/* AFS network device helpers
 *
 * Copyright (c) 2007 Patrick McHardy <kaber@trash.net>
 */

#include <linux/string.h>
#include <linux/rtnetlink.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <net/net_namespace.h>
#include "internal.h"

/*
 * get a MAC address from a random ethernet interface that has a real one
 * - the buffer will normally be 6 bytes in size
 */
int afs_get_MAC_address(u8 *mac, size_t maclen)
{
	struct net_device *dev;
	int ret = -ENODEV;

	BUG_ON(maclen != ETH_ALEN);

	rtnl_lock();
	dev = __dev_getfirstbyhwtype(&init_net, ARPHRD_ETHER);
	if (dev) {
		memcpy(mac, dev->dev_addr, maclen);
		ret = 0;
	}
	rtnl_unlock();
	return ret;
}

/*
 * get a list of this system's interface IPv4 addresses, netmasks and MTUs
 * - maxbufs must be at least 1
 * - returns the number of interface records in the buffer
 */
int afs_get_ipv4_interfaces(struct afs_interface *bufs, size_t maxbufs,
			    bool wantloopback)
{
	struct net_device *dev;
	struct in_device *idev;
	int n = 0;

	ASSERT(maxbufs > 0);

	rtnl_lock();
	for_each_netdev(&init_net, dev) {
		if (dev->type == ARPHRD_LOOPBACK && !wantloopback)
			continue;
		idev = __in_dev_get_rtnl(dev);
		if (!idev)
			continue;
		for_primary_ifa(idev) {
			bufs[n].address.s_addr = ifa->ifa_address;
			bufs[n].netmask.s_addr = ifa->ifa_mask;
			bufs[n].mtu = dev->mtu;
			n++;
			if (n >= maxbufs)
				goto out;
		} endfor_ifa(idev);
	}
out:
	rtnl_unlock();
	return n;
}
ight'>Tobias Klauser</td></tr></table>
<table class='tabs'><tr><td>
<a href='/cgit.cgi/linux/net-next.git/'>summary</a><a href='/cgit.cgi/linux/net-next.git/refs/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>refs</a><a href='/cgit.cgi/linux/net-next.git/log/net/l3mdev/Kconfig'>log</a><a href='/cgit.cgi/linux/net-next.git/tree/net/l3mdev/Kconfig?id=966d2b04e070bc040319aaebfec09e0144dc3341'>tree</a><a class='active' href='/cgit.cgi/linux/net-next.git/commit/net/l3mdev/Kconfig?id=966d2b04e070bc040319aaebfec09e0144dc3341'>commit</a><a href='/cgit.cgi/linux/net-next.git/diff/net/l3mdev/Kconfig?id=966d2b04e070bc040319aaebfec09e0144dc3341'>diff</a></td><td class='form'><form class='right' method='get' action='/cgit.cgi/linux/net-next.git/log/net/l3mdev/Kconfig'>
<input type='hidden' name='id' value='966d2b04e070bc040319aaebfec09e0144dc3341'/><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/commit/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net?id=966d2b04e070bc040319aaebfec09e0144dc3341'>net</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/l3mdev?id=966d2b04e070bc040319aaebfec09e0144dc3341'>l3mdev</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/l3mdev/Kconfig?id=966d2b04e070bc040319aaebfec09e0144dc3341'>Kconfig</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/net/l3mdev/Kconfig?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/l3mdev/Kconfig?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/l3mdev/Kconfig?id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/l3mdev/Kconfig</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/l3mdev/Kconfig?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/l3mdev/Kconfig?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/l3mdev/Kconfig')</div><table summary='diffstat' class='diffstat'>