/*
 *  net/dccp/sysctl.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 v2
 *	as published by the Free Software Foundation.
 */

#include <linux/mm.h>
#include <linux/sysctl.h>
#include "dccp.h"
#include "feat.h"

#ifndef CONFIG_SYSCTL
#error This file should not be compiled without CONFIG_SYSCTL defined
#endif

/* Boundary values */
static int		zero     = 0,
			one      = 1,
			u8_max   = 0xFF;
static unsigned long	seqw_min = DCCPF_SEQ_WMIN,
			seqw_max = 0xFFFFFFFF;		/* maximum on 32 bit */

static struct ctl_table dccp_default_table[] = {
	{
		.procname	= "seq_window",
		.data		= &sysctl_dccp_sequence_window,
		.maxlen		= sizeof(sysctl_dccp_sequence_window),
		.mode		= 0644,
		.proc_handler	= proc_doulongvec_minmax,
		.extra1		= &seqw_min,		/* RFC 4340, 7.5.2 */
		.extra2		= &seqw_max,
	},
	{
		.procname	= "rx_ccid",
		.data		= &sysctl_dccp_rx_ccid,
		.maxlen		= sizeof(sysctl_dccp_rx_ccid),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &zero,
		.extra2		= &u8_max,		/* RFC 4340, 10. */
	},
	{
		.procname	= "tx_ccid",
		.data		= &sysctl_dccp_tx_ccid,
		.maxlen		= sizeof(sysctl_dccp_tx_ccid),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &zero,
		.extra2		= &u8_max,		/* RFC 4340, 10. */
	},
	{
		.procname	= "request_retries",
		.data		= &sysctl_dccp_request_retries,
		.maxlen		= sizeof(sysctl_dccp_request_retries),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &one,
		.extra2		= &u8_max,
	},
	{
		.procname	= "retries1",
		.data		= &sysctl_dccp_retries1,
		.maxlen		= sizeof(sysctl_dccp_retries1),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &zero,
		.extra2		= &u8_max,
	},
	{
		.procname	= "retries2",
		.data		= &sysctl_dccp_retries2,
		.maxlen		= sizeof(sysctl_dccp_retries2),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &zero,
		.extra2		= &u8_max,
	},
	{
		.procname	= "tx_qlen",
		.data		= &sysctl_dccp_tx_qlen,
		.maxlen		= sizeof(sysctl_dccp_tx_qlen),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &zero,
	},
	{
		.procname	= "sync_ratelimit",
		.data		= &sysctl_dccp_sync_ratelimit,
		.maxlen		= sizeof(sysctl_dccp_sync_ratelimit),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_ms_jiffies,
	},

	{ }
};

static struct ctl_table_header *dccp_table_header;

int __init dccp_sysctl_init(void)
{
	dccp_table_header = register_net_sysctl(&init_net, "net/dccp/default",
			dccp_default_table);

	return dccp_table_header != NULL ? 0 : -ENOMEM;
}

void dccp_sysctl_exit(void)
{
	if (dccp_table_header != NULL) {
		unregister_net_sysctl_table(dccp_table_header);
		dccp_table_header = NULL;
	}
}
e070bc040319aaebfec09e0144dc3341'>include</a>/<a href='/cgit.cgi/linux/net-next.git/commit/include/crypto?id=966d2b04e070bc040319aaebfec09e0144dc3341'>crypto</a>/<a href='/cgit.cgi/linux/net-next.git/commit/include/crypto/ghash.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>ghash.h</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/include/crypto/ghash.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/crypto/ghash.h?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/include/crypto/ghash.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>include/crypto/ghash.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/crypto/ghash.h?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/crypto/ghash.h?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 'include/crypto/ghash.h')</div><table summary='diffstat' class='diffstat'>