Skip to main content

Browse the archive

Revision 475049809977bf3975d78f2d2fd992e19ce2d59e authored by Roel Kluin on 10 March 2009, 19:55:45 UTC, committed by Linus Torvalds on 10 March 2009, 22:55:10 UTC 
mm: get_nid_for_pfn() returns int
 
get_nid_for_pfn() returns int

Presumably the (nid < 0) case has never happened.

We do know that it is happening on one system while creating a symlink for
a memory section so it should also happen on the same system if
unregister_mem_sect_under_nodes() were called to remove the same symlink.

The test was actually added in response to a problem with an earlier
version reported by Yasunori Goto where one or more of the leading pages
of a memory section on the 2nd node of one of his systems was
uninitialized because I believe they coincided with a memory hole.

That earlier version did not ignore uninitialized pages and determined
the nid by considering only the 1st page of each memory section.  This
caused the symlink to the 1st memory section on the 2nd node to be
incorrectly created in /sys/devices/system/node/node0 instead of
/sys/devices/system/node/node1.  The problem was fixed by adding the
test to skip over uninitialized pages.

I suspect we have not seen any reports of the non-removal
of a symlink due to the incorrect declaration of the nid
variable in unregister_mem_sect_under_nodes() because
  - systems where a memory section could have an uninitialized
    range of leading pages are probably rare.
  - memory remove is probably not done very frequently on the
    systems that are capable of demonstrating the problem.
  - lingering symlink(s) that should have been removed may
    have simply gone unnoticed.

[garyhade@us.ibm.com: wrote changelog]
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 1abaf33
Raw File
umc-dev.c 
/*
 * UWB Multi-interface Controller device management.
 *
 * Copyright (C) 2007 Cambridge Silicon Radio Ltd.
 *
 * This file is released under the GNU GPL v2.
 */
#include <linux/kernel.h>
#include <linux/uwb/umc.h>

static void umc_device_release(struct device *dev)
{
	struct umc_dev *umc = to_umc_dev(dev);

	kfree(umc);
}

/**
 * umc_device_create - allocate a child UMC device
 * @parent: parent of the new UMC device.
 * @n:      index of the new device.
 *
 * The new UMC device will have a bus ID of the parent with '-n'
 * appended.
 */
struct umc_dev *umc_device_create(struct device *parent, int n)
{
	struct umc_dev *umc;

	umc = kzalloc(sizeof(struct umc_dev), GFP_KERNEL);
	if (umc) {
		dev_set_name(&umc->dev, "%s-%d", dev_name(parent), n);
		umc->dev.parent  = parent;
		umc->dev.bus     = &umc_bus_type;
		umc->dev.release = umc_device_release;

		umc->dev.dma_mask = parent->dma_mask;
	}
	return umc;
}
EXPORT_SYMBOL_GPL(umc_device_create);

/**
 * umc_device_register - register a UMC device
 * @umc: pointer to the UMC device
 *
 * The memory resource for the UMC device is acquired and the device
 * registered with the system.
 */
int umc_device_register(struct umc_dev *umc)
{
	int err;

	err = request_resource(umc->resource.parent, &umc->resource);
	if (err < 0) {
		dev_err(&umc->dev, "can't allocate resource range "
			"%016Lx to %016Lx: %d\n",
			(unsigned long long)umc->resource.start,
			(unsigned long long)umc->resource.end,
			err);
		goto error_request_resource;
	}

	err = device_register(&umc->dev);
	if (err < 0)
		goto error_device_register;
	return 0;

error_device_register:
	release_resource(&umc->resource);
error_request_resource:
	return err;
}
EXPORT_SYMBOL_GPL(umc_device_register);

/**
 * umc_device_unregister - unregister a UMC device
 * @umc: pointer to the UMC device
 *
 * First we unregister the device, make sure the driver can do it's
 * resource release thing and then we try to release any left over
 * resources. We take a ref to the device, to make sure it doesn't
 * dissapear under our feet.
 */
void umc_device_unregister(struct umc_dev *umc)
{
	struct device *dev;
	if (!umc)
		return;
	dev = get_device(&umc->dev);
	device_unregister(&umc->dev);
	release_resource(&umc->resource);
	put_device(dev);
}
EXPORT_SYMBOL_GPL(umc_device_unregister);
back to top