Commit Graph

386 Commits

Author SHA1 Message Date
Slava Shwartsman
186058782a ipoib: Notify on modify QP failure only when relevant
Modify QP can fail and it can be acceptable, like when moving from RST to
ERR state, all the rest are not acceptable and a message to the log
should be printed.

The current code prints on all failures and many messages like:
"Failed to modify QP to ERROR state" appear, even when supported by the
state machine of the QP object.

Linux commit:
5dc78ad1904db597bdb4427f3ead437aae86f54c

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:27:17 +00:00
Slava Shwartsman
a061f0eb65 ipoib: increase the non-cm queue length
When a packet needs fragmentation, it might generate more than 3 fragments.
With the queue length 3, all fragments are generated faster than the
queue is drained, which effectively drops fourth and later fragments on
the floor.

Submitted by:   kib@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:26:47 +00:00
Slava Shwartsman
d705eff259 ipoib: Don't do a light flush when MTU is unchanged.
When changing the MTU of ibX network interfaces, check that the MTU was really
changed before requesting an update of the multicast rules. Else we might go
into an infinite loop joining and leaving ibX multicast groups towards the
opensm master interface.

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:26:17 +00:00
Slava Shwartsman
099ad46e81 ipoib: correct setting MTU from inside ipoib(4).
It is not enough to set ifnet->if_mtu to change the interface MTU.
System saves the MTU for route in the radix tree, and route cache keeps
the interface MTU as well. Since addition of the multicast group causes
recalculation of MTU, even bringing the interface up changes MTU from
4042 to 1500, which makes the system configuration inconsistent. Worse,
ip_output() prefers route MTU over interface MTU, so large packets are
not fragmented and dropped on floor.

Fix it for ipoib(4) using the same approach (or hack) as was applied
for it_tun/if_tap in r339012.  Thanks to bz@ for giving the hint.

Submitted by:   kib@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:25:47 +00:00
Slava Shwartsman
e13619b68b ibcore: Fix clearing of bound device interface.
Binding to a loopback device is not allowed. Make sure the destination
device address is global by clearing the bound device interface.
Only do this conditionally, else link local addresses won't work.

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:25:13 +00:00
Slava Shwartsman
a9c20af23d ibcore: ip6_dev_find() needs to know the scope ID.
Else the wrong network device can be returned for link-local addresses.

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:24:43 +00:00
Slava Shwartsman
5ace00dffe ibcore: Fix sleeping in atomic when RoCE is used
A couple of places in the CM do

    spin_lock_irq(&cm_id_priv->lock);
    ...
    if (cm_alloc_response_msg(work->port, work->mad_recv_wc, &msg))

However when the underlying transport is RoCE, this leads to a sleeping function
being called with the lock held - the callchain is

    cm_alloc_response_msg() ->
      ib_create_ah_from_wc() ->
        ib_init_ah_from_wc() ->
          rdma_addr_find_l2_eth_by_grh() ->
            rdma_resolve_ip()

and rdma_resolve_ip() starts out by doing

    req = kzalloc(sizeof *req, GFP_KERNEL);

not to mention rdma_addr_find_l2_eth_by_grh() doing

    wait_for_completion(&ctx.comp);

to wait for the task that rdma_resolve_ip() queues up.

Fix this by moving the AH creation out of the lock.

Linux commit:
c76161181193985087cd716fdf69b5cb6cf9ee85

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:24:12 +00:00
Slava Shwartsman
0231669450 ibcore: Add missing unref of netdevice.
Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:23:44 +00:00
Slava Shwartsman
ae8534ca28 ibcore: Fix loopback with rdma-cm.
Trying to validate loopback fails because rtalloc1() resolves system
local addresses to the loopback network interface, lo0. Fix this by
explicitly checking for loopback during validation of the source
and destination network address. If the source address belongs to
a local network interface and is equal to the destination address,
there is no need to run the destination address through rtalloc1().

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:23:14 +00:00
Slava Shwartsman
f3cf3b7e84 ibcore: Make sure all VNETs are scanned for VLAN interfaces.
The master network interface and the VLANs may reside in different VNETs.
Make sure that all VNETs are searched when scanning for GID entries.

