With subfacets, we'd expect megaflow updates message to carry
the original micro flow. If not, EINVAL is returned and kernel
logs an error message. Now that the user space subfacet layer is
removed, it is expected that flow updates can arrive with a
micro flow other than the original. Change the return code to
EEXIST and remove the kernel error log message.
Reported-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
commit 43d4be9cb5 (openvswitch: Allow user space
to announce ability to accept unaligned Netlink messages) introduced
OVS_DP_ATTR_USER_FEATURES netlink attribute in datapath responses,
but the attribute size was not taken into account in ovs_dp_cmd_msg_size().
Signed-off-by: Daniele Di Proietto <daniele.di.proietto@gmail.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Both mega flow mask's reference counter and per flow table mask list
should only be accessed when holding ovs_mutex() lock. However
this is not true with ovs_flow_table_flush(). The patch fixes this bug.
Reported-by: Joe Stringer <joestringer@nicira.com>
Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
While the zerocopy method is correctly omitted if user space
does not support unaligned Netlink messages. The attribute is
still not padded correctly as skb_zerocopy() will not ensure
padding and the attribute size is no longer pre calculated
though nla_reserve() which ensured padding previously.
This patch applies appropriate padding if a linear data copy
was performed in skb_zerocopy().
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Several functions and datastructures could be local
Found with 'make namespacecheck'
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Jesse Gross <jesse@nicira.com>
The copy & csum optimization is no longer present with zerocopy
enabled. Compute the checksum in skb_gso_segment() directly by
dropping the HW CSUM capability from the features passed in.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Use of skb_zerocopy() can avoid the expensive call to memcpy()
when copying the packet data into the Netlink skb. Completes
checksum through skb_checksum_help() if not already done in
GSO segmentation.
Zerocopy is only performed if user space supported unaligned
Netlink messages. memory mapped netlink i/o is preferred over
zerocopy if it is set up.
Cost of upcall is significantly reduced from:
+ 7.48% vhost-8471 [k] memcpy
+ 5.57% ovs-vswitchd [k] memcpy
+ 2.81% vhost-8471 [k] csum_partial_copy_generic
to:
+ 5.72% ovs-vswitchd [k] memcpy
+ 3.32% vhost-5153 [k] memcpy
+ 0.68% vhost-5153 [k] skb_zerocopy
(megaflows disabled)
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Allows removing the net and dp_ifindex argument and simplify the
code.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Drop user features if an outdated user space instance that does not
understand the concept of user_features attempted to create a new
datapath.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
With mega flow implementation ovs flow can be shared between
multiple CPUs which makes stats updates highly contended
operation. This patch uses per-CPU stats in cases where a flow
is likely to be shared (if there is a wildcard in the 5-tuple
and therefore likely to be spread by RSS). In other situations,
it uses the current strategy, saving memory and allocation time.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Flow lookup can happen either in packet processing context or userspace
context but it was annotated as requiring RCU read lock to be held. This
also allows OVS mutex to be held without causing warnings.
Reported-by: Justin Pettit <jpettit@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Reviewed-by: Thomas Graf <tgraf@redhat.com>
API changes only for code readability. No functional chnages.
This patch removes the underscored version. Added a new API
ovs_flow_tbl_lookup_stats() that returns the n_mask_hits.
Reported by: Ben Pfaff <blp@nicira.com>
Reviewed-by: Thomas Graf <tgraf@redhat.com>
Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Pull networking fixes from David Miller:
"Mostly these are fixes for fallout due to merge window changes, as
well as cures for problems that have been with us for a much longer
period of time"
1) Johannes Berg noticed two major deficiencies in our genetlink
registration. Some genetlink protocols we passing in constant
counts for their ops array rather than something like
ARRAY_SIZE(ops) or similar. Also, some genetlink protocols were
using fixed IDs for their multicast groups.
We have to retain these fixed IDs to keep existing userland tools
working, but reserve them so that other multicast groups used by
other protocols can not possibly conflict.
In dealing with these two problems, we actually now use less state
management for genetlink operations and multicast groups.
2) When configuring interface hardware timestamping, fix several
drivers that simply do not validate that the hwtstamp_config value
is one the driver actually supports. From Ben Hutchings.
3) Invalid memory references in mwifiex driver, from Amitkumar Karwar.
4) In dev_forward_skb(), set the skb->protocol in the right order
relative to skb_scrub_packet(). From Alexei Starovoitov.
