The vzalloc()'ed field physshadow is leaked on module unload.

This patch adds vfree after the sibling page shadow is freed.
Reported-by: NDean Luick <dean.luick@intel.com>
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

The Dell blade chassis got an updated backplane which requires new
transmitter tuning settings.
Signed-off-by: NMitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

This adds a seq_file iterator for reporting the QP hash table when the
qp_stats file is read.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

This patch adds a debugfs stats interface for per kernel contexts
packet counts.

The code uses the opcode stats count and eliminates the counter in the
context.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

This fix changes the opcode relative counters for receive to per
context.

Profiling has shown that when mulitple contexts are being used there
is a lot of cache activity associated with these counters.

The code formerly kept these counters per port, but only provided the
interface to read per HCA.  This patch converts the read of counters
to per HCA and adds the debugfs hooks to be able to read the file as a
sequence of opcodes.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

The current workqueue implemention has the following performance
deficiencies on QDR HCAs:

- The CQ call backs tend to run on the CPUs processing the
  receive queues
- The single thread queue isn't optimal for multiple HCAs

This patch adds a dedicated per HCA bound thread to process CQ callbacks.
Reviewed-by: NRamkrishna Vepa <ramkrishna.vepa@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

The driver currently selects a HCA based on the algorithm that PSM
chooses, contexts within a HCA or across. The HCA can also be chosen
by the user. Either way, this patch assigns a CPU on the NUMA node
local to the selected HCA. This patch also tries to select the HCA
closest to the NUMA node of the CPU assigned via taskset to PSM
process. If this HCA is unusable then another unit is selected based
on the algorithm that is currently enforced or selected by PSM - round
robin context selection 'within' or 'across' HCA's.

Fixed a bug wherein contexts are setup on the NUMA node on which the
processes are opened (setup_ctxt()) and not on the NUMA node that the
driver recommends the CPU on.
Reviewed-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NVinit Agnihotri <vinit.abhay.agnihotri@intel.com>
Signed-off-by: NRamkrishna Vepa <ramkrishna.vepa@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

This patch adds context relative numa affinity conditioned on the
module parameter numa_aware. The qib_ctxtdata has an additional
node_id member and qib_create_ctxtdata() has an addition node_id
parameter.

The allocations within the hdr queue and eager queue setup routines
now take this additional member and adjust allocations as necesary.
PSM will pass the either current numa node or the node closest to the
HCA depending on numa_aware. Verbs will always use the node closest to
the HCA.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NRamkrishna Vepa <ramkrishna.vepa@intel.com>
Signed-off-by: NVinit Agnihotri <vinit.abhay.agnihotri@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

External PSM repositories have advanced the minor number for a variety
of reasons. The driver needs to increase to avoid warnings.
Signed-off-by: NVinit Agnihotri <vinit.abhay.agnihotri@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Follow Documentation/RCU/rcuref.txt guidance in removing
atomic_inc_not_zero() from QP RCU implementation.

This patch also removes an unneeded synchronize_rcu() in the add path.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

This patch adds DCA cache warming for systems that support DCA.

The code uses cpu affinity notification to react to an affinity change
from a user mode program like irqbalance and (re-)program the chip
accordingly. This notification avoids reading the current cpu on every
interrupt.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>

[ Add Kconfig dependency on SMP && GENERIC_HARDIRQS to avoid failure to
  build due to undefined struct irq_affinity_notify.  - Roland ]
Signed-off-by: NRoland Dreier <roland@purestorage.com>

The following backtrace is reported with CONFIG_PROVE_RCU:

    drivers/infiniband/hw/qib/qib_keys.c:64 suspicious rcu_dereference_check() usage!
    other info that might help us debug this:
    rcu_scheduler_active = 1, debug_locks = 1
    4 locks held by kworker/0:1/56:
    #0:  (events){.+.+.+}, at: [<ffffffff8107a4f5>] process_one_work+0x165/0x4a0
    #1:  ((&wfc.work)){+.+.+.}, at: [<ffffffff8107a4f5>] process_one_work+0x165/0x4a0
    #2:  (device_mutex){+.+.+.}, at: [<ffffffffa0148dd8>] ib_register_device+0x38/0x220 [ib_core]
    #3:  (&(&dev->lk_table.lock)->rlock){......}, at: [<ffffffffa017e81c>] qib_alloc_lkey+0x3c/0x1b0 [ib_qib]