Submitted by:   netapp
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:22:43 +00:00
Slava Shwartsman
af60974508 ibcore: Always check return value from ib_init_ah_from_wc().
This prevents code from accepting RoCEv1 connections when
only ROCEv2 is enabled and vice versa.

Linux commit:
0c4386ec77cfcd0ccbdbe8c2e67dd3a49b2a4c7f

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:22:07 +00:00
Slava Shwartsman
9fc9810098 ibcore: Add missing check for failure.
Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:21:20 +00:00
Slava Shwartsman
33d7f9b8fb ibcore: Fix an array index check
The array ib_mad_mgmt_class_table.method_table has MAX_MGMT_CLASS
(80) elements. Hence compare the array index with that value instead
of with IB_MGMT_MAX_METHODS (128). This patch avoids that Coverity
reports the following:

Overrunning array class->method_table of 80 8-byte elements at element index 127
(byte offset 1016) using index convert_mgmt_class(mad_hdr->mgmt_class)
(which evaluates to 127).

Linux commit:
2fe2f378dd45847d2643638c07a7658822087836

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:20:51 +00:00
Slava Shwartsman
fe521b4443 ibcore: Check ib_find_pkey() return value.
Linux commit:
d3a2418ee36a59bc02e9d454723f3175dcf4bfd9

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:20:22 +00:00
Slava Shwartsman
4aa5230dc5 ibcore: Add support for IB_SPEED_HDR in sysfs rate printout.
Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:19:52 +00:00
Slava Shwartsman
475c8de7bf ibcore: Don't access invalid port.
The port number in the listen_id_priv has been observed to be zero which
means no port has been selected. The current code lacks a check for invalid
port number.

Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:19:21 +00:00
Slava Shwartsman
4b9b52a1bd ibcore: Discard unused error codes.
Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:18:50 +00:00
Slava Shwartsman
f628150b6c ibcore: Make sure GID index variable gets initialized.
Submitted by:   hselasky@
Approved by:    hselasky (mentor)
MFC after:      1 week
Sponsored by:   Mellanox Technologies
2018-12-05 13:18:20 +00:00
Mark Johnston
79db6fe7aa Plug some networking sysctl leaks.
Various network protocol sysctl handlers were not zero-filling their
output buffers and thus would export uninitialized stack memory to
userland.  Fix a number of such handlers.

Reported by:	Thomas Barabosch, Fraunhofer FKIE
Reviewed by:	tuexen
MFC after:	3 days
Security:	kernel memory disclosure
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D18301
2018-11-22 20:49:41 +00:00
Hans Petter Selasky
7877f59352 Introduce and use sgid_index in CM requests in ibcore.
For RoCE, when CM requests are received for RC and UD connections,
netdevice of the incoming request is unavailable. Because of that CM
requests are always forwarded to init_net namespace.

Now that we have the GID index available, introduce SGID index in
incoming CM requests and refer to the netdevice of it.

While at it fix some incorrect uses of init_net and make sure
the rdma_create_id() function stores the VNET it is passed.

Based on linux commit:
cee104334c98dd04e9dd4d9a4fa4784f7f6aada9

MFC after:		3 days
Approved by:		re (gjb)
Sponsored by:		Mellanox Technologies
2018-09-09 07:20:15 +00:00
Hans Petter Selasky
86156495f4 Implement get network interface by params function in ipoib.
Also fix the validate_ipv4_net_dev() and validate_ipv6_net_dev() functions
which had source and destination addresses swapped, and didn't set the
scope ID for IPv6 link-local addresses.

This allows applications like krping to work using IPoIB devices.

MFC after:		3 days
Approved by:		re (gjb)
Sponsored by:		Mellanox Technologies
2018-09-07 18:05:09 +00:00
Slava Shwartsman
b4df6efb4e ibcore: Fix endless loop in searching for matching VLAN device
In r337943 ifnet's if_pcp was set to the PCP value in use
instead of IFNET_PCP_NONE.
Current ibcore code assumes that if_pcp is IFNET_PCP_NONE with
VLAN interfaces so it can identify prio-tagged traffic.
Fix that by explicitly verifying that that the if_type is IFT_ETHER
and not IFT_L2VLAN.

MFC after:      3 days
Approved by:    re (Marius), hselasky (mentor), kib (mentor)
Sponsored by:   Mellanox Technologies
2018-09-06 12:26:57 +00:00
Hans Petter Selasky
fb11674d30 Only NULL check the VNET pointer when VIMAGE is enabled in ibcore.
Else a NULL VNET pointer should be ignored. This fixes address resolving
when VIMAGE is disabled.

