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
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
dm-path-selector.c
/*
* Copyright (C) 2003 Sistina Software.
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
*
* Module Author: Heinz Mauelshagen
*
* This file is released under the GPL.
*
* Path selector registration.
*/
#include <linux/device-mapper.h>
#include "dm-path-selector.h"
#include <linux/slab.h>
struct ps_internal {
struct path_selector_type pst;
struct list_head list;
long use;
};
#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)
static LIST_HEAD(_path_selectors);
static DECLARE_RWSEM(_ps_lock);
static struct ps_internal *__find_path_selector_type(const char *name)
{
struct ps_internal *psi;
list_for_each_entry(psi, &_path_selectors, list) {
if (!strcmp(name, psi->pst.name))
return psi;
}
return NULL;
}
static struct ps_internal *get_path_selector(const char *name)
{
struct ps_internal *psi;
down_read(&_ps_lock);
psi = __find_path_selector_type(name);
if (psi) {
if ((psi->use == 0) && !try_module_get(psi->pst.module))
psi = NULL;
else
psi->use++;
}
up_read(&_ps_lock);
return psi;
}
struct path_selector_type *dm_get_path_selector(const char *name)
{
struct ps_internal *psi;
if (!name)
return NULL;
psi = get_path_selector(name);
if (!psi) {
request_module("dm-%s", name);
psi = get_path_selector(name);
}
return psi ? &psi->pst : NULL;
}
void dm_put_path_selector(struct path_selector_type *pst)
{
struct ps_internal *psi;
if (!pst)
return;
down_read(&_ps_lock);
psi = __find_path_selector_type(pst->name);
if (!psi)
goto out;
if (--psi->use == 0)
module_put(psi->pst.module);
BUG_ON(psi->use < 0);
out:
up_read(&_ps_lock);
}
static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst)
{
struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL);
if (psi)
psi->pst = *pst;
return psi;
}
int dm_register_path_selector(struct path_selector_type *pst)
{
int r = 0;
struct ps_internal *psi = _alloc_path_selector(pst);
if (!psi)
return -ENOMEM;
down_write(&_ps_lock);
if (__find_path_selector_type(pst->name)) {
kfree(psi);
r = -EEXIST;
} else
list_add(&psi->list, &_path_selectors);
up_write(&_ps_lock);
return r;
}
int dm_unregister_path_selector(struct path_selector_type *pst)
{
struct ps_internal *psi;
down_write(&_ps_lock);
psi = __find_path_selector_type(pst->name);
if (!psi) {
up_write(&_ps_lock);
return -EINVAL;
}
if (psi->use) {
up_write(&_ps_lock);
return -ETXTBSY;
}
list_del(&psi->list);
up_write(&_ps_lock);
kfree(psi);
return 0;
}
EXPORT_SYMBOL_GPL(dm_register_path_selector);
EXPORT_SYMBOL_GPL(dm_unregister_path_selector);
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