For HCAs that support checksum offload (ie that set IB_DEVICE_UD_IP_CSUM
in the device capabilities flags), have IPoIB set NETIF_F_IP_CSUM and
use the HCA to generate and verify IP checksums.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Commit 7143740d ("IPoIB: Add send gather support") made struct
ipoib_tx_buf significantly larger, since the mapping member changed
from a single u64 to an array with MAX_SKB_FRAGS + 1 entries. This
means that allocating tx_rings with kzalloc() may fail because there
is not enough contiguous memory for the new, much bigger size. Fix
this regression by allocating the rings with vmalloc() instead.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Commit 7143740d ("IPoIB: Add send gather support") made it possible
for tx_wr.num_sge to be != 1 -- this happens if send gather support is
enabled. However, the code in the connected mode post_send() function
assumes the old invariant, namely that tx_wr.num_sge is always 1. Fix
this by explicitly setting tx_wr.num_sge to 1 in the CM post_send().
Signed-off-by: Roland Dreier <rolandd@cisco.com>
When set_multicast_list() is called the multicast task is restarted
and the IPOIB_MCAST_STARTED bit is cleared. As a result for some
window of time, multicast packets are not transmitted nor queued but
rather dropped by ipoib_mcast_send(). These dropped packets are
painful in two cases:
- bonding fail-over which both calls set_multicast_list() on the new
active slave and sends Gratuitous ARP through that slave.
- IP_DROP_MEMBERSHIP code which both calls set_multicast_list() on the
device and issues IGMP leave.
In both these cases, depending on the scheduling of the IPoIB
multicast task, the packets would be dropped. As a result, in the
bonding case, the failover would not be detected by the peers until
their neighbour is renewed the neighbour (which takes a few tens of
seconds). In the IGMP case, the IP router doesn't get an IGMP leave
and would only learn on that from further probes on the group (also a
delay of at least a few tens of seconds).
Fix this by allowing transmission (or queuing) depending on the
IPOIB_FLAG_OPER_UP flag instead of the IPOIB_MCAST_STARTED flag.
Signed-off-by: Olga Shern <olgas@voltaire.com>
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Commit efcd9971 ("IPoIB/cm: Factor out ipoib_cm_free_rx_reap_list()")
introduced a bug in ipoib_cm_dev_stop() when the receive drain times
out. In that case, the function moves all the pending rx stuff into a
private list but then calls ipoib_cm_free_rx_reap_list(), which
handles a different list.
Fix this by moving everything to the rx_reap_list that will actually
get freed up.
This fixes <https://bugs.openfabrics.org/show_bug.cgi?id=906>.
Signed-off-by: Pradeep Satyanarayana <pradeeps@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
struct ipoib_cm_tx.ibwc is unused since commit 1b524963 ("IPoIB/cm:
Use common CQ for CM send completions"), so remove it.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
In P_Key event handling, if the old P_Key is no longer available, the
driver must call ipoib_ib_dev_stop() -- just as it does when the P_Key
is still available (see procedure __ipoib_ib_dev_flush()).
When a P_Key becomes available, the driver will perform ipoib_open(),
which assumes that the QP is in RESET, the cm_id has been
destroyed/deleted, etc. If ipoib_ib_dev_stop() is not called as
described above, then these assumptions will be false, and the attempt
to bring the interface up will fail.
Found by Mellanox QA.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This patch acts as a preparation for using checksum offload for IB
devices capable of inserting/verifying checksum in IP packets. The
patch does not actaully turn on NETIF_F_SG - we defer that to the
patches adding checksum offload capabilities.
We only add support for send gathers for datagram mode, since existing
HW does not support checksum offload on connected QPs.
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
All current InfiniBand devices can handle all DMA addresses, and it's
hard to imagine anyone would be silly enough to build a new device
that couldn't. Therefore, enable the NETIF_F_HIGHDMA feature for IPoIB.
This has no effect for no, but is needed when we enable gather/scatter
support and checksum stateless offloads.