MFC after:		3 days
Sponsored by:		Mellanox Technologies
2018-07-31 11:23:44 +00:00
Hans Petter Selasky
cda1e10ca0 Use __FBSDID() for RCS tags in ibcore.
MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:47:14 +00:00
Hans Petter Selasky
8ac2952539 Remove blank line.
MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:44:16 +00:00
Hans Petter Selasky
1bebf70fe7 Add support for IPv6 multicast in ibcore.
This change allows us to join IPv6 multicast networks.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:37:16 +00:00
Hans Petter Selasky
c68cb3a60a Add support for RoCEv2 multicast in ibcore.
When creating address handle from multicast GID, set MAC according to
the appropriate formula instead of searching for it in the GID table:
- For IPv4 multicast GID use ip_eth_mc_map().
- For IPv6 multicast GID use ipv6_eth_mc_map().

Linux commit:
9636a56fa864464896bf7d1272c701f2b9a57737

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:36:04 +00:00
Hans Petter Selasky
e3e6820f69 Honor return status of ib_init_ah_from_mcmember() in ibcore.
The return status of ib_init_ah_from_mcmember() is ignored by
cma_ib_mc_handler().  Honor it and return error event if ah attribute
initialization failed.

Linux commit:
6d337179f28cc50ddd7e224f677b4cda70b275fc

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:34:29 +00:00
Hans Petter Selasky
0f2b4041fe Honor port_num while resolving GID for IB link layer in ibcore.
ah_attr contains the port number to which cm_id is bound. However, while
searching for GID table for matching GID entry, the port number is
ignored.

This could cause the wrong GID to be used when the ah_attr is converted to
an AH.

Linux commit:
563c4ba3bd2b8b0b21c65669ec2226b1cfa1138b

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:33:20 +00:00
Hans Petter Selasky
56acbf0932 Set IPv4 TOS and IPv6 traffic class field for RoCEv2 traffic in ibcore.
The current implementation assumes a static mapping between
the TOS bits and the priority code point, PCP bits.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:32:09 +00:00
Hans Petter Selasky
02825401aa Fix for loopback detection in address resolve logic in ibcore.
When a loopback address is detected use the network interface which
has the loopback flag set to trigger loopback logic in address resolve.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:30:32 +00:00
Hans Petter Selasky
f736cb92cf Check port number supplied by user verbs cmds in ibcore.
The ib_uverbs_create_ah() ind ib_uverbs_modify_qp() calls receive
the port number from user input as part of its attributes and assumes
it is valid. Down on the stack, that parameter is used to access kernel
data structures.  If the value is invalid, the kernel accesses memory
it should not.  To prevent this, verify the port number before using it.

Linux commit:
5ecce4c9b17bed4dc9cb58bfb10447307569b77b
a62ab66b13a0f9bcb17b7b761f6670941ed5cd62
5a7a88f1b488e4ee49eb3d5b82612d4d9ffdf2c3

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:29:14 +00:00
Hans Petter Selasky
56326b4755 Depend on IPv6 stack to resolve link local address for RoCEv2 in ibcore.
RoCEv1 does not use the IPv6 stack to resolve the link local DGID since it
uses GID address. It forms the DMAC directly from the DGID.

Linux commit:
56d0a7d9a0f045ee27a001762deac28c7d28e2e4

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:27:31 +00:00
Hans Petter Selasky
df9bb49b66 Fix kernel crash during fail to initialize device in ibcore.
This patch fixes the kernel crash that occurs during ib_dealloc_device()
called due to provider driver fails with an error after
ib_alloc_device() and before it can register using ib_register_device().

This crashed seen in tha lab as below which can occur with any IB device
which fails to perform its device initialization before invoking
ib_register_device().

This patch avoids touching cache and port immutable structures if device
is not yet initialized.
It also releases related memory when cache and port immutable data
structure initialization fails during register_device() state.

Linux commit:
4be3a4fa51f432ef045546d16f25c68a1ab525b9

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:26:09 +00:00
Hans Petter Selasky
855ad7cf39 Check AF family prior resolving address and introduce safer rdma_addr_size() variants in ibcore.
Garbage supplied by user will cause to UCMA module provide zero
memory size for memcpy(), because it wasn't checked, it will
produce unpredictable results in rdma_resolve_addr().

