While cleaning neighs and there is a send-only mcast neigh, the driver
should wait to finish its join process before trying to remove it.

Without this patch, we will see messages like: "ipoib_mcast_leave on an
in-flight join" and unexpected results in the join_complete.
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>

The work mcast_task can re-queue itself, so instead of doing
cancel && flush_workqueue, that still can leave a queued task
on the air, use cancel_delayed_work_sync.

Also, no need to use lock over the cancel, the original lock was
due to bit assignment setting (IPOIB_MCAST_RUN) that is not in use
anymore.
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>

A potential race between light_event and interface restart
may attach multicast group to an already attached QP.

Scenario:
light_event flow goes through ipoib_mcast_dev_flush function,
if a context switch occurs before calling ipoib_mcast_remove_list,
then we may face a situation where the broadcast of the priv is null
and the corresponding QP is not detached yet.
If an "interface restart" runs during the previous context switch,
the following scenario occurs:
When the device goes up, ipoib_ib_dev_up function will be called,
it will send a new registration request to the broadcast group and then
attach the group to the QP that was not detached before.

     IPOIB_FLUSH_LIGHT                                          INTERFACE RESTART

    __ipoib_ib_dev_flush                                                |
        |                                                               |
        |                                                               |
        |                                                               |
    ipoib_mcast_dev_flush                                               |
    Move mcast list and broadcast to remove_list                        |
        |                                                               |
        |                                                               |
    Context Switch-->                                                   |
        |                                                       ipoib_ib_dev_down
        |                                                               |
        |                                                               |
        |                                                       ipoib_ib_dev_up
        |                                                               |
        |                                                               |
        |                                                       ipoib_mcast_join_task
        |                                                       allocate new broadcast
        |                                                               |
        |                                                               |
        |                                                       Attach QP to multicast group
        |                                                               |
        |                                                               |
        |                                                       <--Context Switch
    ipoib_mcast_leave
    Detach QP from multicast group
Signed-off-by: NFeras Daoud <ferasda@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>

rdma_ah_attr can now be either ib or roce allowing
core components to use one type or the other and also
to define attributes unique to a specific type. struct
ib_ah is also initialized with the type when its first
created. This ensures that calls such as modify_ah
dont modify the type of the address handle attribute.
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NDon Hiatt <don.hiatt@intel.com>
Reviewed-by: NSean Hefty <sean.hefty@intel.com>
Reviewed-by: NNiranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: NDasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Modify core and driver components to use accessor functions
introduced to access individual fields of rdma_ah_attr
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NDon Hiatt <don.hiatt@intel.com>
Reviewed-by: NSean Hefty <sean.hefty@intel.com>
Reviewed-by: NNiranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: NDasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

This patch simply renames struct ib_ah_attr to
rdma_ah_attr as these fields specify attributes that are
not necessarily specific to IB.
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NDon Hiatt <don.hiatt@intel.com>
Reviewed-by: NNiranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: NSean Hefty <sean.hefty@intel.com>
Signed-off-by: NDasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

This patch fixes a checkpatch issue related to not having
to use an 'else' if the 'if' path returns from the function.
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NDon Hiatt <don.hiatt@intel.com>
Reviewed-by: NSean Hefty <sean.hefty@intel.com>
Signed-off-by: NDasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

SA will query and cache class port info as part of
its initialization. SA will also invalidate and
refresh the cache based on specific events. Callers such
as IPoIB and CM can query the SA to get the classportinfo
information. Apart from making the caller code much simpler,
this change puts the onus on the SA to query and maintain
classportinfo much like how it maitains the address handle to the SM.
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NDon Hiatt <don.hiatt@intel.com>
Signed-off-by: NDasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Before calling ipoib_stop, rtnl_lock should be taken, then
the flow clears the IPOIB_FLAG_ADMIN_UP and IPOIB_FLAG_OPER_UP
flags, and waits for mcast completion if IPOIB_MCAST_FLAG_BUSY
is set.

