tile_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
platform_set_drvdata(dev, rtc);
return 0;
}
/*
* Device cleanup routine.
*/
static int __devexit tile_rtc_remove(struct platform_device *dev)
{
struct rtc_device *rtc = platform_get_drvdata(dev);
if (rtc)
rtc_device_unregister(rtc);
platform_set_drvdata(dev, NULL);
return 0;
}
static struct platform_driver tile_rtc_platform_driver = {
.driver = {
.name = "rtc-tile",
.owner = THIS_MODULE,
},
.probe = tile_rtc_probe,
.remove = __devexit_p(tile_rtc_remove),
};
/*
* Driver init routine.
*/
static int __init tile_rtc_driver_init(void)
{
int err;
err = platform_driver_register(&tile_rtc_platform_driver);
if (err)
return err;
tile_rtc_platform_device = platform_device_alloc("rtc-tile", 0);
if (tile_rtc_platform_device == NULL) {
err = -ENOMEM;
goto exit_driver_unregister;
}
err = platform_device_add(tile_rtc_platform_device);
if (err)
goto exit_device_put;
return 0;
exit_device_put:
platform_device_put(tile_rtc_platform_device);
exit_driver_unregister:
platform_driver_unregister(&tile_rtc_platform_driver);
return err;
}
/*
* Driver cleanup routine.
*/
static void __exit tile_rtc_driver_exit(void)
{
platform_driver_unregister(&tile_rtc_platform_driver);
}
module_init(tile_rtc_driver_init);
module_exit(tile_rtc_driver_exit);
MODULE_DESCRIPTION("Tilera-specific Real Time Clock Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rtc-tile");
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...