Signed-off-by: Eli Cohen <eli@mellnaox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Commit 732a2170 ("IB/ipoib: Bound the net device to the ipoib_neigh
structue") left a misleading debug print (n->dev would be a bond
device only if boding is used). Clean it up.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Move up the code that checks for a situation where the remote GID
stored in the ipoib_neigh is different than the one present in the
neighbour (handle gratuitous ARP) or that a bonding fail over has
happened but the neighbour still has a pointer to an ipoib_neigh
created by a different device than the current slave. This will cause
the driver to apply the check also for connected mode neighbours.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
qdisc_run() now tests for queue_stopped() before calling
__qdisc_run(), and the same check is done in every iteration of
__qdisc_run(), so another check is not required in the driver xmit.
This means that ipoib_start_xmit() no longer needs to test
netif_queue_stopped(); the test was added to fix earlier kernels,
where the networking stack did not guarantee that the xmit method of
an LLTX driver would not be called after the queue was stopped, but
current kernels do provide this guarantee.
To validate, I put a debug in the TX_BUSY path which never hit with 64
threads running overnight exercising this code a few 100 million
times.
Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Some HCAs (such as ehca2) support SRQ, but only support fewer than 16 SG
entries for SRQs. Currently IPoIB/CM implicitly assumes all HCAs will
support 16 SG entries for SRQs (to handle a 64K MTU with 4K pages). This
patch removes that restriction by limiting the maximum MTU in connected
mode to what the maximum number of SRQ SG entries allows.
This patch addresses <https://bugs.openfabrics.org/show_bug.cgi?id=728>
Signed-off-by: Pradeep Satyanarayana <pradeeps@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
An IPoIB subnet on an IB fabric that spans multiple IB subnets can't
use link-local scope in multicast GIDs. The existing routines that
map IP/IPv6 multicast addresses into IB link-level addresses hard-code
the scope to link-local, and they also leave the partition key field
uninitialised. This patch adds a parameter (the link-level broadcast
address) to the mapping routines, allowing them to initialise both the
scope and the P_Key appropriately, and fixes up the call sites.
The next step will be to add a way to configure the scope for an IPoIB
interface.
Signed-off-by: Rolf Manderscheid <rvm@obsidianresearch.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Some IB adapters (notably IBM's eHCA) do not implement SRQs (shared
receive queues). The current IPoIB connected mode support only works
on devices that support SRQs.
Fix this by adding support for using the receive queue of each
connected mode receive QP. The disadvantage of this compared to using
an SRQ is that it means a full queue of receives must be posted for
each remote connected mode peer, which means that total memory usage
is potentially much higher than when using SRQs. To manage this, add
a new module parameter "max_nonsrq_conn_qp" that limits the number of
connections allowed per interface.
The rest of the changes are fairly straightforward: we use a table of
struct ipoib_cm_rx to hold all the active connections, and put the
table index of the connection in the high bits of receive WR IDs.
This is needed because we cannot rely on the struct ib_wc.qp field for
non-SRQ receive completions. Most of the rest of the changes just
test whether or not an SRQ is available, and post receives or find
received packets in the right place depending on the answer.
Cleaning up dead connections actually becomes simpler, because we do
not have to do the "last WQE reached" dance that is required to
destroy QPs attached to an SRQ. We just move the QP to the error
state and wait for all pending receives to be flushed.
Signed-off-by: Pradeep Satyanarayana <pradeeps@linux.vnet.ibm.com>
[ Completely rewritten and split up, based on Pradeep's work. Several
bugs fixed and no doubt several bugs introduced. - Roland ]
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Factor out the code for going through the rx_reap list of struct
ipoib_cm_rx and freeing each one. This consolidates the code
duplicated between ipoib_cm_dev_stop() and ipoib_cm_rx_reap() and
reduces the risk of error when adding additional accounting.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Factor out the code to create an SRQ and allocate the receive ring in
ipoib_cm_dev_init() into a new function ipoib_cm_create_srq(). This
will make the code neater when support for devices that don't implement
SRQs is added.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Factor out the code to unmap/free skbs and free the receive ring in
ipoib_cm_dev_cleanup() into a new function ipoib_cm_free_rx_ring().