On the other hand, the flow of multicast join task initializes
a mcast completion, sets the IPOIB_MCAST_FLAG_BUSY and calls
ipoib_mcast_join. If IPOIB_FLAG_OPER_UP flag is not set, this
call returns EINVAL without setting the mcast completion and
leads to a deadlock.

    ipoib_stop                          |
        |                               |
    clear_bit(IPOIB_FLAG_ADMIN_UP)      |
        |                               |
    Context Switch                      |
        |                       ipoib_mcast_join_task
        |                               |
        |                       spin_lock_irq(lock)
        |                               |
        |                       init_completion(mcast)
        |                               |
        |                       set_bit(IPOIB_MCAST_FLAG_BUSY)
        |                               |
        |                       Context Switch
        |                               |
    clear_bit(IPOIB_FLAG_OPER_UP)       |
        |                               |
    spin_lock_irqsave(lock)             |
        |                               |
    Context Switch                      |
        |                       ipoib_mcast_join
        |                       return (-EINVAL)
        |                               |
        |                       spin_unlock_irq(lock)
        |                               |
        |                       Context Switch
        |                               |
    ipoib_mcast_dev_flush               |
    wait_for_completion(mcast)          |

ipoib_stop will wait for mcast completion for ever, and will
not release the rtnl_lock. As a result panic occurs with the
following trace:

    [13441.639268] Call Trace:
    [13441.640150]  [<ffffffff8168b579>] schedule+0x29/0x70
    [13441.641038]  [<ffffffff81688fc9>] schedule_timeout+0x239/0x2d0
    [13441.641914]  [<ffffffff810bc017>] ? complete+0x47/0x50
    [13441.642765]  [<ffffffff810a690d>] ? flush_workqueue_prep_pwqs+0x16d/0x200
    [13441.643580]  [<ffffffff8168b956>] wait_for_completion+0x116/0x170
    [13441.644434]  [<ffffffff810c4ec0>] ? wake_up_state+0x20/0x20
    [13441.645293]  [<ffffffffa05af170>] ipoib_mcast_dev_flush+0x150/0x190 [ib_ipoib]
    [13441.646159]  [<ffffffffa05ac967>] ipoib_ib_dev_down+0x37/0x60 [ib_ipoib]
    [13441.647013]  [<ffffffffa05a4805>] ipoib_stop+0x75/0x150 [ib_ipoib]

Fixes: 08bc3276 ("IB/ipoib: fix for rare multicast join race condition")
Signed-off-by: NFeras Daoud <ferasda@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

IPoIB driver now uses the new set of callback functions.

If the hardware provider supports the new ipoib_options implementation,
the driver uses the callbacks in its data path flows, otherwise it uses the
driver default implementation for all data flows in its code.

The default implementation wasn't change and it is exactly as it was before
introduction of acceleration support.
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Reviewed-by: NAlex Vesker <valex@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Make ipoib_priv point to netdev_priv where the code calls netdev_priv.
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Reviewed-by: NAlex Vesker <valex@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

The function ipoib_mcast_start_thread/ipoib_ib_dev_up always return zero.
As such, in the function ipoib_open, err_stop will never be reached.
So remove this err_stop and change the return type of the function
ipoib_mcast_start_thread/ipoib_ib_dev_up to void.
Signed-off-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Add a detailed return code to dev_queue_xmit function when
calling to requeue packet via __skb_dequeue.
Signed-off-by: NFeras Daoud <ferasda@mellanox.com>
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Reviewed-by: NYuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

This patch avoids that Coverity reports the following:

    Using uninitialized value port_attr.state when calling printk

Fixes: commit 94232d9c ("IPoIB: Start multicast join process only on active ports")
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Cc: Erez Shitrit <erezsh@mellanox.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

