While testing the virtio-net driver on KVM with TSO I noticed
that TSO performance with a 1500 MTU is significantly worse
compared to the performance of non-TSO with a 16436 MTU. The
packet dump shows that most of the packets sent are smaller
than a page.
Looking at the code this actually is quite obvious as it always
stop extending the packet if it's the first packet yet to be
sent and if it's larger than the MSS. Since each extension is
bound by the page size, this means that (given a 1500 MTU) we're
very unlikely to construct packets greater than a page, provided
that the receiver and the path is fast enough so that packets can
always be sent immediately.
The fix is also quite obvious. The push calls inside the loop
is just an optimisation so that we don't end up doing all the
sending at the end of the loop. Therefore there is no specific
reason why it has to do so at MSS boundaries. For TSO, the
most natural extension of this optimisation is to do the pushing
once the skb exceeds the TSO size goal.
This is what the patch does and testing with KVM shows that the
TSO performance with a 1500 MTU easily surpasses that of a 16436
MTU and indeed the packet sizes sent are generally larger than
16436.
I don't see any obvious downsides for slower peers or connections,
but it would be prudent to test this extensively to ensure that
those cases don't regress.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Been seeing occasional panics in my testing of 2.6.25-rc in ip_defrag.
Offending line in ip_defrag is here:
net = skb->dev->nd_net
where dev is NULL. Bisected the problem down to commit
ac18e7509e ([NETNS][FRAGS]: Make the
inet_frag_queue lookup work in namespaces).
Below patch (idea from Patrick McHardy) fixes the problem for me.
Signed-off-by: Phil Oester <kernel@linuxace.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
When selecting a new window, tcp_select_window() tries not to shrink
the offered window by using the maximum of the remaining offered window
size and the newly calculated window size. The newly calculated window
size is always a multiple of the window scaling factor, the remaining
window size however might not be since it depends on rcv_wup/rcv_nxt.
This means we're effectively shrinking the window when scaling it down.
The dump below shows the problem (scaling factor 2^7):
- Window size of 557 (71296) is advertised, up to 3111907257:
IP 172.2.2.3.33000 > 172.2.2.2.33000: . ack 3111835961 win 557 <...>
- New window size of 514 (65792) is advertised, up to 3111907217, 40 bytes
below the last end:
IP 172.2.2.3.33000 > 172.2.2.2.33000: . 3113575668:3113577116(1448) ack 3111841425 win 514 <...>
The number 40 results from downscaling the remaining window:
3111907257 - 3111841425 = 65832
65832 / 2^7 = 514
65832 % 2^7 = 40
If the sender uses up the entire window before it is shrunk, this can have
chaotic effects on the connection. When sending ACKs, tcp_acceptable_seq()
will notice that the window has been shrunk since tcp_wnd_end() is before
tp->snd_nxt, which makes it choose tcp_wnd_end() as sequence number.
This will fail the receivers checks in tcp_sequence() however since it
is before it's tp->rcv_wup, making it respond with a dupack.
If both sides are in this condition, this leads to a constant flood of
ACKs until the connection times out.
Make sure the window is never shrunk by aligning the remaining window to
the window scaling factor.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
If a rule using ipt_recent is created with a hit count greater than
ip_pkt_list_tot, the rule will never match as it cannot keep track
of enough timestamps. This patch makes ipt_recent refuse to create such
rules.
With ip_pkt_list_tot's default value of 20, the following can be used
to reproduce the problem.
nc -u -l 0.0.0.0 1234 &
for i in `seq 1 100`; do echo $i | nc -w 1 -u 127.0.0.1 1234; done
This limits it to 20 packets:
iptables -A OUTPUT -p udp --dport 1234 -m recent --set --name test \
--rsource
iptables -A OUTPUT -p udp --dport 1234 -m recent --update --seconds \
60 --hitcount 20 --name test --rsource -j DROP
While this is unlimited:
iptables -A OUTPUT -p udp --dport 1234 -m recent --set --name test \
--rsource
iptables -A OUTPUT -p udp --dport 1234 -m recent --update --seconds \
60 --hitcount 21 --name test --rsource -j DROP
With the patch the second rule-set will throw an EINVAL.