5) Bridge erroneously fails to use the proper wrapper functions to make
calls to netdev_ops->ndo_vlan_rx_{add,kill}_vid. Fix from Toshiaki
Makita.
6) When detaching a bridge port, make sure to flush all VLAN IDs to
prevent them from leaking, also from Toshiaki Makita.
7) Put in a compromise for TCP Small Queues so that deep queued devices
that delay TX reclaim non-trivially don't have such a performance
decrease. One particularly problematic area is 802.11 AMPDU in
wireless. From Eric Dumazet.
8) Fix crashes in tcp_fastopen_cache_get(), we can see NULL socket dsts
here. Fix from Eric Dumzaet, reported by Dave Jones.
9) Fix use after free in ipv6 SIT driver, from Willem de Bruijn.
10) When computing mergeable buffer sizes, virtio-net fails to take the
virtio-net header into account. From Michael Dalton.
11) Fix seqlock deadlock in ip4_datagram_connect() wrt. statistic
bumping, this one has been with us for a while. From Eric Dumazet.
12) Fix NULL deref in the new TIPC fragmentation handling, from Erik
Hugne.
13) 6lowpan bit used for traffic classification was wrong, from Jukka
Rissanen.
14) macvlan has the same issue as normal vlans did wrt. propagating LRO
disabling down to the real device, fix it the same way. From Michal
Kubecek.
15) CPSW driver needs to soft reset all slaves during suspend, from
Daniel Mack.
16) Fix small frame pacing in FQ packet scheduler, from Eric Dumazet.
17) The xen-netfront RX buffer refill timer isn't properly scheduled on
partial RX allocation success, from Ma JieYue.
18) When ipv6 ping protocol support was added, the AF_INET6 protocol
initialization cleanup path on failure was borked a little. Fix
from Vlad Yasevich.
19) If a socket disconnects during a read/recvmsg/recvfrom/etc that
blocks we can do the wrong thing with the msg_name we write back to
userspace. From Hannes Frederic Sowa. There is another fix in the
works from Hannes which will prevent future problems of this nature.
20) Fix route leak in VTI tunnel transmit, from Fan Du.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (106 commits)
genetlink: make multicast groups const, prevent abuse
genetlink: pass family to functions using groups
genetlink: add and use genl_set_err()
genetlink: remove family pointer from genl_multicast_group
genetlink: remove genl_unregister_mc_group()
hsr: don't call genl_unregister_mc_group()
quota/genetlink: use proper genetlink multicast APIs
drop_monitor/genetlink: use proper genetlink multicast APIs
genetlink: only pass array to genl_register_family_with_ops()
tcp: don't update snd_nxt, when a socket is switched from repair mode
atm: idt77252: fix dev refcnt leak
xfrm: Release dst if this dst is improper for vti tunnel
netlink: fix documentation typo in netlink_set_err()
be2net: Delete secondary unicast MAC addresses during be_close
be2net: Fix unconditional enabling of Rx interface options
net, virtio_net: replace the magic value
ping: prevent NULL pointer dereference on write to msg_name
bnx2x: Prevent "timeout waiting for state X"
bnx2x: prevent CFC attention
bnx2x: Prevent panic during DMAE timeout
...
Register generic netlink multicast groups as an array with
the family and give them contiguous group IDs. Then instead
of passing the global group ID to the various functions that
send messages, pass the ID relative to the family - for most
families that's just 0 because the only have one group.
This avoids the list_head and ID in each group, adding a new
field for the mcast group ID offset to the family.
At the same time, this allows us to prevent abusing groups
again like the quota and dropmon code did, since we can now
check that a family only uses a group it owns.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This doesn't really change anything, but prepares for the
next patch that will change the APIs to pass the group ID
within the family, rather than the global group ID.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a static inline to generic netlink to wrap netlink_set_err()
to make it easier to use here - use it in openvswitch (the only
generic netlink user of netlink_set_err()).
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As suggested by David Miller, make genl_register_family_with_ops()
a macro and pass only the array, evaluating ARRAY_SIZE() in the
macro, this is a little safer.
The openvswitch has some indirection, assing ops/n_ops directly in
that code. This might ultimately just assign the pointers in the
family initializations, saving the struct genl_family_and_ops and
code (once mcast groups are handled differently.)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now that genl_ops are no longer modified in place when
registering, they can be made const. This patch was done
mostly with spatch:
@@
identifier ops;
@@
+const
struct genl_ops ops[] = {
...