After the commit 9207f9d4 ("net: preserve IP control block
during GSO segmentation"), the GSO CB and the IPoIB CB conflict.
That destroy the IPoIB address information cached there,
causing a severe performance regression, as better described here:

http://marc.info/?l=linux-kernel&m=146787279825501&w=2

This change moves the data cached by the IPoIB driver from the
skb control lock into the IPoIB hard header, as done before
the commit 936d7de3 ("IPoIB: Stop lying about hard_header_len
and use skb->cb to stash LL addresses").
In order to avoid GRO issue, on packet reception, the IPoIB driver
stash into the skb a dummy pseudo header, so that the received
packets have actually a hard header matching the declared length.
To avoid changing the connected mode maximum mtu, the allocated
head buffer size is increased by the pseudo header length.

After this commit, IPoIB performances are back to pre-regression
value.

v2 -> v3: rebased
v1 -> v2: avoid changing the max mtu, increasing the head buf size

Fixes: 9207f9d4 ("net: preserve IP control block during GSO segmentation")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Align locking usage when touching device address with rest
of the kernel. Lock the bottom half when doing so using
netif_addr_lock_bh.

This also solves the following case as reported by lockdep:
	CPU0                    CPU1
	----                    ----
lock(_xmit_INFINIBAND);
				local_irq_disable();
				lock(&(&mc->mca_lock)->rlock);
				lock(_xmit_INFINIBAND);
<Interrupt>
lock(&(&mc->mca_lock)->rlock);

*** DEADLOCK ***

Fixes: 492a7e67 ("IB/IPoIB: Allow setting the device address")
Signed-off-by: NMark Bloch <markb@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

In IB networks, and specifically in IPoIB/rdmacm traffic, the device
address of an IPoIB interface is used as a means to exchange information
between nodes needed for communication.

Currently an IPoIB interface will always be created with a device
address based on its node GUID without a way to change that.

This change adds the ability to set the device address of an IPoIB
interface by value. We use the set mac address ndo to do that.

The flow should be broken down to two:
1) The GID value is already in the GID table,
   in this case the interface will be able to set carrier up.

2) The GID value is not yet in the GID table,
   in this case the interface won't try to join the multicast group
   and will wait (listen on GID_CHANGE event) until the GID is inserted.

In order to track those changes, we add a new flag:
* IPOIB_FLAG_DEV_ADDR_SET.

When set, it means the dev_addr is a based on a value in the gid
table. this bit will be cleared upon a dev_addr change triggered
by the user and set after validation.

Per IB spec the port GUID can't change if the module is loaded.
port GUID is the basis for GID at index 0 which is the basis for
the default device address of a ipoib interface.

The issue is that there are devices that don't follow the spec,
they change the port GUID while HCA is powered on, so in order
not to break userspace applications. We need to check if the
user wanted to control the device address and we assume that
if he sets the device address back to be based on GID index 0,
he no longer wishs to control it.

In order to track this, we add an additional flag:
* IPOIB_FLAG_DEV_ADDR_CTRL

When setting the device address, there is no validation of the upper
twelve bytes of the device address (flags, qpn, subnet prefix) as those
bytes are not under the control of the user.
Signed-off-by: NMark Bloch <markb@mellanox.com>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Check (via an SA query) if the SM supports the new option for SendOnly
multicast joins.
If the SM supports that option it will use the new join state to create
such multicast group.
If SendOnlyFullMember is supported, we wouldn't use faked FullMember state
join for SendOnly MCG, use the correct state if supported.

