/* getroot.c: get the root dentry for an NFS mount
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/lockd/bind.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/namei.h>
#include <linux/security.h>

#include <linux/uaccess.h>

#include "internal.h"

#define NFSDBG_FACILITY		NFSDBG_CLIENT

/*
 * Set the superblock root dentry.
 * Note that this function frees the inode in case of error.
 */
static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)
{
	/* The mntroot acts as the dummy root dentry for this superblock */
	if (sb->s_root == NULL) {
		sb->s_root = d_make_root(inode);
		if (sb->s_root == NULL)
			return -ENOMEM;
		ihold(inode);
		/*
		 * Ensure that this dentry is invisible to d_find_alias().
		 * Otherwise, it may be spliced into the tree by
		 * d_splice_alias if a parent directory from the same
		 * filesystem gets mounted at a later time.
		 * This again causes shrink_dcache_for_umount_subtree() to
		 * Oops, since the test for IS_ROOT() will fail.
		 */
		spin_lock(&d_inode(sb->s_root)->i_lock);
		spin_lock(&sb->s_root->d_lock);
		hlist_del_init(&sb->s_root->d_u.d_alias);
		spin_unlock(&sb->s_root->d_lock);
		spin_unlock(&d_inode(sb->s_root)->i_lock);
	}
	return 0;
}

/*
 * get an NFS2/NFS3 root dentry from the root filehandle
 */
struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh,
			    const char *devname)
{
	struct nfs_server *server = NFS_SB(sb);
	struct nfs_fsinfo fsinfo;
	struct dentry *ret;
	struct inode *inode;
	void *name = kstrdup(devname, GFP_KERNEL);
	int error;

	if (!name)
		return ERR_PTR(-ENOMEM);

	/* get the actual root for this mount */
	fsinfo.fattr = nfs_alloc_fattr();
	if (fsinfo.fattr == NULL) {
		kfree(name);
		return ERR_PTR(-ENOMEM);
	}

	error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
	if (error < 0) {
		dprintk("nfs_get_root: getattr error = %d\n", -error);
		ret = ERR_PTR(error);
		goto out;
	}

	inode = nfs_fhget(sb, mntfh, fsinfo.fattr, NULL);
	if (IS_ERR(inode)) {
		dprintk("nfs_get_root: get root inode failed\n");
		ret = ERR_CAST(inode);
		goto out;
	}

	error = nfs_superblock_set_dummy_root(sb, inode);
	if (error != 0) {
		ret = ERR_PTR(error);
		goto out;
	}

	/* root dentries normally start off anonymous and get spliced in later
	 * if the dentry tree reaches them; however if the dentry already
	 * exists, we'll pick it up at this point and use it as the root
	 */
	ret = d_obtain_root(inode);
	if (IS_ERR(ret)) {
		dprintk("nfs_get_root: get root dentry failed\n");
		goto out;
	}

	security_d_instantiate(ret, inode);
	spin_lock(&ret->d_lock);
	if (IS_ROOT(ret) && !ret->d_fsdata &&
	    !(ret->d_flags & DCACHE_NFSFS_RENAMED)) {
		ret->d_fsdata = name;
		name = NULL;
	}
	spin_unlock(&ret->d_lock);
out:
	kfree(name);
	nfs_free_fattr(fsinfo.fattr);
	return ret;
}
'4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Bjorn Helgaas &lt;bhelgaas@google.com&gt;</td><td class='right'>2017-01-27 15:00:45 -0600</td></tr>
<tr><th>committer</th><td>Bjorn Helgaas &lt;bhelgaas@google.com&gt;</td><td class='right'>2017-01-27 15:00:45 -0600</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/sctp/associola.c?id=030305d69fc6963c16003f50d7e8d74b02d0a143'>030305d69fc6963c16003f50d7e8d74b02d0a143</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/sctp/associola.c?id=030305d69fc6963c16003f50d7e8d74b02d0a143'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=030305d69fc6963c16003f50d7e8d74b02d0a143'>363a4e34d199178769b7e7eeb26ea2620a55847b</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/sctp/associola.c?id=030305d69fc6963c16003f50d7e8d74b02d0a143'>net/sctp/associola.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/sctp/associola.c?id=4d191b1b63c209e37bf27938ef365244d3c41084'>4d191b1b63c209e37bf27938ef365244d3c41084</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/sctp/associola.c?id=030305d69fc6963c16003f50d7e8d74b02d0a143&amp;id2=4d191b1b63c209e37bf27938ef365244d3c41084'>diff</a>)</td></tr></table>
<div class='commit-subject'>PCI/ASPM: Handle PCI-to-PCIe bridges as roots of PCIe hierarchies</div><div class='commit-msg'>In a struct pcie_link_state, link-&gt;root points to the pcie_link_state of
the root of the PCIe hierarchy.  For the topmost link, this points to
itself (link-&gt;root = link).  For others, we copy the pointer from the
parent (link-&gt;root = link-&gt;parent-&gt;root).

Previously we recognized that Root Ports originated PCIe hierarchies, but
we treated PCI/PCI-X to PCIe Bridges as being in the middle of the
hierarchy, and when we tried to copy the pointer from link-&gt;parent-&gt;root,
there was no parent, and we dereferenced a NULL pointer:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000090
  IP: [&lt;ffffffff9e424350&gt;] pcie_aspm_init_link_state+0x170/0x820

Recognize that PCI/PCI-X to PCIe Bridges originate PCIe hierarchies just
like Root Ports do, so link-&gt;root for these devices should also point to
itself.

Fixes: 51ebfc92b72b ("PCI: Enumerate switches below PCI-to-PCIe bridges")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=193411
Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1022181
Tested-by: lists@ssl-mail.com
Tested-by: Jayachandran C. &lt;jnair@caviumnetworks.com&gt;
Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
CC: stable@vger.kernel.org	# v4.2+</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=030305d69fc6963c16003f50d7e8d74b02d0a143'>Diffstat</a> (limited to 'net/sctp/associola.c')</div><table summary='diffstat' class='diffstat'>