This function will be called from a couple of other places when
support for devices that don't implement SRQs is added.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
If a port goes down, ipoib_ib_dev_down() is invoked -- which flushes
the mcasts (clearing priv->broadcast) and clearing the path record
cache. If ipoib_start_xmit() is then invoked (before the broadcast
group is rejoined), a kernel oops results from attempting to access
priv->broadcast, which is still unset.
Returning NULL from path_rec_create() if priv->broadcast is NULL is a
harmless way of bypassing the problem -- the offending packet is
simply discarded "without prejudice."
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Commit 1b524963 ("IPoIB/cm: Use common CQ for CM send completions")
changed how the high-order bits of work request IDs were used, which
had the effect that IPOIB_CM_RX_DRAIN_WRID was no longer handled as a
connected mode receive completion. This leads to the messages
ib1: cm send completion event with wrid 1073741823 (> 64)
ib1: RX drain timing out
when an interface with connected mode QPs is brought down. Fix this
by making sure that both IPOIB_OP_CM and IPOIB_OP_RECV are set in
IPOIB_CM_RX_DRAIN_WRID.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
mlx4_core: Increase command timeout for INIT_HCA to 10 seconds
IPoIB/cm: Use common CQ for CM send completions
IB/uverbs: Fix checking of userspace object ownership
IB/mlx4: Sanity check userspace send queue sizes
IPoIB: Rewrite "if (!likely(...))" as "if (unlikely(!(...)))"
IB/ehca: Enable large page MRs by default
IB/ehca: Change meaning of hca_cap_mr_pgsize
IB/ehca: Fix ehca_encode_hwpage_size() and alloc_fmr()
IB/ehca: Fix masking error in {,re}reg_phys_mr()
IB/ehca: Supply QP token for SRQ base QPs
IPoIB: Use round_jiffies() for ah_reap_task
RDMA/cma: Fix deadlock destroying listen requests
RDMA/cma: Add locking around QP accesses
IB/mthca: Avoid alignment traps when writing doorbells
mlx4_core: Kill mlx4_write64_raw()
Use the same CQ for CM send completions as for all other IPoIB
completions. This means all completions are processed via the same
NAPI polling routine. This should help reduce the number of
interrupts for bi-directional traffic (such as TCP) and fixes "driver
is hogging interrupts" errors reported for IPoIB send side, e.g.
<https://bugs.openfabrics.org/show_bug.cgi?id=508>
To do this, keep a per-interface counter of outstanding send WRs, and
stop the interface when this counter reaches the send queue size to
avoid CQ overruns.
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
It's too hard to figure out what "!likely(...)" really means, and who
knows how compilers interpret the hint.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Use round_jiffies() to align the 1 second ah_reap_task with other work
and potentially save power by sleeping cores for longer.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
When the bonding device senses a carrier loss of its active slave it replaces
that slave with a new one. In between the times when the carrier of an IPoIB
device goes down and ipoib_neigh is destroyed, it is possible that the
bonding driver will send a packet on a new slave that uses an old ipoib_neigh.
This patch detects and prevents this from happenning.
Signed-off-by: Moni Shoua <monis at voltaire.com>
Signed-off-by: Or Gerlitz <ogerlitz at voltaire.com>
Acked-by: Roland Dreier <rdreier@cisco.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
IPoIB uses a two layer neighboring scheme, such that for each struct neighbour
whose device is an ipoib one, there is a struct ipoib_neigh buddy which is
created on demand at the tx flow by an ipoib_neigh_alloc(skb->dst->neighbour)
call.
When using the bonding driver, neighbours are created by the net stack on behalf
of the bonding (master) device. On the tx flow the bonding code gets an skb such
that skb->dev points to the master device, it changes this skb to point on the
slave device and calls the slave hard_start_xmit function.
Under this scheme, ipoib_neigh_destructor assumption that for each struct
neighbour it gets, n->dev is an ipoib device and hence netdev_priv(n->dev)
can be casted to struct ipoib_dev_priv is buggy.
To fix it, this patch adds a dev field to struct ipoib_neigh which is used
instead of the struct neighbour dev one, when n->dev->flags has the
IFF_MASTER bit set.