This check is performed at every invocation of mcast_restart task, to be
sure that the driver stays in sync with the current state of the SM.
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

A narrow window for race condition still exist between
multicast join thread and *dev_flush workers.
A kernel crash caused by prolong erratic link state changes
was observed (most likely a faulty cabling):

[167275.656270] BUG: unable to handle kernel NULL pointer dereference at
0000000000000020
[167275.665973] IP: [<ffffffffa05f8f2e>] ipoib_mcast_join+0xae/0x1d0 [ib_ipoib]
[167275.674443] PGD 0
[167275.677373] Oops: 0000 [#1] SMP
...
[167275.977530] Call Trace:
[167275.982225]  [<ffffffffa05f92f0>] ? ipoib_mcast_free+0x200/0x200 [ib_ipoib]
[167275.992024]  [<ffffffffa05fa1b7>] ipoib_mcast_join_task+0x2a7/0x490
[ib_ipoib]
[167276.002149]  [<ffffffff8109d5fb>] process_one_work+0x17b/0x470
[167276.010754]  [<ffffffff8109e3cb>] worker_thread+0x11b/0x400
[167276.019088]  [<ffffffff8109e2b0>] ? rescuer_thread+0x400/0x400
[167276.027737]  [<ffffffff810a5aef>] kthread+0xcf/0xe0
Here was a hit spot:
ipoib_mcast_join() {
..............
      rec.qkey      = priv->broadcast->mcmember.qkey;
                                       ^^^^^^^
.....
 }
Proposed patch should prevent multicast join task to continue
if link state change is detected.
Signed-off-by: NAlex Estrin <alex.estrin@intel.com>

Changes from v4:
- as suggested by Doug Ledford, optimized spinlock usage,
i.e. ipoib_mcast_join() is called with lock held.
Changes from v3:
- sync with priv->lock before flag check.
Chages from v2:
- Move check for OPER_UP flag state to mcast_join() to
ensure no event worker is in progress.
- minor style fixes.
Changes from v1:
- No need to lock again if error detected.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

ipoib_mcast_restart_task calls ipoib_mcast_remove_list with the
parameter mcast->dev. That mcast is a temporary (used as an iterator)
variable that may be uninitialized.
There is no need to send the variable dev to the function, as each mcast
has its dev as a member in the mcast struct.

This causes the next panic:
RIP: 0010: ipoib_mcast_leave+0x6d/0xf0 [ib_ipoib]
RSP: 0018: EFLAGS: 00010246
RAX: f0201 RBX: 24e00 RCX: 00000
....
....
Stack:
Call Trace:
	ipoib_mcast_remove_list+0x3a/0x70 [ib_ipoib]
	ipoib_mcast_restart_task+0x3bb/0x520 [ib_ipoib]
	process_one_work+0x164/0x470
	worker_thread+0x11d/0x420
	...

Fixes: 5a0e81f6 ('IB/IPoIB: factor out common multicast list removal code')
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Reported-by: NDoron Tsur <doront@mellanox.com>
Reviewed-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Code cleanup to move multicast specific code that checks for
a sendonly join to ipoib_multicast.c. This allows the removal
of the export of __ipoib_mcast_find().
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Code cleanup to remove multicast specific code from ipoib_main.c

The removal of a list of multicast groups occurs in three places.
Create a new function ipoib_mcast_remove_list(). Use this new
function in ipoib_main.c too.
That in turn allows the dropping of two functions that were
exported from ipoib_multicast.c for expiration of mc groups.
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Adding an ability to query the IB cache by a netdev and get the
attributes of a GID. These parameters are necessary in order to
successfully resolve the required GID (when the netdevice is known)
and get the Ethernet L2 attributes from a GID.
Signed-off-by: NMatan Barak <matanb@mellanox.com>
Reviewed-By: NDevesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

When we leave the multicast group on expiration of a neighbor we
do not free the mcast structure. This results in a memory leak
that causes ib_dealloc_pd to fail and print a WARN_ON message
and backtrace.