Reported-by: Sean Kennedy <skennedy@vcn.com>
Signed-off-by: Daniel Hokka Zakrisson <daniel@hozac.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
With TSO it was possible to send past the receiver window when the skb
to be sent was the last in the write queue while the receiver window
is the limiting factor. One can notice that there's a loophole in the
tcp_mss_split_point that lacked a receiver window check for the
tcp_write_queue_tail() if also cwnd was smaller than the full skb.
Noticed by Thomas Gleixner <tglx@linutronix.de> in form of "Treason
uncloaked! Peer ... shrinks window .... Repaired." messages (the peer
didn't actually shrink its window as the message suggests, we had just
sent something past it without a permission to do so).
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
From: Stephen Hemminger <shemminger@linux-foundation.org>
Based upon a patch by Marcel Wappler:
This patch fixes a DHCP issue of the kernel: some DHCP servers
(i.e. in the Linksys WRT54Gv5) are very strict about the contents
of the DHCPDISCOVER packet they receive from clients.
Table 5 in RFC2131 page 36 requests the fields 'ciaddr' and
'siaddr' MUST be set to '0'. These DHCP servers ignore Linux
kernel's DHCP discovery packets with these two fields set to
'255.255.255.255' (in contrast to popular DHCP clients, such as
'dhclient' or 'udhcpc'). This leads to a not booting system.
Signed-off-by: David S. Miller <davem@davemloft.net>
Now the ESP uses the AEAD interface even for algorithms which are
not combined mode, we need to select CONFIG_CRYPTO_AUTHENC as
otherwise only combined mode algorithms will work.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
It makes fackets_out to grow too slowly compared with the
real write queue.
This shouldn't cause those BUG_TRAP(packets <= tp->packets_out)
to trigger but how knows how such inconsistent fackets_out
affects here and there around TCP when everything is nowadays
assuming accurate fackets_out. So lets see if this silences
them all.
Reported by Guillaume Chazarain <guichaz@gmail.com>.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use proc_create() to make sure that ->proc_fops be setup before gluing
PDE to main tree.
Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Because we use shared tfm objects in order to conserve memory,
(each tfm requires 128K of vmalloc memory), BH needs to be turned
off on output as that can occur in process context.
Previously this was done implicitly by the xfrm output code.
That was lost when it became lockless. So we need to add the
BH disabling to IPComp directly.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Four tunnel drivers (ip_gre, ipip, ip6_tunnel and sit) can receive a
pre-defined name for a device from the userspace. Since these drivers
call the register_netdevice() (rtnl_lock, is held), which does _not_
generate the device's name, this name may contain a '%' character.
Not sure how bad is this to have a device with a '%' in its name, but
all the other places either use the register_netdev(), which call the
dev_alloc_name(), or explicitly call the dev_alloc_name() before
registering, i.e. do not allow for such names.
This had to be prior to the commit 34cc7b, but I forgot to number the
patches and this one got lost, sorry.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This bug did bite at least one user, who did have to resort to rebooting
the system after an "ifconfig eth0 127.0.0.1" typo.
Deleting the address and adding a new is a less intrusive workaround.
But I still beleive this is a bug that should be fixed. Some way or
another.
Another possibility would be to remove the scope mangling based on
address. This will always be incomplete (are 127/8 the only address
space with host scope requirements?)
We set the scope to RT_SCOPE_HOST if an IPv4 interface is configured
with a loopback address (127/8). The scope is never reset, and will
remain set to RT_SCOPE_HOST after changing the address. This patch
resets the scope if the address is changed again, to restore normal
functionality.
Signed-off-by: Bjorn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use the added dev_alloc_name() call to create tunnel device name,
rather than iterate in a hand-made loop with an artificial limit.
