Revision 4dc2287c1805e7fe8a7cb90bbcd44abee8cdb914 authored by Bjorn Helgaas on 16 December 2010, 17:38:56 UTC, committed by Jesse Barnes on 17 December 2010, 18:01:24 UTC
When we allocate address space, e.g., to assign it to a PCI device, don't allocate anything mentioned in the BIOS E820 memory map. On recent machines (2008 and newer), we assign PCI resources from the windows described by the ACPI PCI host bridge _CRS. On many Dell machines, these windows overlap some E820 reserved areas, e.g., BIOS-e820: 00000000bfe4dc00 - 00000000c0000000 (reserved) pci_root PNP0A03:00: host bridge window [mem 0xbff00000-0xdfffffff] If we put devices at 0xbff00000, they don't work, probably because that's really RAM, not I/O memory. This patch prevents that by removing the 0xbfe4dc00-0xbfffffff area from the "available" resource. I'm not very happy with this solution because Windows solves the problem differently (it seems to ignore E820 reserved areas and it allocates top-down instead of bottom-up; details at comment 45 of the bugzilla below). That means we're vulnerable to BIOS defects that Windows would not trip over. For example, if BIOS described a device in ACPI but didn't mention it in E820, Windows would work fine but Linux would fail. Reference: https://bugzilla.kernel.org/show_bug.cgi?id=16228 Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
1 parent 30919b0
namespace.c
/*
* linux/ipc/namespace.c
* Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
*/
#include <linux/ipc.h>
#include <linux/msg.h>
#include <linux/ipc_namespace.h>
#include <linux/rcupdate.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include "util.h"
static struct ipc_namespace *create_ipc_ns(void)
{
struct ipc_namespace *ns;
int err;
ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
if (ns == NULL)
return ERR_PTR(-ENOMEM);
atomic_set(&ns->count, 1);
err = mq_init_ns(ns);
if (err) {
kfree(ns);
return ERR_PTR(err);
}
atomic_inc(&nr_ipc_ns);
sem_init_ns(ns);
msg_init_ns(ns);
shm_init_ns(ns);
/*
* msgmni has already been computed for the new ipc ns.
* Thus, do the ipcns creation notification before registering that
* new ipcns in the chain.
*/
ipcns_notify(IPCNS_CREATED);
register_ipcns_notifier(ns);
return ns;
}
struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
{
if (!(flags & CLONE_NEWIPC))
return get_ipc_ns(ns);
return create_ipc_ns();
}
/*
* free_ipcs - free all ipcs of one type
* @ns: the namespace to remove the ipcs from
* @ids: the table of ipcs to free
* @free: the function called to free each individual ipc
*
* Called for each kind of ipc when an ipc_namespace exits.
*/
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
{
struct kern_ipc_perm *perm;
int next_id;
int total, in_use;
down_write(&ids->rw_mutex);
in_use = ids->in_use;
for (total = 0, next_id = 0; total < in_use; next_id++) {
perm = idr_find(&ids->ipcs_idr, next_id);
if (perm == NULL)
continue;
ipc_lock_by_ptr(perm);
free(ns, perm);
total++;
}
up_write(&ids->rw_mutex);
}
static void free_ipc_ns(struct ipc_namespace *ns)
{
/*
* Unregistering the hotplug notifier at the beginning guarantees
* that the ipc namespace won't be freed while we are inside the
* callback routine. Since the blocking_notifier_chain_XXX routines
* hold a rw lock on the notifier list, unregister_ipcns_notifier()
* won't take the rw lock before blocking_notifier_call_chain() has
* released the rd lock.
*/
unregister_ipcns_notifier(ns);
sem_exit_ns(ns);
msg_exit_ns(ns);
shm_exit_ns(ns);
kfree(ns);
atomic_dec(&nr_ipc_ns);
/*
* Do the ipcns removal notification after decrementing nr_ipc_ns in
* order to have a correct value when recomputing msgmni.
*/
ipcns_notify(IPCNS_REMOVED);
}
/*
* put_ipc_ns - drop a reference to an ipc namespace.
* @ns: the namespace to put
*
* If this is the last task in the namespace exiting, and
* it is dropping the refcount to 0, then it can race with
* a task in another ipc namespace but in a mounts namespace
* which has this ipcns's mqueuefs mounted, doing some action
* with one of the mqueuefs files. That can raise the refcount.
* So dropping the refcount, and raising the refcount when
* accessing it through the VFS, are protected with mq_lock.
*
* (Clearly, a task raising the refcount on its own ipc_ns
* needn't take mq_lock since it can't race with the last task
* in the ipcns exiting).
*/
void put_ipc_ns(struct ipc_namespace *ns)
{
if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
mq_clear_sbinfo(ns);
spin_unlock(&mq_lock);
mq_put_mnt(ns);
free_ipc_ns(ns);
}
}
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...