Fixes: bd99b2e0 (IB/ipoib: Expire sendonly multicast joins)
Signed-off-by: NChristoph Lameter <cl@linux.com>
Tested-by: NSagi Grimberg <sagig@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

This patch split up struct ib_send_wr so that all non-trivial verbs
use their own structure which embedds struct ib_send_wr.  This dramaticly
shrinks the size of a WR for most common operations:

sizeof(struct ib_send_wr) (old):	96

sizeof(struct ib_send_wr):		48
sizeof(struct ib_rdma_wr):		64
sizeof(struct ib_atomic_wr):		96
sizeof(struct ib_ud_wr):		88
sizeof(struct ib_fast_reg_wr):		88
sizeof(struct ib_bind_mw_wr):		96
sizeof(struct ib_sig_handover_wr):	80

And with Sagi's pending MR rework the fast registration WR will also be
down to a reasonable size:

sizeof(struct ib_fastreg_wr):		64
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> [srp, srpt]
Reviewed-by: Chuck Lever <chuck.lever@oracle.com> [sunrpc]
Tested-by: NHaggai Eran <haggaie@mellanox.com>
Tested-by: NSagi Grimberg <sagig@mellanox.com>
Tested-by: NSteve Wise <swise@opengridcomputing.com>

Since IPoIB should, as much as possible, emulate how multicast
sends work on Ethernet for regular TCP/IP apps, there should be
no requirement to subscribe to a multicast group before your
sends are properly sent.  However, due to the difference in how
multicast is handled on InfiniBand, we must join the appropriate
multicast group before we can send to it.  Previously we tried
not to trigger the auto-create feature of the subnet manager when
doing this because we didn't have tracking of these sendonly
groups and the auto-creation might never get undone.  The previous
patch added timing to these sendonly joins and allows us to
leave them after a reasonable idle expiration time.  So supply
all of the information needed to auto-create group.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

On neighbor expiration, check to see if the neighbor was actually a
sendonly multicast join, and if so, leave the multicast group as we
expire the neighbor.
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

We expect send only joins to fail, it just means there are no listeners
for the group. The correct thing to do is silently drop the packet
at source.

Eg avahi will full join 224.0.0.251 which causes a send only IGMP packet
to 224.0.0.22, and then a warning level kmessage like this:

 ib0: sendonly multicast join failed for ff12:401b:ffff:0000:0000:0000:0000:0016, status -22

If there is no IP router listening to IGMP.
Signed-off-by: NJason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Even though we don't expect the group to be created by the SM we
sill need to provide all the parameters to force the SM to validate
they are correct.
Signed-off-by: NJason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

After Doug Ledford's changes there is no need in that bit, it's
semantic becomes subset of the IPOIB_FLAG_OPER_UP bit.
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Signed-off-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Update the cached broadcast record in the priv object after every new
join of this broadcast domain group.

These values are needed for the port configuration (MTU size) and to
all the new multicast (non-broadcast) join requests initial parameters.

For example, SM starts with 2K MTU for all the fabric, and after that it
restarts (or handover to new SM) with new port configuration of 4K MTU.
Without using the new values, the driver will keep its old configuration
of 2K and will not apply the new configuration of 4K.
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Signed-off-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

We needed the mcast_mutex when we had to prevent the join completion
callback from having the value it stored in mcast->mc overwritten
by a delayed return from ib_sa_join_multicast.  By storing the return
of ib_sa_join_multicast in an intermediate variable, we prevent a
delayed return from ib_sa_join_multicast overwriting the valid
contents of mcast->mc, and we no longer need a mutex to force the
join callback to run after the return of ib_sa_join_multicast.  This
allows us to do away with the mutex entirely and protect our critical
sections with a just a spinlock instead.  This is highly desirable
as there were some places where we couldn't use a mutex because the
code was not allowed to sleep, and so we were currently using a mix
of mutex and spinlock to protect what we needed to protect.  Now we
only have a spin lock and the locking complexity is greatly reduced.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Allow the ipoib layer to attempt to join all outstanding multicast
groups at once.  The ib_sa layer will serialize multiple attempts to
join the same group, but will process attempts to join different groups
in parallel.  Take advantage of that.

