/*
 *	STP SAP demux
 *
 *	Copyright (c) 2008 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/mutex.h>
#include <linux/skbuff.h>
#include <linux/etherdevice.h>
#include <linux/llc.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <net/llc.h>
#include <net/llc_pdu.h>
#include <net/stp.h>

/* 01:80:c2:00:00:20 - 01:80:c2:00:00:2F */
#define GARP_ADDR_MIN	0x20
#define GARP_ADDR_MAX	0x2F
#define GARP_ADDR_RANGE	(GARP_ADDR_MAX - GARP_ADDR_MIN)

static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
static const struct stp_proto __rcu *stp_proto __read_mostly;

static struct llc_sap *sap __read_mostly;
static unsigned int sap_registered;
static DEFINE_MUTEX(stp_proto_mutex);

/* Called under rcu_read_lock from LLC */
static int stp_pdu_rcv(struct sk_buff *skb, struct net_device *dev,
		       struct packet_type *pt, struct net_device *orig_dev)
{
	const struct ethhdr *eh = eth_hdr(skb);
	const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
	const struct stp_proto *proto;

	if (pdu->ssap != LLC_SAP_BSPAN ||
	    pdu->dsap != LLC_SAP_BSPAN ||
	    pdu->ctrl_1 != LLC_PDU_TYPE_U)
		goto err;

	if (eh->h_dest[5] >= GARP_ADDR_MIN && eh->h_dest[5] <= GARP_ADDR_MAX) {
		proto = rcu_dereference(garp_protos[eh->h_dest[5] -
						    GARP_ADDR_MIN]);
		if (proto &&
		    !ether_addr_equal(eh->h_dest, proto->group_address))
			goto err;
	} else
		proto = rcu_dereference(stp_proto);

	if (!proto)
		goto err;

	proto->rcv(proto, skb, dev);
	return 0;

err:
	kfree_skb(skb);
	return 0;
}

int stp_proto_register(const struct stp_proto *proto)
{
	int err = 0;

	mutex_lock(&stp_proto_mutex);
	if (sap_registered++ == 0) {
		sap = llc_sap_open(LLC_SAP_BSPAN, stp_pdu_rcv);
		if (!sap) {
			err = -ENOMEM;
			goto out;
		}
	}
	if (is_zero_ether_addr(proto->group_address))
		rcu_assign_pointer(stp_proto, proto);
	else
		rcu_assign_pointer(garp_protos[proto->group_address[5] -
					       GARP_ADDR_MIN], proto);
out:
	mutex_unlock(&stp_proto_mutex);
	return err;
}
EXPORT_SYMBOL_GPL(stp_proto_register);

void stp_proto_unregister(const struct stp_proto *proto)
{
	mutex_lock(&stp_proto_mutex);
	if (is_zero_ether_addr(proto->group_address))
		RCU_INIT_POINTER(stp_proto, NULL);
	else
		RCU_INIT_POINTER(garp_protos[proto->group_address[5] -
					       GARP_ADDR_MIN], NULL);
	synchronize_rcu();

	if (--sap_registered == 0)
		llc_sap_put(sap);
	mutex_unlock(&stp_proto_mutex);
}
EXPORT_SYMBOL_GPL(stp_proto_unregister);

MODULE_LICENSE("GPL");
>path: <a href='/cgit.cgi/linux/net-next.git/commit/?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/Documentation?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>Documentation</a>/<a href='/cgit.cgi/linux/net-next.git/commit/Documentation/sysrq.txt?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>sysrq.txt</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='25ccd2429fd0af5b9c2c136c8c593491aeabf162'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='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>Lv Zheng &lt;zetalog@gmail.com&gt;</td><td class='right'>2016-10-26 15:40:12 +0800</td></tr>
<tr><th>committer</th><td>Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;</td><td class='right'>2016-10-29 01:57:43 +0200</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/Documentation/sysrq.txt?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>25ccd2429fd0af5b9c2c136c8c593491aeabf162</a> (<a href='/cgit.cgi/linux/net-next.git/patch/Documentation/sysrq.txt?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>6e42efd5429fddba4bdaf301708c7e2b9870e8f6</a> /<a href='/cgit.cgi/linux/net-next.git/tree/Documentation/sysrq.txt?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>Documentation/sysrq.txt</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/Documentation/sysrq.txt?id=07d9a380680d1c0eb51ef87ff2eab5c994949e69'>07d9a380680d1c0eb51ef87ff2eab5c994949e69</a> (<a href='/cgit.cgi/linux/net-next.git/diff/Documentation/sysrq.txt?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162&amp;id2=07d9a380680d1c0eb51ef87ff2eab5c994949e69'>diff</a>)</td></tr></table>
<div class='commit-subject'>ACPICA: Dispatcher: Fix order issue of method termination</div><div class='commit-msg'>The last step of the method termination should be the end of the method
serialization. Otherwise, the steps happening after it will face the race
issues that cannot be protected by the method serialization mechanism.

This patch fixes this issue by moving the per-method-object deletion code
prior than the end of the method serialization. Otherwise, the possible
race issues may result in AE_ALREADY_EXISTS error in a parallel
environment.

Fixes: 74f51b80a0c4 (ACPICA: Namespace: Fix dynamic table loading issues)
Reported-and-tested-by: Imre Deak &lt;imre.deak@intel.com&gt;
Signed-off-by: Lv Zheng &lt;lv.zheng@intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=25ccd2429fd0af5b9c2c136c8c593491aeabf162'>Diffstat</a> (limited to 'Documentation/sysrq.txt')</div><table summary='diffstat' class='diffstat'>