Thanks Patrick for noticing this.
[ The way this works is, when the device is actually registered,
the generic code noticed the '%' in the name and invokes
dev_alloc_name() to fully resolve the name. -DaveM ]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
http://bugzilla.kernel.org/show_bug.cgi?id=9920
The function skb_make_writable returns true or false.
Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
As reported by Tomas Simonaitis <tomas.simonaitis@gmail.com>,
inserting new data in skbs queued over {ip,ip6,nfnetlink}_queue
triggers a SKB_LINEAR_ASSERT in skb_put().
Going back through the git history, it seems this bug is present since
at least 2.6.12-rc2, probably even since the removal of
skb_linearize() for netfilter.
Linearize non-linear skbs through skb_copy_expand() when enlarging
them. Tested by Thomas, fixes bugzilla #9933.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Unless I miss a guaranteed relation between between "f" and
"new_fa->fa_info" this patch is required for fixing a NULL dereference
introduced by commit a6501e080c ("[IPV4]
FIB_HASH: Reduce memory needs and speedup lookups") and spotted by the
Coverity checker.
Eric Dumazet says:
Hum, you are right, kmem_cache_free() doesnt allow a NULL
object, like kfree() does.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Make the indented lines aligned in the output (not in the code).
Signed-off-by: Uwe Kleine-Koenig <Uwe.Kleine-Koenig@digi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commit 69cc64d8d9.
It causes recursive locking in IPV6 because unlike other
neighbour layer clients, it even needs neighbour cache
entries to send neighbour soliciation messages :-(
We'll have to find another way to fix this race.
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch removes the no longer used EXPORT_SYMBOL(inet_listen_wlock).
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch removes the unused EXPORT_SYMBOL_GPL(__inet_hash_connect).
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Al Viro spotted a bogus use of u64 on the input sequence number which
is big-endian. This patch fixes it by giving the input sequence number
its own member in the xfrm_skb_cb structure.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Frank Blaschka provided the bug report and the initial suggested fix
for this bug. He also validated this version of this fix.
The problem is that the access to neigh->arp_queue is inconsistent, we
grab references when dropping the lock lock to call
neigh->ops->solicit() but this does not prevent other threads of
control from trying to send out that packet at the same time causing
corruptions because both code paths believe they have exclusive access
to the skb.
The best option seems to be to hold the write lock on neigh->lock
during the ->solicit() call. I looked at all of the ndisc_ops
implementations and this seems workable. The only case that needs
special care is the IPV4 ARP implementation of arp_solicit(). It
wants to take neigh->lock as a reader to protect the header entry in
neigh->ha during the emission of the soliciation. We can simply
remove the read lock calls to take care of that since holding the lock
as a writer at the caller providers a superset of the protection
afforded by the existing read locking.
The rest of the ->solicit() implementations don't care whether the
neigh is locked or not.
Signed-off-by: David S. Miller <davem@davemloft.net>
Use key/offset caching to change /proc/net/route (use by iputils route)
from O(n^2) to O(n). This improves performance from 30sec with 160,000
routes to 1sec.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This fixes possible problems when trie_firstleaf() returns NULL
to trie_leafindex().
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Various RFCs have all sorts of things to say about the CS field of the
DSCP value. In particular they try to make the distinction between
values that should be used by "user applications" and things like
routing daemons.
This seems to have influenced the CAP_NET_ADMIN check which exists for
IP_TOS socket option settings, but in fact it has an off-by-one error
so it wasn't allowing CS5 which is meant for "user applications" as
well.
Further adding to the inconsistency and brokenness here, IPV6 does not
validate the DSCP values specified for the IPV6_TCLASS socket option.
The real actual uses of these TOS values are system specific in the
final analysis, and these RFC recommendations are just that, "a
recommendation". In fact the standards very purposefully use
"SHOULD" and "SHOULD NOT" when describing how these values can be
used.