    stack backtrace:
    Pid: 56, comm: kworker/0:1 Not tainted 3.10.0-rc1+ #6
    Call Trace:
    [<ffffffff810c0b85>] lockdep_rcu_suspicious+0xe5/0x130
    [<ffffffffa017e8e1>] qib_alloc_lkey+0x101/0x1b0 [ib_qib]
    [<ffffffffa0184886>] qib_get_dma_mr+0xa6/0xd0 [ib_qib]
    [<ffffffffa01461aa>] ib_get_dma_mr+0x1a/0x50 [ib_core]
    [<ffffffffa01678dc>] ib_mad_port_open+0x12c/0x390 [ib_mad]
    [<ffffffff810c2c55>] ?  trace_hardirqs_on_caller+0x105/0x190
    [<ffffffffa0167b92>] ib_mad_init_device+0x52/0x110 [ib_mad]
    [<ffffffffa01917c0>] ?  sl2vl_attr_show+0x30/0x30 [ib_qib]
    [<ffffffffa0148f49>] ib_register_device+0x1a9/0x220 [ib_core]
    [<ffffffffa01b1685>] qib_register_ib_device+0x735/0xa40 [ib_qib]
    [<ffffffff8106ba98>] ? mod_timer+0x118/0x220
    [<ffffffffa017d425>] qib_init_one+0x1e5/0x400 [ib_qib]
    [<ffffffff812ce86e>] local_pci_probe+0x4e/0x90
    [<ffffffff81078118>] work_for_cpu_fn+0x18/0x30
    [<ffffffff8107a566>] process_one_work+0x1d6/0x4a0
    [<ffffffff8107a4f5>] ?  process_one_work+0x165/0x4a0
    [<ffffffff8107c9c9>] worker_thread+0x119/0x370
    [<ffffffff8107c8b0>] ?  manage_workers+0x180/0x180
    [<ffffffff8108294e>] kthread+0xee/0x100
    [<ffffffff81082860>] ?  __init_kthread_worker+0x70/0x70
    [<ffffffff815c04ac>] ret_from_fork+0x7c/0xb0
    [<ffffffff81082860>] ?  __init_kthread_worker+0x70/0x70

Per Documentation/RCU/lockdep-splat.txt, the code now uses rcu_access_pointer()
vs. rcu_dereference().
Reported-by: NJay Fenlason <fenlason@redhat.com>
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Faster kernel compiles by way of fewer unnecessary includes.

[akpm@linux-foundation.org: fix fallout]
[akpm@linux-foundation.org: fix build]
Signed-off-by: NKent Overstreet <koverstreet@google.com>
Cc: Zach Brown <zab@redhat.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Reviewed-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

qib_verbs_register_sysfs() never cleans up from a failure.
Additionally, the caller of qib_verbs_register_sysfs() doesn't
return the correct "ret" value.

This patch resolves both of those issues.
Reported-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Commit e2eed58b ("IB/qib: change QLogic to Intel") moved a firmware
file potentially breaking the ABI.

This patch reverts that aspect of the fix as well as reverting the
firmware name as used in qib.
Reported-by: NDavid Woodhouse <dwmw2@infradead.org>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These changes modify the qib driver as part of acquiring
the InfiniBand assets of QLogic.
Reviewed-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NVinit Agnihotri <vinit.abhay.agnihotri@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Modify the request_module to prefix the file system type with "fs-"
and add aliases to all of the filesystems that can be built as modules
to match.

A common practice is to build all of the kernel code and leave code
that is not commonly needed as modules, with the result that many
users are exposed to any bug anywhere in the kernel.

Looking for filesystems with a fs- prefix limits the pool of possible
modules that can be loaded by mount to just filesystems trivially
making things safer with no real cost.

Using aliases means user space can control the policy of which
filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf
with blacklist and alias directives.  Allowing simple, safe,
well understood work-arounds to known problematic software.

This also addresses a rare but unfortunate problem where the filesystem
name is not the same as it's module name and module auto-loading
would not work.  While writing this patch I saw a handful of such
cases.  The most significant being autofs that lives in the module
autofs4.