Signed-off-by: Moni Shoua <monis at voltaire.com>
Signed-off-by: Or Gerlitz <ogerlitz at voltaire.com>
Acked-by: Roland Dreier <rdreier@cisco.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband: (87 commits)
mlx4_core: Fix section mismatches
IPoIB: Allow setting policy to ignore multicast groups
IB/mthca: Mark error paths as unlikely() in post_srq_recv functions
IB/ipath: Minor fix to ordering of freeing and zeroing of tid pages.
IB/ipath: Remove redundant link state checks
IB/ipath: Fix IB_EVENT_PORT_ERR event
IB/ipath: Better handling of unexpected GPIO interrupts
IB/ipath: Maintain active time on all chips
IB/ipath: Fix QHT7040 serial number check
IB/ipath: Indicate a couple of chip bugs to userspace
IB/ipath: iba6110 rev4 no longer needs recv header overrun workaround
IB/ipath: Use counters in ipath_poll and cleanup interrupts in ipath_close
IB/ipath: Remove duplicate copy of LMC
IB/ipath: Add ability to set the LMC via the sysfs debugging interface
IB/ipath: Optimize completion queue entry insertion and polling
IB/ipath: Implement IB_EVENT_QP_LAST_WQE_REACHED
IB/ipath: Generate flush CQE when QP is in error state
IB/ipath: Remove redundant code
IB/ipath: Future proof eeprom checksum code (contents reading)
IB/ipath: UC RDMA WRITE with IMMEDIATE doesn't send the immediate
...
The conversion to use netdevice internal stats left an unused variable
in ipoib_neigh_free(), since there's no longer any reason to get
netdev_priv() in order to increment dropped packets. Delete the
unused priv variable.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Use the stats member of struct netdevice in IPoIB, so we can save
memory by deleting the stats member of struct ipoib_dev_priv, and save
code by deleting ipoib_get_stats().
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since hardware header operations are part of the protocol class
not the device instance, make them into a separate object and
save memory.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
It's been a useless no-op for long enough in 2.6 so I figured it's time to
remove it. The number of people that could object because they're
maintaining unified 2.4 and 2.6 drivers is probably rather small.
[ Handled drivers added by netdev tree and some missed IRDA cases... -DaveM ]
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Several devices have multiple independant RX queues per net
device, and some have a single interrupt doorbell for several
queues.
In either case, it's easier to support layouts like that if the
structure representing the poll is independant from the net
device itself.
The signature of the ->poll() call back goes from:
int foo_poll(struct net_device *dev, int *budget)
to
int foo_poll(struct napi_struct *napi, int budget)
The caller is returned the number of RX packets processed (or
the number of "NAPI credits" consumed if you want to get
abstract). The callee no longer messes around bumping
dev->quota, *budget, etc. because that is all handled in the
caller upon return.
The napi_struct is to be embedded in the device driver private data
structures.
Furthermore, it is the driver's responsibility to disable all NAPI
instances in it's ->stop() device close handler. Since the
napi_struct is privatized into the driver's private data structures,
only the driver knows how to get at all of the napi_struct instances
it may have per-device.
With lots of help and suggestions from Rusty Russell, Roland Dreier,
Michael Chan, Jeff Garzik, and Jamal Hadi Salim.
Bug fixes from Thomas Graf, Roland Dreier, Peter Zijlstra,
Joseph Fannin, Scott Wood, Hans J. Koch, and Michael Chan.
[ Ported to current tree and all drivers converted. Integrated
Stephen's follow-on kerneldoc additions, and restored poll_list
handling to the old style to fix mutual exclusion issues. -DaveM ]
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The kernel IB stack allows (through the RDMA CM) userspace
applications to join and use multicast groups from the IPoIB MGID
range. This allows multicast traffic to be handled directly from
userspace QPs, without going through the kernel stack, which gives
better performance for some applications.
However, to fully interoperate with IP multicast, such userspace
applications need to participate in IGMP reports and queries, or else
routers may not forward the multicast traffic to the system where the
application is running. The simplest way to do this is to share the
kernel IGMP implementation by using the IP_ADD_MEMBERSHIP option to
join multicast groups that are being handled directly in userspace.
However, in such cases, the actual multicast traffic should not also
be handled by the IPoIB interface, because that would burn resources
handling multicast packets that will just be discarded in the kernel.