In the final analysis the only clean way to provide consistency here
is to remove the CAP_NET_ADMIN check. The alternatives just don't
work out:
1) If we add the CAP_NET_ADMIN check to ipv6, this can break existing
setups.
2) If we just fix the off-by-one error in the class comparison in
IPV4, certain DSCP values can be used in IPV6 but not IPV4 by
default. So people will just ask for a sysctl asking to
override that.
I checked several other freely available kernel trees and they
do not make any privilege checks in this area like we do. For
the BSD stacks, this goes back all the way to Stevens Volume 2
and beyond.
Signed-off-by: David S. Miller <davem@davemloft.net>
ip_route_me_harder() may call ip_route_input() with skbs that don't
have skb->dev set for skbs rerouted in LOCAL_OUT and TCP resets
generated by the REJECT target, resulting in a crash when dereferencing
skb->dev->nd_net. Since ip_route_input() has an input device argument,
it seems correct to use that one anyway.
Bug introduced in b5921910a1 (Routing cache virtualization).
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The ->move operation has two bugs:
- It is called with the same extension as source and destination,
so it doesn't update the new extension.
- The address of the old extension is calculated incorrectly,
instead of (void *)ct->ext + ct->ext->offset[i] it uses
ct->ext + ct->ext->offset[i].
Fixes a crash on x86_64 reported by Chuck Ebbert <cebbert@redhat.com>
and Thomas Woerner <twoerner@redhat.com>.
Tested-by: Thomas Woerner <twoerner@redhat.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
No available servers is more an error message than something informational. It
should also be rate-limited, else we're going to flood our logs on a busy
director, if all real servers are out of order with a weight of zero.
Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a new set of configuration functions to the NetLabel/LSM API so that
LSMs can perform their own configuration of the NetLabel subsystem without
relying on assistance from userspace.
Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Somewhere along the development of my ICMP relookup patch the header
length check went AWOL on the non-IPsec path. This patch restores the
check.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
The port offset calculations depend on the protocol family, but, as
Adrian noticed, I broke this logic with the commit
5ee31fc1ec
[INET]: Consolidate inet(6)_hash_connect.
Return this logic back, by passing the port offset directly into the
consolidated function.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Noticed-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The line in the /proc/net/fib_trie for route with TOS specified
- has extra \n at the end
- does not have a space after route scope
like below.
|-- 1.1.1.1
/32 universe UNICASTtos =1
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
A bug every C programmer makes at some point in time...
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This way we can remove TCP and DCCP specific versions of
sk->sk_prot->get_port: both v4 and v6 use inet_csk_get_port
sk->sk_prot->hash: inet_hash is directly used, only v6 need
a specific version to deal with mapped sockets
sk->sk_prot->unhash: both v4 and v6 use inet_hash directly
struct inet_connection_sock_af_ops also gets a new member, bind_conflict, so
that inet_csk_get_port can find the per family routine.
Now only the lookup routines receive as a parameter a struct inet_hashtable.
With this we further reuse code, reducing the difference among INET transport
protocols.
Eventually work has to be done on UDP and SCTP to make them share this
infrastructure and get as a bonus inet_diag interfaces so that iproute can be
used with these protocols.
