/*
 * llc_s_ev.c - Defines SAP component events
 *
 * The followed event functions are SAP component events which are described
 * in 802.2 LLC protocol standard document.
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 *		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 * This program can be redistributed or modified under the terms of the
 * GNU General Public License as published by the Free Software Foundation.
 * This program is distributed without any warranty or implied warranty
 * of merchantability or fitness for a particular purpose.
 *
 * See the GNU General Public License for more details.
 */
#include <linux/socket.h>
#include <net/sock.h>
#include <net/llc_if.h>
#include <net/llc_s_ev.h>
#include <net/llc_pdu.h>

int llc_sap_ev_activation_req(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);

	return ev->type == LLC_SAP_EV_TYPE_SIMPLE &&
	       ev->prim_type == LLC_SAP_EV_ACTIVATION_REQ ? 0 : 1;
}

int llc_sap_ev_rx_ui(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_SAP_EV_TYPE_PDU && LLC_PDU_IS_CMD(pdu) &&
	       LLC_PDU_TYPE_IS_U(pdu) &&
	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_UI ? 0 : 1;
}

int llc_sap_ev_unitdata_req(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);

	return ev->type == LLC_SAP_EV_TYPE_PRIM &&
	       ev->prim == LLC_DATAUNIT_PRIM &&
	       ev->prim_type == LLC_PRIM_TYPE_REQ ? 0 : 1;

}

int llc_sap_ev_xid_req(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);

	return ev->type == LLC_SAP_EV_TYPE_PRIM &&
	       ev->prim == LLC_XID_PRIM &&
	       ev->prim_type == LLC_PRIM_TYPE_REQ ? 0 : 1;
}

int llc_sap_ev_rx_xid_c(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_SAP_EV_TYPE_PDU && LLC_PDU_IS_CMD(pdu) &&
	       LLC_PDU_TYPE_IS_U(pdu) &&
	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID ? 0 : 1;
}

int llc_sap_ev_rx_xid_r(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_SAP_EV_TYPE_PDU && LLC_PDU_IS_RSP(pdu) &&
	       LLC_PDU_TYPE_IS_U(pdu) &&
	       LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_XID ? 0 : 1;
}

int llc_sap_ev_test_req(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);

	return ev->type == LLC_SAP_EV_TYPE_PRIM &&
	       ev->prim == LLC_TEST_PRIM &&
	       ev->prim_type == LLC_PRIM_TYPE_REQ ? 0 : 1;
}

int llc_sap_ev_rx_test_c(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_SAP_EV_TYPE_PDU && LLC_PDU_IS_CMD(pdu) &&
	       LLC_PDU_TYPE_IS_U(pdu) &&
	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST ? 0 : 1;
}

int llc_sap_ev_rx_test_r(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_SAP_EV_TYPE_PDU && LLC_PDU_IS_RSP(pdu) &&
	       LLC_PDU_TYPE_IS_U(pdu) &&
	       LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_TEST ? 0 : 1;
}

int llc_sap_ev_deactivation_req(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_sap_state_ev *ev = llc_sap_ev(skb);

	return ev->type == LLC_SAP_EV_TYPE_SIMPLE &&
	       ev->prim_type == LLC_SAP_EV_DEACTIVATION_REQ ? 0 : 1;
}
><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/sound/soc/samsung/smartq_wm8987.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/sound/soc/samsung/smartq_wm8987.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/sound/soc/samsung/smartq_wm8987.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>sound/soc/samsung/smartq_wm8987.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/samsung/smartq_wm8987.c?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/sound/soc/samsung/smartq_wm8987.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 'sound/soc/samsung/smartq_wm8987.c')</div><table summary='diffstat' class='diffstat'>