In order to make this happen, change the mcast_join_thread to loop
through all needed joins, sending a join request for each one that we
still need to join.  There are a few special cases we handle though:

1) Don't attempt to join anything but the broadcast group until the join
of the broadcast group has succeeded.
2) No longer restart the join task at the end of completion handling.
If we completed successfully, we are done.  The join task now needs kicked
either by mcast_send or mcast_restart_task or mcast_start_thread, but
should not need started anytime else except when scheduling a backoff
attempt to rejoin.
3) No longer use separate join/completion routines for regular and
sendonly joins, pass them all through the same routine and just do the
right thing based on the SENDONLY join flag.
4) Only try to join a SENDONLY join twice, then drop the packets and
quit trying.  We leave the mcast group in the list so that if we get a
new packet, all that we have to do is queue up the packet and restart
the join task and it will automatically try to join twice and then
either send or flush the queue again.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Commit a9c8ba58 ("IPoIB: Fix usage of uninitialized multicast
objects") added a new flag MCAST_JOIN_STARTED, but was not very strict
in how it was used.  We didn't always initialize the completion struct
before we set the flag, and we didn't always call complete on the
completion struct from all paths that complete it.  And when we did
complete it, sometimes we continued to touch the mcast entry after
the completion, opening us up to possible use after free issues.

This made it less than totally effective, and certainly made its use
confusing.  And in the flush function we would use the presence of this
flag to signal that we should wait on the completion struct, but we never
cleared this flag, ever.

In order to make things clearer and aid in resolving the rtnl deadlock
bug I've been chasing, I cleaned this up a bit.

 1) Remove the MCAST_JOIN_STARTED flag entirely
 2) Change MCAST_FLAG_BUSY so it now only means a join is in-flight
 3) Test mcast->mc directly to see if we have completed
    ib_sa_join_multicast (using IS_ERR_OR_NULL)
 4) Make sure that before setting MCAST_FLAG_BUSY we always initialize
    the mcast->done completion struct
 5) Make sure that before calling complete(&mcast->done), we always clear
    the MCAST_FLAG_BUSY bit
 6) Take the mcast_mutex before we call ib_sa_multicast_join and also
    take the mutex in our join callback.  This forces
    ib_sa_multicast_join to return and set mcast->mc before we process
    the callback.  This way, our callback can safely clear mcast->mc
    if there is an error on the join and we will do the right thing as
    a result in mcast_dev_flush.
 7) Because we need the mutex to synchronize mcast->mc, we can no
    longer call mcast_sendonly_join directly from mcast_send and
    instead must add sendonly join processing to the mcast_join_task
 8) Make MCAST_RUN mean that we have a working mcast subsystem, not that
    we have a running task.  We know when we need to reschedule our
    join task thread and don't need a flag to tell us.
 9) Add a helper for rescheduling the join task thread

A number of different races are resolved with these changes.  These
races existed with the old MCAST_FLAG_BUSY usage, the
MCAST_JOIN_STARTED flag was an attempt to address them, and while it
helped, a determined effort could still trip things up.

One race looks something like this:

Thread 1                             Thread 2
ib_sa_join_multicast (as part of running restart mcast task)
  alloc member
  call callback
                                     ifconfig ib0 down
				     wait_for_completion
    callback call completes
                                     wait_for_completion in
				     mcast_dev_flush completes
				       mcast->mc is PTR_ERR_OR_NULL
				       so we skip ib_sa_leave_multicast
    return from callback
  return from ib_sa_join_multicast
set mcast->mc = return from ib_sa_multicast

We now have a permanently unbalanced join/leave issue that trips up the
refcounting in core/multicast.c

Another like this:

Thread 1                   Thread 2         Thread 3
ib_sa_multicast_join
                                            ifconfig ib0 down
					    priv->broadcast = NULL
                           join_complete
			                    wait_for_completion
			   mcast->mc is not yet set, so don't clear
return from ib_sa_join_multicast and set mcast->mc
			   complete
			   return -EAGAIN (making mcast->mc invalid)
			   		    call ib_sa_multicast_leave
					    on invalid mcast->mc, hang
					    forever

