/*
 *  UDPLITEv6   An implementation of the UDP-Lite protocol over IPv6.
 *              See also net/ipv4/udplite.c
 *
 *  Authors:    Gerrit Renker       <gerrit@erg.abdn.ac.uk>
 *
 *  Changes:
 *  Fixes:
 *		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/export.h>
#include "udp_impl.h"

static int udplitev6_rcv(struct sk_buff *skb)
{
	return __udp6_lib_rcv(skb, &udplite_table, IPPROTO_UDPLITE);
}

static void udplitev6_err(struct sk_buff *skb,
			  struct inet6_skb_parm *opt,
			  u8 type, u8 code, int offset, __be32 info)
{
	__udp6_lib_err(skb, opt, type, code, offset, info, &udplite_table);
}

static const struct inet6_protocol udplitev6_protocol = {
	.handler	=	udplitev6_rcv,
	.err_handler	=	udplitev6_err,
	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
};

struct proto udplitev6_prot = {
	.name		   = "UDPLITEv6",
	.owner		   = THIS_MODULE,
	.close		   = udp_lib_close,
	.connect	   = ip6_datagram_connect,
	.disconnect	   = udp_disconnect,
	.ioctl		   = udp_ioctl,
	.init		   = udplite_sk_init,
	.destroy	   = udpv6_destroy_sock,
	.setsockopt	   = udpv6_setsockopt,
	.getsockopt	   = udpv6_getsockopt,
	.sendmsg	   = udpv6_sendmsg,
	.recvmsg	   = udpv6_recvmsg,
	.hash		   = udp_lib_hash,
	.unhash		   = udp_lib_unhash,
	.get_port	   = udp_v6_get_port,
	.memory_allocated  = &udp_memory_allocated,
	.sysctl_mem	   = sysctl_udp_mem,
	.obj_size	   = sizeof(struct udp6_sock),
	.h.udp_table	   = &udplite_table,
#ifdef CONFIG_COMPAT
	.compat_setsockopt = compat_udpv6_setsockopt,
	.compat_getsockopt = compat_udpv6_getsockopt,
#endif
};

static struct inet_protosw udplite6_protosw = {
	.type		= SOCK_DGRAM,
	.protocol	= IPPROTO_UDPLITE,
	.prot		= &udplitev6_prot,
	.ops		= &inet6_dgram_ops,
	.flags		= INET_PROTOSW_PERMANENT,
};

int __init udplitev6_init(void)
{
	int ret;

	ret = inet6_add_protocol(&udplitev6_protocol, IPPROTO_UDPLITE);
	if (ret)
		goto out;

	ret = inet6_register_protosw(&udplite6_protosw);
	if (ret)
		goto out_udplitev6_protocol;
out:
	return ret;

out_udplitev6_protocol:
	inet6_del_protocol(&udplitev6_protocol, IPPROTO_UDPLITE);
	goto out;
}

void udplitev6_exit(void)
{
	inet6_unregister_protosw(&udplite6_protosw);
	inet6_del_protocol(&udplitev6_protocol, IPPROTO_UDPLITE);
}

#ifdef CONFIG_PROC_FS

static const struct file_operations udplite6_afinfo_seq_fops = {
	.owner    = THIS_MODULE,
	.open     = udp_seq_open,
	.read     = seq_read,
	.llseek   = seq_lseek,
	.release  = seq_release_net
};

static struct udp_seq_afinfo udplite6_seq_afinfo = {
	.name		= "udplite6",
	.family		= AF_INET6,
	.udp_table	= &udplite_table,
	.seq_fops	= &udplite6_afinfo_seq_fops,
	.seq_ops	= {
		.show		= udp6_seq_show,
	},
};

static int __net_init udplite6_proc_init_net(struct net *net)
{
	return udp_proc_register(net, &udplite6_seq_afinfo);
}

static void __net_exit udplite6_proc_exit_net(struct net *net)
{
	udp_proc_unregister(net, &udplite6_seq_afinfo);
}

static struct pernet_operations udplite6_net_ops = {
	.init = udplite6_proc_init_net,
	.exit = udplite6_proc_exit_net,
};

int __init udplite6_proc_init(void)
{
	return register_pernet_subsys(&udplite6_net_ops);
}

void udplite6_proc_exit(void)
{
	unregister_pernet_subsys(&udplite6_net_ops);
}
#endif
bfec09e0144dc3341'>gre_demux.c</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='966d2b04e070bc040319aaebfec09e0144dc3341'/><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>Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;</td><td class='right'>2017-01-28 06:42:20 -0600</td></tr>
<tr><th>committer</th><td>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/ipv4/gre_demux.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/ipv4/gre_demux.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/ipv4/gre_demux.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/ipv4/gre_demux.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/ipv4/gre_demux.c?h=nds-private-remove&amp;id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/ipv4/gre_demux.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'net/ipv4/gre_demux.c')</div><table summary='diffstat' class='diffstat'>