/*
 * Copyright (c) 2016, Amir Vadai <amir@vadai.me>
 * Copyright (c) 2016, Mellanox Technologies. All rights reserved.
 *
 * 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.
 */

#ifndef __NET_TC_TUNNEL_KEY_H
#define __NET_TC_TUNNEL_KEY_H

#include <net/act_api.h>
#include <linux/tc_act/tc_tunnel_key.h>
#include <net/dst_metadata.h>

struct tcf_tunnel_key_params {
	struct rcu_head		rcu;
	int			tcft_action;
	int			action;
	struct metadata_dst     *tcft_enc_metadata;
};

struct tcf_tunnel_key {
	struct tc_action	      common;
	struct tcf_tunnel_key_params __rcu *params;
};

#define to_tunnel_key(a) ((struct tcf_tunnel_key *)a)

static inline bool is_tcf_tunnel_set(const struct tc_action *a)
{
#ifdef CONFIG_NET_CLS_ACT
	struct tcf_tunnel_key *t = to_tunnel_key(a);
	struct tcf_tunnel_key_params *params = rtnl_dereference(t->params);

	if (a->ops && a->ops->type == TCA_ACT_TUNNEL_KEY)
		return params->tcft_action == TCA_TUNNEL_KEY_ACT_SET;
#endif
	return false;
}

static inline bool is_tcf_tunnel_release(const struct tc_action *a)
{
#ifdef CONFIG_NET_CLS_ACT
	struct tcf_tunnel_key *t = to_tunnel_key(a);
	struct tcf_tunnel_key_params *params = rtnl_dereference(t->params);

	if (a->ops && a->ops->type == TCA_ACT_TUNNEL_KEY)
		return params->tcft_action == TCA_TUNNEL_KEY_ACT_RELEASE;
#endif
	return false;
}

static inline struct ip_tunnel_info *tcf_tunnel_info(const struct tc_action *a)
{
#ifdef CONFIG_NET_CLS_ACT
	struct tcf_tunnel_key *t = to_tunnel_key(a);
	struct tcf_tunnel_key_params *params = rtnl_dereference(t->params);

	return &params->tcft_enc_metadata->u.tun_info;
#else
	return NULL;
#endif
}
#endif /* __NET_TC_TUNNEL_KEY_H */
t.git/commit/net/ipv6/xfrm6_state.c?id=f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3'>commit</a><a href='/cgit.cgi/linux/net-next.git/diff/net/ipv6/xfrm6_state.c?id=f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3'>diff</a></td><td class='form'><form class='right' method='get' action='/cgit.cgi/linux/net-next.git/log/net/ipv6/xfrm6_state.c'>
<input type='hidden' name='id' value='f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?id=f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/net?id=f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3'>net</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/ipv6?id=f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3'>ipv6</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/ipv6/xfrm6_state.c?id=f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3'>xfrm6_state.c</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/net/ipv6/xfrm6_state.c?id=f32f5bd2eb7e91a5090c06bbe1ed14bffbbda5d3&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
ption 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/dcb/dcbnl.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/dcb/dcbnl.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/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/dcb/dcbnl.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/dcb/dcbnl.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/dcb/dcbnl.c?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/dcb/dcbnl.c?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/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'net/dcb/dcbnl.c')</div><table summary='diffstat' class='diffstat'>