};
(except the struct thing in net/openvswitch/datapath.c)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull core locking changes from Ingo Molnar:
"The biggest changes:
- add lockdep support for seqcount/seqlocks structures, this
unearthed both bugs and required extra annotation.
- move the various kernel locking primitives to the new
kernel/locking/ directory"
* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
block: Use u64_stats_init() to initialize seqcounts
locking/lockdep: Mark __lockdep_count_forward_deps() as static
lockdep/proc: Fix lock-time avg computation
locking/doc: Update references to kernel/mutex.c
ipv6: Fix possible ipv6 seqlock deadlock
cpuset: Fix potential deadlock w/ set_mems_allowed
seqcount: Add lockdep functionality to seqcount/seqlock structures
net: Explicitly initialize u64_stats_sync structures for lockdep
locking: Move the percpu-rwsem code to kernel/locking/
locking: Move the lglocks code to kernel/locking/
locking: Move the rwsem code to kernel/locking/
locking: Move the rtmutex code to kernel/locking/
locking: Move the semaphore core to kernel/locking/
locking: Move the spinlock code to kernel/locking/
locking: Move the lockdep code to kernel/locking/
locking: Move the mutex code to kernel/locking/
hung_task debugging: Add tracepoint to report the hang
x86/locking/kconfig: Update paravirt spinlock Kconfig description
lockstat: Report avg wait and hold times
lockdep, x86/alternatives: Drop ancient lockdep fixup message
...
In order to enable lockdep on seqcount/seqlock structures, we
must explicitly initialize any locks.
The u64_stats_sync structure, uses a seqcount, and thus we need
to introduce a u64_stats_init() function and use it to initialize
the structure.
This unfortunately adds a lot of fairly trivial initialization code
to a number of drivers. But the benefit of ensuring correctness makes
this worth while.
Because these changes are required for lockdep to be enabled, and the
changes are quite trivial, I've not yet split this patch out into 30-some
separate patches, as I figured it would be better to get the various
maintainers thoughts on how to best merge this change along with
the seqcount lockdep enablement.
Feedback would be appreciated!
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: James Morris <jmorris@namei.org>
Cc: Jesse Gross <jesse@nicira.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Mirko Lindner <mlindner@marvell.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Roger Luethi <rl@hellgate.ch>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Simon Horman <horms@verge.net.au>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Wensong Zhang <wensong@linux-vs.org>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/1381186321-4906-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Widen TCP flags handling from 7 bits (uint8_t) to 12 bits (uint16_t).
The kernel interface remains at 8 bits, which makes no functional
difference now, as none of the higher bits is currently of interest
to the userspace.
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Collect mega flow mask stats. ovs-dpctl show command can be used to
display them for debugging and performance tuning.
Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Hides mega-flow implementation in flow_table.c rather than
datapath.c.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
ovs-flow rehash does not touch mega flow list. Following patch
moves it dp struct datapath. Avoid one extra indirection for
accessing mega-flow list head on every packet receive.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Over the time datapath.c and flow.c has became pretty large files.
Following patch restructures functionality of component into three
different components:
flow.c: contains flow extract.
flow_netlink.c: netlink flow api.
flow_table.c: flow table api.
This patch restructures code without changing logic.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Rehashing in ovs-workqueue can cause ovs-mutex lock contentions
in case of heavy flow setups where both needs ovs-mutex. So by
moving rehashing to flow-setup we can eliminate contention.
This also simplify ovs locking and reduces dependence on
workqueue.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
This patch adds support for rewriting SCTP src,dst ports similar to the
functionality already available for TCP/UDP.
Rewriting SCTP ports is expensive due to double-recalculation of the
SCTP checksums; this is performed to ensure that packets traversing OVS
with invalid checksums will continue to the destination with any
checksum corruption intact.
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Add wildcarded flow support in kernel datapath.
Wildcarded flow can improve OVS flow set up performance by avoid sending
matching new flows to the user space program. The exact performance boost
will largely dependent on wildcarded flow hit rate.
In case all new flows hits wildcard flows, the flow set up rate is
within 5% of that of linux bridge module.
Pravin has made significant contributions to this patch. Including API
clean ups and bug fixes.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
RCUfy dp-dump operation which is already read-only. This
makes all ovs dump operations lockless.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Flow dump operation is read-only operation. There is no need to
take ovs-lock. Following patch use rcu-lock for dumping flows.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
git silently included an extra hunk in vport_cmd_set() during
automatic merging. This code is unreachable so it does not actually
introduce a problem but it is clearly incorrect.