There are several places in the ucma ABI where userspace can pass in a
sockaddr but set the address family to AF_IB.  When that happens,
rdma_addr_size() will return a size bigger than sizeof struct sockaddr_in6,
and the ucma kernel code might end up copying past the end of a buffer
not sized for a struct sockaddr_ib.

Fix this by introducing new variants
    int rdma_addr_size_in6(struct sockaddr_in6 *addr);
    int rdma_addr_size_kss(struct __kernel_sockaddr_storage *addr);

that are type-safe for the types used in the ucma ABI and return 0 if the
size computed is bigger than the size of the type passed in.  We can use
these new variants to check what size userspace has passed in before
copying any addresses.

Linux commit:
2975d5de6428ff6d9317e9948f0968f7d42e5d74
09abfe7b5b2f442a85f4c4d59ecf582ad76088d7
84652aefb347297aa08e91e283adf7b18f77c2d5

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:24:39 +00:00
Hans Petter Selasky
41decb450f Check for a cm_id->device in all user calls that need it in ibcore.
This was done by auditing all callers of ucma_get_ctx and switching the
ones that unconditionally touch ->device to ucma_get_ctx_dev. This covers
a little less than  half of the call sites.

The 11 remaining call sites to ucma_get_ctx() were manually audited.

Linux commit:
4b658d1bbc16605330694bb3ef2570c465ef383d
8b77586bd8fe600d97f922c79f7222c46f37c118

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:22:26 +00:00
Hans Petter Selasky
89a0812fa6 Restore initialisation of ctx->uid in ucma_create_id() in ibcore.
This fixes a regression issue after r336373.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:21:05 +00:00
Hans Petter Selasky
083cdbac35 Fix kernel panic while using XRC_TGT QP type in ibcore.
Attempt to modify XRC_TGT QP type from the user space (ibv_xsrq_pingpong
invocation) will trigger the following kernel panic. It is caused by the
fact that such QPs missed uobject initialization.

Linux commit:
f45765872e7aae7b81feb3044aaf9886b21885ef

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:18:16 +00:00
Hans Petter Selasky
765bd83cca Fix NULL pointer dereference during device removal in ibcore.
As part of ib_uverbs_remove_one which might be triggered upon
reset flow, we trigger IB_EVENT_DEVICE_FATAL event to userspace
application.
If device was removed after uverbs fd was opened but before
ib_uverbs_get_context was called, the event file will be accessed
before it was allocated, result in NULL pointer dereference:

Linux commit:
870201f95fcbd19538aef630393fe9d583eff82e

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:16:54 +00:00
Hans Petter Selasky
ed222171a9 Fix access to non-initialized CM_ID object in ibcore.
The attempt to join multicast group without ensuring that CMA device
exists will lead to the following crash reported by syzkaller.

Linux commit:
7688f2c3bbf55e52388e37ac5d63ca471a7712e1

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:15:50 +00:00
Hans Petter Selasky
91f0e6e1d8 Avoid that ib_drain_qp() triggers an out-of-bounds stack access in ibcore.
Linux commit:
a1ae7d0345edd593d6725d3218434d903a0af95d

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:14:20 +00:00
Hans Petter Selasky
7477a89ae2 Ensure that CM_ID exists prior to access it in ibcore.
Prior to access UCMA commands, the context should be initialized
and connected to CM_ID with ucma_create_id(). In case user skips
this step, he can provide non-valid ctx without CM_ID and cause
to multiple NULL dereferences.

Also there are situations where the create_id can be raced with
other user access, ensure that the context is only shared to
other threads once it is fully initialized to avoid the races.

Linux commit:
e8980d67d6017c8eee8f9c35f782c4bd68e004c9

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:13:11 +00:00
Hans Petter Selasky
f4546fa376 Add support for prio-tagged traffic for RDMA in ibcore.
When receiving a PCP change all GID entries are reloaded.
This ensures the relevant GID entries use prio tagging,
by setting VLAN present and VLAN ID to zero.

The priority for prio tagged traffic is set using the regular
rdma_set_service_type() function.

