After reporting a new connection request to user space, the rdma_ucm
will discard subsequent events until the user has associated a user
space idenfier with the kernel cm_id.  This is needed to avoid
reporting a reject/disconnect event to the user for a request that
they may not have processed.

The user space identifier is set once the user tries to accept the
connection request.  However, the following race exists in ucma_accept():

	ctx->uid = cmd.uid;
	<events may be reported now>
	ret = rdma_accept(ctx->cm_id, ...);

Once ctx->uid has been set, new events may be reported to the user.
While the above mentioned race is avoided, there is an issue that the
user _may_ receive a reject/disconnect event if rdma_accept() fails,
depending on when the event is processed.  To simplify the use of
rdma_accept(), discard all events unless rdma_accept() succeeds.

This problem was discovered based on questions from Roland Dreier
<roland@purestorage.com>.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

We have just been investigating kernel panics related to
cq->ibcq.event_handler() completion calls.  The problem is that
ib_destroy_qp() fails with -EBUSY.

Further investigation revealed qp->usecnt is not initialized.  This
counter was introduced in linux-3.2 by commit 0e0ec7e0638e
("RDMA/core: Export ib_open_qp() to share XRC TGT QPs") but it only
gets initialized for IB_QPT_XRC_TGT, but it is checked in
ib_destroy_qp() for any QP type.

Fix this by initializing qp->usecnt for every QP we create.

Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Signed-off-by: Sven Breuner <sven.breuner@itwm.fraunhofer.de>

[ Initialize qp->usecnt in uverbs too.  - Sean ]

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

infiniband changes for 3.3 merge window

* tag 'infiniband-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  rdma/core: Fix sparse warnings
  RDMA/cma: Fix endianness bugs
  RDMA/nes: Fix terminate during AE
  RDMA/nes: Make unnecessarily global nes_set_pau() static
  RDMA/nes: Change MDIO bus clock to 2.5MHz
  IB/cm: Fix layout of APR message
  IB/mlx4: Fix SL to 802.1Q priority-bits mapping for IBoE
  IB/qib: Default some module parameters optimally
  IB/qib: Optimize locking for get_txreq()
  IB/qib: Fix a possible data corruption when receiving packets
  IB/qib: Eliminate 64-bit jiffies use
  IB/qib: Fix style issues
  IB/uverbs: Protect QP multicast list

* 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (165 commits)
  reiserfs: Properly display mount options in /proc/mounts
  vfs: prevent remount read-only if pending removes
  vfs: count unlinked inodes
  vfs: protect remounting superblock read-only
  vfs: keep list of mounts for each superblock
  vfs: switch ->show_options() to struct dentry *
  vfs: switch ->show_path() to struct dentry *
  vfs: switch ->show_devname() to struct dentry *
  vfs: switch ->show_stats to struct dentry *
  switch security_path_chmod() to struct path *
  vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb
  vfs: trim includes a bit
  switch mnt_namespace ->root to struct mount
  vfs: take /proc/*/mounts and friends to fs/proc_namespace.c
  vfs: opencode mntget() mnt_set_mountpoint()
  vfs: spread struct mount - remaining argument of next_mnt()
  vfs: move fsnotify junk to struct mount
  vfs: move mnt_devname
  vfs: move mnt_list to struct mount
  vfs: switch pnode.h macros to struct mount *
  ...

Clean up sparse warnings in the rdma core layer.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

Fix endianness bugs reported by sparse in the RDMA core stack.  Note
that these are real bugs, but don't affect any existing code to the
best of my knowledge.  The mlid issue would only affect kernel users
of rdma_join_multicast which have the rdma_cm attach/detach its QP.
There are no current in tree users that do this. (rdma_join_multicast
may be used called by user space applications, which does not have
this issue.)  And the pkey setting is simply returned as
informational.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

Add a missing 16-bit reserved field between ap_status and info fields.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Acked-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

Userspace verbs multicast attach/detach operations on a QP are done
while holding the rwsem of the QP for reading.  That's not sufficient
since a reader lock allows more than one reader to acquire the
lock.  However, multicast attach/detach does list manipulation that
can corrupt the list if multiple threads run in parallel.

Fix this by acquiring the rwsem as a writer to serialize attach/detach
operations.  Add idr_write_qp() and put_qp_write() to encapsulate
this.

This fixes oops seen when running applications that perform multicast
joins/leaves.

Reported by: Mike Dubman <miked@mellanox.com>
Signed-off-by: Eli Cohen <eli@mellanox.com>
Cc: <stable@kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>