/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
 * (C) 2011 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/ip.h>
#include <net/ip.h>

#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_l3proto.h>

static int __net_init iptable_nat_table_init(struct net *net);

static const struct xt_table nf_nat_ipv4_table = {
	.name		= "nat",
	.valid_hooks	= (1 << NF_INET_PRE_ROUTING) |
			  (1 << NF_INET_POST_ROUTING) |
			  (1 << NF_INET_LOCAL_OUT) |
			  (1 << NF_INET_LOCAL_IN),
	.me		= THIS_MODULE,
	.af		= NFPROTO_IPV4,
	.table_init	= iptable_nat_table_init,
};

static unsigned int iptable_nat_do_chain(void *priv,
					 struct sk_buff *skb,
					 const struct nf_hook_state *state,
					 struct nf_conn *ct)
{
	return ipt_do_table(skb, state, state->net->ipv4.nat_table);
}

static unsigned int iptable_nat_ipv4_fn(void *priv,
					struct sk_buff *skb,
					const struct nf_hook_state *state)
{
	return nf_nat_ipv4_fn(priv, skb, state, iptable_nat_do_chain);
}

static unsigned int iptable_nat_ipv4_in(void *priv,
					struct sk_buff *skb,
					const struct nf_hook_state *state)
{
	return nf_nat_ipv4_in(priv, skb, state, iptable_nat_do_chain);
}

static unsigned int iptable_nat_ipv4_out(void *priv,
					 struct sk_buff *skb,
					 const struct nf_hook_state *state)
{
	return nf_nat_ipv4_out(priv, skb, state, iptable_nat_do_chain);
}

static unsigned int iptable_nat_ipv4_local_fn(void *priv,
					      struct sk_buff *skb,
					      const struct nf_hook_state *state)
{
	return nf_nat_ipv4_local_fn(priv, skb, state, iptable_nat_do_chain);
}

static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = {
	/* Before packet filtering, change destination */
	{
		.hook		= iptable_nat_ipv4_in,
		.pf		= NFPROTO_IPV4,
		.hooknum	= NF_INET_PRE_ROUTING,
		.priority	= NF_IP_PRI_NAT_DST,
	},
	/* After packet filtering, change source */
	{
		.hook		= iptable_nat_ipv4_out,
		.pf		= NFPROTO_IPV4,
		.hooknum	= NF_INET_POST_ROUTING,
		.priority	= NF_IP_PRI_NAT_SRC,
	},
	/* Before packet filtering, change destination */
	{
		.hook		= iptable_nat_ipv4_local_fn,
		.pf		= NFPROTO_IPV4,
		.hooknum	= NF_INET_LOCAL_OUT,
		.priority	= NF_IP_PRI_NAT_DST,
	},
	/* After packet filtering, change source */
	{
		.hook		= iptable_nat_ipv4_fn,
		.pf		= NFPROTO_IPV4,
		.hooknum	= NF_INET_LOCAL_IN,
		.priority	= NF_IP_PRI_NAT_SRC,
	},
};

static int __net_init iptable_nat_table_init(struct net *net)
{
	struct ipt_replace *repl;
	int ret;

	if (net->ipv4.nat_table)
		return 0;

	repl = ipt_alloc_initial_table(&nf_nat_ipv4_table);
	if (repl == NULL)
		return -ENOMEM;
	ret = ipt_register_table(net, &nf_nat_ipv4_table, repl,
				 nf_nat_ipv4_ops, &net->ipv4.nat_table);
	kfree(repl);
	return ret;
}

static void __net_exit iptable_nat_net_exit(struct net *net)
{
	if (!net->ipv4.nat_table)
		return;
	ipt_unregister_table(net, net->ipv4.nat_table, nf_nat_ipv4_ops);
	net->ipv4.nat_table = NULL;
}

static struct pernet_operations iptable_nat_net_ops = {
	.exit	= iptable_nat_net_exit,
};

static int __init iptable_nat_init(void)
{
	int ret = register_pernet_subsys(&iptable_nat_net_ops);

	if (ret)
		return ret;

	ret = iptable_nat_table_init(&init_net);
	if (ret)
		unregister_pernet_subsys(&iptable_nat_net_ops);
	return ret;
}

static void __exit iptable_nat_exit(void)
{
	unregister_pernet_subsys(&iptable_nat_net_ops);
}

module_init(iptable_nat_init);
module_exit(iptable_nat_exit);