Fake the real network device to have a VLAN ID of zero
when prio tagging is enabled. This is logic is hidden inside
the rdma_vlan_dev_vlan_id() function which must always be used
to retrieve the VLAN ID throughout all of ibcore and the
infiniband network drivers.

The VLAN presence information then propagates through all
of ibcore and so incoming connections will have the VLAN
bit set. The incoming VLAN ID is then checked against the
return value of rdma_vlan_dev_vlan_id().

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:11:53 +00:00
Hans Petter Selasky
682bd3fe12 Set default GID type as RoCE when resolving RoCE route in ibcore.
cma_iboe_set_mgid() is updated to reflect the RoCEv2 GID check.

Linux commit:
5c181bda77f409d89ad513528eccac5f3a416474

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:09:17 +00:00
Hans Petter Selasky
b70db3278f Set RoCEv2 MGID according to spec in ibcore.
RoCEv2 Annex states that for RoCEv2 over IPv4, the corresponding
IPv4 address is encoded into the GID according to the following rule:
GID= :ffff:<IPv4 address>

Remove the 0xff0e prefix for RoCEv2 packets with IPv4 and leave it
zeroed and change rdma_is_multicast_addr() to consider the new logic.

Linux commit:
be1d325a335840a86c133a56c6a911c368bac0fd
1c3aea2bc8f0b2e5b57375ead40457ff75a3a2ec

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:07:36 +00:00
Hans Petter Selasky
71698382e3 For multicast functions in ibcore, verify that LIDs are multicast LIDs.
The Infiniband spec defines "A multicast address is defined by a
MGID and a MLID" (section 10.5).

Add check to verify that the MLID value is in the correct address
range.

RoCE Annex (A16.9.10/11) declares that during attach (detach) QP to a
multicast group, if the QP is associated with a RoCE port, the
multicast group MLID is unused and is ignored.

During attach or detach multicast, when the QP is associated with a
port, it is enough to check the port's link layer and validate the
LID only if it is Infiniband. Otherwise, avoid validating the
multicast LID.

Linux commit:
8561eae60ff9417a50fa1fb2b83ae950dc5c1e21
5236333592244557a19694a51337df6ac018f0a7

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:04:36 +00:00
Hans Petter Selasky
fed17c5852 Fix for RDMA loopback over VLAN in ibcore.
Implement a more generic solution for detecting loopback.
The problem was that the default netdevice was resolved
for loopback also when VLAN was used. Use real network
device instead of loopback device for bound device
interface.

How to test:
ucmatose -b 127.0.0.1 -p 20090
ucmatose -s 5.6.5.1 -p 20090

Note that RDMA treats the IPv4 and IPv6 loopback
addresses like any address.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 09:02:29 +00:00
Hans Petter Selasky
f9899e4567 Add native FreeBSD support for multicast in ibcore.
This change adds support for registering multicast addresses,
both IPv4 and IPv6.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 08:59:34 +00:00
Hans Petter Selasky
7a658d6545 If the MGID/MLID pair is not on the list return an error in ibcore.
A list of MGID/MLID pairs is built when doing a multicast attach.  When
the multicast detach is called, the list is searched, and regardless of
the search outcome, the driver detach is called.

If an MGID/MLID pair is not on the list, driver detach should not be
called, and an error should be returned.  Calling the driver without
removing an MGID/MLID pair from the list can leave the core and driver
out of sync.

Linux commit:
20c7840a77ddcb2ed2fbd66e8197db2868495751

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 08:54:40 +00:00
Hans Petter Selasky
ef24f05897 Add lock to multicast handlers in ibcore.
When two handlers used the same object in the old schema, we blocked
the process in the kernel. The new schema just returns -EBUSY. This
could lead to different behaviour in applications between the old
schema and the new schema. In most cases, using such handlers
concurrently could lead to crashing the process. For example, if
thread A destroys a QP and thread B modifies it, we could have the
destruction happens before the modification. In this case, we are
accessing freed memory which could lead to crashing the process.
This is true for most cases. However, attaching and detaching
a multicast address from QP concurrently is safe. Therefore, we
preserve the original behaviour by adding a lock there.

Linux commit:
f48b726920d96dcd1860df06143bdea7d6d7dcc3

MFC after:		1 week
Sponsored by:		Mellanox Technologies
2018-07-17 08:52:29 +00:00