This is relevant to user namespaces because we can reach the request
module in get_fs_type() without having any special permissions, and
people get uncomfortable when a user specified string (in this case
the filesystem type) goes all of the way to request_module.

After having looked at this issue I don't think there is any
particular reason to perform any filtering or permission checks beyond
making it clear in the module request that we want a filesystem
module.  The common pattern in the kernel is to call request_module()
without regards to the users permissions.  In general all a filesystem
module does once loaded is call register_filesystem() and go to sleep.
Which means there is not much attack surface exposed by loading a
filesytem module unless the filesystem is mounted.  In a user
namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT,
which most filesystems do not set today.
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Acked-by: NKees Cook <keescook@chromium.org>
Reported-by: NKees Cook <keescook@google.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Convert to the much saner new idr interface.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Mike Marciniszyn <infinipath@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

remove_qp() can execute concurrently with a qib_lookup_qpn() on
another CPU, which in of itself, is ok, given the RCU locking.

The issue is that remove_qp() NULLs out the qp->next field so that a
qib_lookup_qpn() might fail to find a qp if it occurs after the one
that is being deleted.  This is a momentary issue and subsequent
qib_lookup_qpn() calls would find the qp's since the search restarts
from the bucket head.  At scale, the issue might causes dropped
packets and unnecessary retransmissions.

The fix just deletes the qp->next NULL assignment to prevent the
remove_qp() from hiding qp's from qib_lookup_qpn().
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Commit 1fb9fed6 ("IB/qib: Fix QP RCU sparse warning") broke QP
hash list deletion in qp_remove() badly.

This patch restores the former for loop behavior, while still fixing
the sparse warnings.

Cc: <stable@vger.kernel.org>
Reviewed-by: NGary Leshner <gary.s.leshner@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

CONFIG_HOTPLUG is going away as an option.  As a result, the __dev*
markings need to be removed.

This change removes the use of __devinit, __devexit_p, __devinitdata,
and __devexit from these drivers.

Based on patches originally written by Bill Pemberton, but redone by me
in order to handle some of the coding style issues better, by hand.

Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Tom Tucker <tom@opengridcomputing.com>
Cc: Steve Wise <swise@opengridcomputing.com>
Cc: Roland Dreier <roland@kernel.org>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Cc: Christoph Raisch <raisch@de.ibm.com>
Cc: Mike Marciniszyn <infinipath@intel.com>
Cc: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A long time ago, in v2.4, VM_RESERVED kept swapout process off VMA,
currently it lost original meaning but still has some effects:

 | effect                 | alternative flags
-+------------------------+---------------------------------------------
1| account as reserved_vm | VM_IO
2| skip in core dump      | VM_IO, VM_DONTDUMP
3| do not merge or expand | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
4| do not mlock           | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP

This patch removes reserved_vm counter from mm_struct.  Seems like nobody
cares about it, it does not exported into userspace directly, it only
reduces total_vm showed in proc.

Thus VM_RESERVED can be replaced with VM_IO or pair VM_DONTEXPAND | VM_DONTDUMP.

remap_pfn_range() and io_remap_pfn_range() set VM_IO|VM_DONTEXPAND|VM_DONTDUMP.
remap_vmalloc_range() set VM_DONTEXPAND | VM_DONTDUMP.

[akpm@linux-foundation.org: drivers/vfio/pci/vfio_pci.c fixup]
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Venkatesh Pallipadi <venki@google.com>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 8aac4cc3 ("IB/qib: RCU locking for MR validation") introduced
a bug that broke user post sends.  The proper validation of the MR
was lost in the patch.

This patch corrects that validation.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Reviewed-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Acked-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

Commit 3236b2d4 ("IB/qib: MADs with misset M_Keys should return
failure") introduced a return code assignment that unfortunately
introduced an unconditional exit for the routine due to missing braces.

This patch adds the braces to correct the original patch.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Covers the rest of the uses of pci error handler.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Use PCI Express Capability access functions to simplify qib driver.
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NMike Marciniszyn <mike.marciniszyn@intel.com>

Convert a 0 error return code to a negative one, as returned elsewhere
in the function.

