/*
 * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
 * Copyright (C) 2015-2016 Samsung Electronics
 *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
 *               Krzysztof Opasiak <k.opasiak@samsung.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/device.h>
#include <linux/list.h>
#include <linux/module.h>

#include "vudc.h"

static unsigned int vudc_number = 1;

module_param_named(num, vudc_number, uint, S_IRUGO);
MODULE_PARM_DESC(num, "number of emulated controllers");

static struct platform_driver vudc_driver = {
	.probe		= vudc_probe,
	.remove		= vudc_remove,
	.driver		= {
		.name	= GADGET_NAME,
	},
};

static struct list_head vudc_devices = LIST_HEAD_INIT(vudc_devices);

static int __init init(void)
{
	int retval = -ENOMEM;
	int i;
	struct vudc_device *udc_dev = NULL, *udc_dev2 = NULL;

	if (usb_disabled())
		return -ENODEV;

	if (vudc_number < 1) {
		pr_err("Number of emulated UDC must be no less than 1");
		return -EINVAL;
	}

	retval = platform_driver_register(&vudc_driver);
	if (retval < 0)
		goto out;

	for (i = 0; i < vudc_number; i++) {
		udc_dev = alloc_vudc_device(i);
		if (!udc_dev) {
			retval = -ENOMEM;
			goto cleanup;
		}

		retval = platform_device_add(udc_dev->pdev);
		if (retval < 0) {
			put_vudc_device(udc_dev);
			goto cleanup;
		}

		list_add_tail(&udc_dev->dev_entry, &vudc_devices);
		if (!platform_get_drvdata(udc_dev->pdev)) {
			/*
			 * The udc was added successfully but its probe
			 * function failed for some reason.
			 */
			retval = -EINVAL;
			goto cleanup;
		}
	}
	goto out;

cleanup:
	list_for_each_entry_safe(udc_dev, udc_dev2, &vudc_devices, dev_entry) {
		list_del(&udc_dev->dev_entry);
		platform_device_del(udc_dev->pdev);
		put_vudc_device(udc_dev);
	}

	platform_driver_unregister(&vudc_driver);
out:
	return retval;
}
module_init(init);

static void __exit cleanup(void)
{
	struct vudc_device *udc_dev = NULL, *udc_dev2 = NULL;

	list_for_each_entry_safe(udc_dev, udc_dev2, &vudc_devices, dev_entry) {
		list_del(&udc_dev->dev_entry);
		platform_device_unregister(udc_dev->pdev);
		put_vudc_device(udc_dev);
	}
	platform_driver_unregister(&vudc_driver);
}
module_exit(cleanup);

MODULE_DESCRIPTION("USB over IP Device Controller");
MODULE_AUTHOR("Krzysztof Opasiak, Karol Kosik, Igor Kotrasinski");
MODULE_LICENSE("GPL");
-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>net</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>ipv6</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6/icmp.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>icmp.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/ipv6/icmp.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/ipv6/icmp.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/ipv6/icmp.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/ipv6/icmp.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6/icmp.c?h=nds-private-remove&amp;id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/ipv6/icmp.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/ipv6/icmp.c')</div><table summary='diffstat' class='diffstat'>