To handle this, this patch adds lookup on the database used for IB
multicast group reference counting when IPoIB is joining multicast
groups, and if a multicast group is already handled by user space,
then the IPoIB kernel driver ignores the group. This is controlled by
a per-interface policy flag. When the flag is set, IPoIB will not
join and attach its QP to a multicast group which already has an entry
in the database; when the flag is cleared, IPoIB will behave as before
this change.
For each IPoIB interface, the /sys/class/net/$intf/umcast attribute
controls the policy flag. The default value is off/0.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Make the way QP is being created in ipoib_cm_create_tx_qp()
consistent with ipoib_cm_create_rx_qp().
Signed-off-by: Dotan Barak <dotanb@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Clean up properly if ib_query_pkey() or ib_query_gid() fail.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
The current IPoIB code might process receive completions from
ipoib_drain_cq() when bringing down the interface. This could cause
packets to be passed up the stack without the device's poll method
being called. Avoid this by setting the status of any successful
completions to IB_WC_WR_FLUSH_ERR.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
ipoib_transport_dev_init() calls ipoib_cm_dev_init(), so it needs to
call ipoib_cm_dev_cleanup() to unwind that on the error path.
Found by Dotan Barak of Mellanox.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
The IB CM should include the HCA ACK delay when calculating the local
ACK timeout value to use for RC QPs. If the HCA ACK delay is large
enough relative to the packet life time, then if it is not taken into
account, the calculated timeout value ends up being too small, which
can result in "retry exceeded" errors.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
InfiniBand HCAs replicate multicast packets back to the QP that sent
them if that QP is attached to the destination multicast group. This
means that IPoIB multicasts are often replicated back to the receive
queue of the interface that generated them. To avoid confusing the
network stack, we drop these duplicates within the IPoIB driver.
However, there's no reason to free the skb that received the duplicate
and then immediately allocate a new skb to post to the receive queue.
We can be more efficient and just repost the same skb.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Fix
drivers/infiniband/ulp/ipoib/ipoib_cm.c:1151: warning: unused variable 'dev'
by getting rid of the variable dev, which is only used if CONFIG_IPV6
is enabled, and replacing the one use of it with the value it is
assigned, namely priv->dev.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Change Kconfig objects from "menu, config" into "menuconfig" so
that the user can disable the whole feature without having to
enter the menu first.
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
If a page can't be allocated for the frag list of a skb, the code to
unmap the partially allocated list is off by one. For exaple, if
'frags' equals one, i == 0, and the alloc_page() fails, then the old
loop would have unmapped mapping[1] which is uninitialized. The same
would happen if the call to ib_dma_map_page() failed.
Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Acked-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
IPoIB connected mode currently rejects a connection request unless the
supported MTU is >= the local netdevice MTU. This breaks
interoperability with implementations that might have tweaked
IPOIB_CM_MTU, and there's real no longer a reason to do so: this test
is just a leftover from when we did not tweak MTU per-connection. Fix
this by making the test as permissive as possible.
Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Fix a crasher bug in IPoIB CM: once a QP is in the RTR state, a
receive completion (or even an asynchronous error) might be observed
on this QP, so we have to initialize all of our receive data
structures before moving to the RTR state.
As an optimization (since modify_qp might take a long time), the
jiffies update done when moving RX to the passive_ids list is also
left in place to reduce the chance of the RX being misdetected as
stale.
This fixes bug <https://bugs.openfabrics.org/show_bug.cgi?id=662>.
Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
commit 518b1646 ("IPoIB/cm: Fix SRQ WR leak") introduced a severe
performance regression on Mellanox cards, because keeping a QP in the
error state for extended periods of time moves hardware to the slow
path (until the QP is destroyed). For example, MPI latency goes from
~3 usecs to ~7 usecs.
Fix this by posting a send WR on one of the QPs that are being
flushed, instead of using a separate drain QP that is kept in the
error state.
This fixes bug <https://bugs.openfabrics.org/show_bug.cgi?id=636>,
reported and bisected by Scott Weitzenkamp at Cisco and debugged by
Sasha Mikheev at Voltaire.
Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