MODULE_LICENSE("GPL");
<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>Davidlohr Bueso &lt;dave@stgolabs.net&gt;</td><td class='right'>2016-04-17 23:31:41 -0700</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2016-04-19 10:49:19 +0200</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/Documentation/thermal?id=6687659568e2ec5b3ac24b39c5d26ce8b9d90434'>6687659568e2ec5b3ac24b39c5d26ce8b9d90434</a> (<a href='/cgit.cgi/linux/net-next.git/patch/Documentation/thermal?id=6687659568e2ec5b3ac24b39c5d26ce8b9d90434'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=6687659568e2ec5b3ac24b39c5d26ce8b9d90434'>e8a09031737ca3499941a9df9205a6578d5706df</a> /<a href='/cgit.cgi/linux/net-next.git/tree/Documentation/thermal?id=6687659568e2ec5b3ac24b39c5d26ce8b9d90434'>Documentation/thermal</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/Documentation/thermal?id=c3b46c73264b03000d1e18b22f5caf63332547c9'>c3b46c73264b03000d1e18b22f5caf63332547c9</a> (<a href='/cgit.cgi/linux/net-next.git/diff/Documentation/thermal?id=6687659568e2ec5b3ac24b39c5d26ce8b9d90434&amp;id2=c3b46c73264b03000d1e18b22f5caf63332547c9'>diff</a>)</td></tr></table>
<div class='commit-subject'>locking/pvqspinlock: Fix division by zero in qstat_read()</div><div class='commit-msg'>While playing with the qstat statistics (in &lt;debugfs&gt;/qlockstat/) I ran into
the following splat on a VM when opening pv_hash_hops:

  divide error: 0000 [#1] SMP
  ...
  RIP: 0010:[&lt;ffffffff810b61fe&gt;]  [&lt;ffffffff810b61fe&gt;] qstat_read+0x12e/0x1e0
  ...
  Call Trace:
    [&lt;ffffffff811cad7c&gt;] ? mem_cgroup_commit_charge+0x6c/0xd0
    [&lt;ffffffff8119750c&gt;] ? page_add_new_anon_rmap+0x8c/0xd0
    [&lt;ffffffff8118d3b9&gt;] ? handle_mm_fault+0x1439/0x1b40
    [&lt;ffffffff811937a9&gt;] ? do_mmap+0x449/0x550
    [&lt;ffffffff811d3de3&gt;] ? __vfs_read+0x23/0xd0
    [&lt;ffffffff811d4ab2&gt;] ? rw_verify_area+0x52/0xd0
    [&lt;ffffffff811d4bb1&gt;] ? vfs_read+0x81/0x120
    [&lt;ffffffff811d5f12&gt;] ? SyS_read+0x42/0xa0
    [&lt;ffffffff815720f6&gt;] ? entry_SYSCALL_64_fastpath+0x1e/0xa8

Fix this by verifying that qstat_pv_kick_unlock is in fact non-zero,
similarly to what the qstat_pv_latency_wake case does, as if nothing
else, this can come from resetting the statistics, thus having 0 kicks
should be quite valid in this context.

Signed-off-by: Davidlohr Bueso &lt;dbueso@suse.de&gt;
Reviewed-by: Waiman Long &lt;Waiman.Long@hpe.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: dave@stgolabs.net
Cc: waiman.long@hpe.com
Link: http://lkml.kernel.org/r/1460961103-24953-1-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=6687659568e2ec5b3ac24b39c5d26ce8b9d90434'>Diffstat</a> (limited to 'Documentation/thermal')</div><table summary='diffstat' class='diffstat'>