/*
 *  net/dccp/diag.c
 *
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@mandriva.com>
 *
 *	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/inet_diag.h>

#include "ccid.h"
#include "dccp.h"

static void dccp_get_info(struct sock *sk, struct tcp_info *info)
{
	struct dccp_sock *dp = dccp_sk(sk);
	const struct inet_connection_sock *icsk = inet_csk(sk);

	memset(info, 0, sizeof(*info));

	info->tcpi_state	= sk->sk_state;
	info->tcpi_retransmits	= icsk->icsk_retransmits;
	info->tcpi_probes	= icsk->icsk_probes_out;
	info->tcpi_backoff	= icsk->icsk_backoff;
	info->tcpi_pmtu		= icsk->icsk_pmtu_cookie;

	if (dp->dccps_hc_rx_ackvec != NULL)
		info->tcpi_options |= TCPI_OPT_SACK;

	if (dp->dccps_hc_rx_ccid != NULL)
		ccid_hc_rx_get_info(dp->dccps_hc_rx_ccid, sk, info);

	if (dp->dccps_hc_tx_ccid != NULL)
		ccid_hc_tx_get_info(dp->dccps_hc_tx_ccid, sk, info);
}

static void dccp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
			       void *_info)
{
	r->idiag_rqueue = r->idiag_wqueue = 0;

	if (_info != NULL)
		dccp_get_info(sk, _info);
}

static void dccp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
			   const struct inet_diag_req_v2 *r, struct nlattr *bc)
{
	inet_diag_dump_icsk(&dccp_hashinfo, skb, cb, r, bc);
}

static int dccp_diag_dump_one(struct sk_buff *in_skb,
			      const struct nlmsghdr *nlh,
			      const struct inet_diag_req_v2 *req)
{
	return inet_diag_dump_one_icsk(&dccp_hashinfo, in_skb, nlh, req);
}

static const struct inet_diag_handler dccp_diag_handler = {
	.dump		 = dccp_diag_dump,
	.dump_one	 = dccp_diag_dump_one,
	.idiag_get_info	 = dccp_diag_get_info,
	.idiag_type	 = IPPROTO_DCCP,
	.idiag_info_size = sizeof(struct tcp_info),
};

static int __init dccp_diag_init(void)
{
	return inet_diag_register(&dccp_diag_handler);
}

static void __exit dccp_diag_fini(void)
{
	inet_diag_unregister(&dccp_diag_handler);
}

module_init(dccp_diag_init);
module_exit(dccp_diag_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
MODULE_DESCRIPTION("DCCP inet_diag handler");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-33 /* AF_INET - IPPROTO_DCCP */);
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/drivers?id=966d2b04e070bc040319aaebfec09e0144dc3341'>drivers</a>/<a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb?id=966d2b04e070bc040319aaebfec09e0144dc3341'>usb</a>/<a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb/host?id=966d2b04e070bc040319aaebfec09e0144dc3341'>host</a>/<a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb/host/ohci-spear.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>ohci-spear.c</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><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/drivers/usb/host/ohci-spear.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/drivers/usb/host/ohci-spear.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/drivers/usb/host/ohci-spear.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>drivers/usb/host/ohci-spear.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb/host/ohci-spear.c?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/drivers/usb/host/ohci-spear.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 'drivers/usb/host/ohci-spear.c')</div><table summary='diffstat' class='diffstat'>