A simplified version of the semantic match that finds this problem is
as follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
identifier ret;
expression e,e1,e2,e3,e4,x;
@@

(
if (\(ret != 0\|ret < 0\) || ...) { ... return ...; }
|
ret = 0
)
... when != ret = e1
*x = \(kmalloc\|kzalloc\|kcalloc\|devm_kzalloc\|ioremap\|ioremap_nocache\|devm_ioremap\|devm_ioremap_nocache\)(...);
... when != x = e2
    when != ret = e3
*if (x == NULL || ...)
{
  ... when != ret = e4
*  return ret;
}
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Acked-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Correct spelling typos in comments in drivers/infiniband.
Signed-off-by: NMasanari Iida <standby24x7@gmail.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Commit 36a8f01c ("IB/qib: Add congestion control agent
implementation") tries to store the value 1984 in a u8, which leads to
truncation.  Fix this by making the member big enough.

This bug was detected by a smatch warning.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NRamkrishna Vepa <ramkrishna.vepa@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Elminate some simple_strto* usage.

checkpatch also noted pr_ conversations, which have been done as
recommended.  The pr_fmt() define is used to shorten line length.

Other multi-line string warnings are also elmininated.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Add a congestion control agent in the driver that handles gets and
sets from the congestion control manager in the fabric for the
Performance Scale Messaging (PSM) library.
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Profiling has shown that sdma_lock is proving a bottleneck for
performance. The situations include:
 - RDMA reads when krcvqs > 1
 - post sends from multiple threads

For RDMA read the current global qib_wq mechanism runs on all CPUs
and contends for the sdma_lock when multiple RMDA read requests are
fielded on differenct CPUs. For post sends, the direct call to
qib_do_send() from multiple threads causes the contention.

Since the sdma mechanism is per port, this fix converts the existing
workqueue to a per port single thread workqueue to reduce the lock
contention in the RDMA read case, and for any other case where the QP
is scheduled via the workqueue mechanism from more than 1 CPU.

For the post send case, This patch modifies the post send code to test
for a non empty sdma engine.  If the sdma is not idle the (now single
thread) workqueue will be used to trigger the send engine instead of
the direct call to qib_do_send().
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

There is a cut-and-paste typo in the function qib_pci_slot_reset()
where it prints that the "link_reset" function is called rather than
the "slot_reset" function.  This makes the message misleading.
Signed-off-by: NBetty Dall <betty.dall@hp.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Commit af061a64 ("IB/qib: Use RCU for qpn lookup") introduced sparse
warnings.

This patch corrects those issues.
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Commit 8aac4cc3 ("IB/qib: RCU locking for MR validation") introduced
new sparse warnings in qib_keys.c.
Acked-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

Profiling indicates that MR validation locking is expensive.  The MR
table is largely read-only and is a suitable candidate for RCU locking.

The patch uses RCU locking during validation to eliminate one
lock/unlock during that validation.
Reviewed-by: NMike Heinz <michael.william.heinz@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

A timing issue can occur where qib_mr_dereg can return -EBUSY if the
MR use count is not zero.

This can occur if the MR is de-registered while RDMA read response
packets are being progressed from the SDMA ring.  The suspicion is
that the peer sent an RDMA read request, which has already been copied
across to the peer.  The peer sees the completion of his request and
then communicates to the responder that the MR is not needed any
longer.  The responder tries to de-register the MR, catching some
responses remaining in the SDMA ring holding the MR use count.

The code now uses a get/put paradigm to track MR use counts and
coordinates with the MR de-registration process using a completion
when the count has reached zero.  A timeout on the delay is in place
to catch other EBUSY issues.

The reference count protocol is as follows:
- The return to the user counts as 1
- A reference from the lk_table or the qib_ibdev counts as 1.
- Transient I/O operations increase/decrease as necessary

A lot of code duplication has been folded into the new routines
init_qib_mregion() and deinit_qib_mregion().  Additionally, explicit
initialization of fields to zero is now handled by kzalloc().

Also, duplicated code 'while.*num_sge' that decrements reference
counts have been consolidated in qib_put_ss().
Reviewed-by: NRamkrishna Vepa <ramkrishna.vepa@intel.com>
Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>