Signed-off-by: Jesse Gross <jesse@nicira.com>
Following patch adds start offset for sw_flow-key, so that we can
skip tunneling information in key for non-tunnel flows.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add ovs tunnel interface for set tunnel action for userspace.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rather than validating actions and then copying all actiaons
in one block, following patch does same operation in single pass.
This validate and copy action one by one. This is required for
ovs tunneling patch.
This patch does not change any functionality.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is not functional change, this is just code cleanup.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
It is an error to try to change the type of a vport using the set
command. However, while we check that this is an error, we still
proceed to allocate memory which then gets freed immediately.
This stops processing after noticing the error, which does not
actually fix a bug but is more correct.
Signed-off-by: Jesse Gross <jesse@nicira.com>
The only user is get_dpifindex(), no need to redirect via the port
operations.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
OVS locking was recently changed to have private OVS lock which
simplified overall locking. Therefore there is no need to have
another global genl lock to protect OVS data structures. Following
patch uses of parallel_ops genl family for OVS. This also allows
more granual OVS locking using ovs_mutex for protecting OVS data
structures, which gives more concurrencey. E.g multiple genl
operations OVS_PACKET_CMD_EXECUTE can run in parallel, etc.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Conflicts:
drivers/net/ethernet/emulex/benet/be_main.c
drivers/net/ethernet/intel/igb/igb_main.c
drivers/net/wireless/brcm80211/brcmsmac/mac80211_if.c
include/net/scm.h
net/batman-adv/routing.c
net/ipv4/tcp_input.c
The e{uid,gid} --> {uid,gid} credentials fix conflicted with the
cleanup in net-next to now pass cred structs around.
The be2net driver had a bug fix in 'net' that overlapped with the VLAN
interface changes by Patrick McHardy in net-next.
An IGB conflict existed because in 'net' the build_skb() support was
reverted, and in 'net-next' there was a comment style fix within that
code.
Several batman-adv conflicts were resolved by making sure that all
calls to batadv_is_my_mac() are changed to have a new bat_priv first
argument.
Eric Dumazet's TS ECR fix in TCP in 'net' conflicted with the F-RTO
rewrite in 'net-next', mostly overlapping changes.
Thanks to Stephen Rothwell and Antonio Quartulli for help with several
of these merge resolutions.
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a protocol argument to the VLAN packet tagging functions. In case of HW
tagging, we need that protocol available in the ndo_start_xmit functions,
so it is stored in a new field in the skb. The new field fits into a hole
(on 64 bit) and doesn't increase the sks's size.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently OVS uses combination of genl and rtnl lock to protect
datapath state. This was done due to networking stack locking.
But this has complicated locking and there are few lock ordering
issues with new tunneling protocols.
Following patch simplifies locking by introducing new ovs mutex
and now this lock is used to protect entire ovs state.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Kills the FLOW_BUFSIZE constant which needs to be calculated manually
and replaces it with key_attr_size() based on nla_total_size().
Calculates the size of datapath messages instead of relying on
NLMSG_DEFAULT_SIZE and moves the existing message size calculations
into own functions for clarity.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Less error prone as it takes into account the length of both the
destination buffer and the source attribute and documents when
data is copied from an attribute.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Specifying the minimal length in the policy makes it reuseable
and documents the interface.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Add a new constant ETH_P_802_3_MIN, the minimum ethernet type for
an 802.3 frame. Frames with a lower value in the ethernet type field
are Ethernet II.
Also update all the users of this value that David Miller and
I could find to use the new constant.
Also correct a bug in util.c. The comparison with ETH_P_802_3_MIN
should be >= not >.
As suggested by Jesse Gross.
Compile tested only.
Cc: David Miller <davem@davemloft.net>
Cc: Jesse Gross <jesse@nicira.com>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: John W. Linville <linville@tuxdriver.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Bart De Schuymer <bart.de.schuymer@pandora.be>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: linux-bluetooth@vger.kernel.org
Cc: netfilter-devel@vger.kernel.org
Cc: bridge@lists.linux-foundation.org
Cc: linux-wireless@vger.kernel.org
Cc: linux1394-devel@lists.sourceforge.net
Cc: linux-media@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: dev@openvswitch.org
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Allocation of the Netlink notification skb can potentially fail
after changing vport configuration. In general, we try to avoid
this by undoing any change we made but that is difficult for existing
objects. This avoids the problem by preallocating the buffer (which
is fixed size).
Signed-off-by: Jesse Gross <jesse@nicira.com>
Andy Zhou