By holding the mutex around ib_sa_multicast_join and taking the mutex
early in the callback, we force mcast->mc to be valid at the time we
run the callback.  This allows us to clear mcast->mc if there is an
error and the join is going to fail.  We do this before we complete
the mcast.  In this way, mcast_dev_flush always sees consistent state
in regards to mcast->mc membership at the time that the
wait_for_completion() returns.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

Various places in the IPoIB code had a deadlock related to flushing
the ipoib workqueue.  Now that we have per device workqueues and a
specific flush workqueue, there is no longer a deadlock issue with
flushing the device specific workqueues and we can do so unilaterally.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

During my recent work on the rtnl lock deadlock in the IPoIB driver, I
saw that even once I fixed the apparent races for a single device, as
soon as that device had any children, new races popped up.  It turns
out that this is because no matter how well we protect against races
on a single device, the fact that all devices use the same workqueue,
and flush_workqueue() flushes *everything* from that workqueue means
that we would also have to prevent all races between different devices
(for instance, ipoib_mcast_restart_task on interface ib0 can race with
ipoib_mcast_flush_dev on interface ib0.8002, resulting in a deadlock on
the rtnl_lock).

There are several possible solutions to this problem:

Make carrier_on_task and mcast_restart_task try to take the rtnl for
some set period of time and if they fail, then bail.  This runs the
real risk of dropping work on the floor, which can end up being its
own separate kind of deadlock.

Set some global flag in the driver that says some device is in the
middle of going down, letting all tasks know to bail.  Again, this can
drop work on the floor.

Or the method this patch attempts to use, which is when we bring an
interface up, create a workqueue specifically for that interface, so
that when we take it back down, we are flushing only those tasks
associated with our interface.  In addition, keep the global
workqueue, but now limit it to only flush tasks.  In this way, the
flush tasks can always flush the device specific work queues without
having deadlock issues.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

We blindly assume that we can just take the rtnl lock and that will
prevent races with downing this interface.  Unfortunately, that's not
the case.  In ipoib_mcast_stop_thread() we will call flush_workqueue()
in an attempt to clear out all remaining instances of ipoib_join_task.
But, since this task is put on the same workqueue as the join task,
the flush_workqueue waits on this thread too.  But this thread is
deadlocked on the rtnl lock.  The better thing here is to use trylock
and loop on that until we either get the lock or we see that
FLAG_OPER_UP has been cleared, in which case we don't need to do
anything anyway and we just return.

While investigating which flag should be used, FLAG_ADMIN_UP or
FLAG_OPER_UP, it was determined that FLAG_OPER_UP was the more
appropriate flag to use.  However, there was a mix of these two flags in
use in the existing code.  So while we check for that flag here as part
of this race fix, also cleanup the two places that had used the less
appropriate flag for their tests.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

The ipoib_mcast_flush_dev routine is called with the rtnl_lock held and
needs to keep it held.  It also needs to call flush_workqueue() to flush
out any outstanding work.  In the past, we've had to try and make sure
that we didn't flush out any outstanding join completions because they
also wanted to grab rtnl_lock() and that would deadlock.  It turns out
that the only thing in the join completion handler that needs this lock
can be safely moved to our carrier_on_task, thereby reducing the
potential for the join completion code and the flush code to deadlock
against each other.
Signed-off-by: NDoug Ledford <dledford@redhat.com>

This reverts commit afe1de66.

The series of IPoIB bug fixes that went into 3.19-rc1 introduce
regressions, and after trying to sort things out, we decided to revert
to 3.18's IPoIB driver and get things right for 3.20.
Signed-off-by: NRoland Dreier <roland@purestorage.com>

This reverts commit 67d7209e.

The series of IPoIB bug fixes that went into 3.19-rc1 introduce
regressions, and after trying to sort things out, we decided to revert
to 3.18's IPoIB driver and get things right for 3.20.
Signed-off-by: NRoland Dreier <roland@purestorage.com>