net-2.6/net/ipv4/inet_hashtables.c:
struct proto | +8
struct inet_connection_sock_af_ops | +8
2 structs changed
__inet_hash_nolisten | +18
__inet_hash | -210
inet_put_port | +8
inet_bind_bucket_create | +1
__inet_hash_connect | -8
5 functions changed, 27 bytes added, 218 bytes removed, diff: -191
net-2.6/net/core/sock.c:
proto_seq_show | +3
1 function changed, 3 bytes added, diff: +3
net-2.6/net/ipv4/inet_connection_sock.c:
inet_csk_get_port | +15
1 function changed, 15 bytes added, diff: +15
net-2.6/net/ipv4/tcp.c:
tcp_set_state | -7
1 function changed, 7 bytes removed, diff: -7
net-2.6/net/ipv4/tcp_ipv4.c:
tcp_v4_get_port | -31
tcp_v4_hash | -48
tcp_v4_destroy_sock | -7
tcp_v4_syn_recv_sock | -2
tcp_unhash | -179
5 functions changed, 267 bytes removed, diff: -267
net-2.6/net/ipv6/inet6_hashtables.c:
__inet6_hash | +8
1 function changed, 8 bytes added, diff: +8
net-2.6/net/ipv4/inet_hashtables.c:
inet_unhash | +190
inet_hash | +242
2 functions changed, 432 bytes added, diff: +432
vmlinux:
16 functions changed, 485 bytes added, 492 bytes removed, diff: -7
/home/acme/git/net-2.6/net/ipv6/tcp_ipv6.c:
tcp_v6_get_port | -31
tcp_v6_hash | -7
tcp_v6_syn_recv_sock | -9
3 functions changed, 47 bytes removed, diff: -47
/home/acme/git/net-2.6/net/dccp/proto.c:
dccp_destroy_sock | -7
dccp_unhash | -179
dccp_hash | -49
dccp_set_state | -7
dccp_done | +1
5 functions changed, 1 bytes added, 242 bytes removed, diff: -241
/home/acme/git/net-2.6/net/dccp/ipv4.c:
dccp_v4_get_port | -31
dccp_v4_request_recv_sock | -2
2 functions changed, 33 bytes removed, diff: -33
/home/acme/git/net-2.6/net/dccp/ipv6.c:
dccp_v6_get_port | -31
dccp_v6_hash | -7
dccp_v6_request_recv_sock | +5
3 functions changed, 5 bytes added, 38 bytes removed, diff: -33
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The namespace is not available in the fib_sync_down_addr, add it as a
parameter.
Looking up a device by the pointer to it is OK. Looking up using a
result from fib_trie/fib_hash table lookup is also safe. No need to
fix that at all. So, just fix lookup by address and insertion to the
hash table path.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is required to make fib_info lookups namespace aware. In the
other case initial namespace devices are marked as dead in the local
routing table during other namespace stop.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
fib_sync_down can be called with an address and with a device. In
reality it is called either with address OR with a device. The
codepath inside is completely different, so lets separate it into two
calls for these two cases.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The namespace is available when required except rtm_to_ifaddr. Add
namespace argument to it.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove error code assignment inside brackets on failure. The code
looks better if the error is assigned before condition check. Also,
the compiler treats this better.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
net->ipv4.fib_table_hash is not freed when fib4_rules_init failed.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch removes the no longer used
EXPORT_SYMBOL(sysctl_tcp_tso_win_divisor).
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
struct ipv4_devconf can now become static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Current ip route cache implementation is not suited to large caches.
We can consume a lot of CPU when cache must be invalidated, since we
currently need to evict all cache entries, and this eviction is
sometimes asynchronous. min_delay & max_delay can somewhat control this
asynchronism behavior, but whole thing is a kludge, regularly triggering
infamous soft lockup messages. When entries are still in use, this also
consumes a lot of ram, filling dst_garbage.list.
A better scheme is to use a generation identifier on each entry,
so that cache invalidation can be performed by changing the table
identifier, without having to scan all entries.
No more delayed flushing, no more stalling when secret_interval expires.
Invalidated entries will then be freed at GC time (controled by
ip_rt_gc_timeout or stress), or when an invalidated entry is found
in a chain when an insert is done.
Thus we keep a normal equilibrium.
This patch :
- renames rt_hash_rnd to rt_genid (and makes it an atomic_t)
- Adds a new rt_genid field to 'struct rtable' (filling a hole on 64bit)
- Checks entry->rt_genid at appropriate places :
In strategy_allowed_congestion_control of the 2.6.24 kernel, when
sysctl_string return 1 on success,it should call
tcp_set_allowed_congestion_control to set the allowed congestion
control.But, it don't. the sysctl_string return 1 on success,
otherwise return negative, never return 0.The patch fix the problem.
Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
