This is based on user feedback from Doug Ledford at RedHat:
Events that occur on an rdma_cm_id are reported to userspace through an
event channel. Connection request events are reported on the event
channel associated with the listen. When the connection is accepted, a
new rdma_cm_id is created and automatically uses the listen event
channel. This is suboptimal where the user only wants listen events on
that channel.
Additionally, it may be desirable to have events related to connection
establishment use a different event channel than those related to
already established connections.
Allow the user to migrate an rdma_cm_id between event channels. All
pending events associated with the rdma_cm_id are moved to the new event
channel.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Export the ability to set the type of service to user space. Model
the interface after setsockopt.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Change the returned error code to ENOMEM if the connection event
backlog is full. This prevents the ib_cm from issuing a reject
on the connection, which can allow retries to succeed.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Extend rdma_cm to support multicast communication. Multicast support
is added to the existing RDMA_PS_UDP port space, as well as a new
RDMA_PS_IPOIB port space. The latter port space allows joining the
multicast groups used by IPoIB, which enables offloading IPoIB traffic
to a separate QP. The port space determines the signature used in the
MGID when joining the group. The newly added RDMA_PS_IPOIB also
allows for unicast operations, similar to RDMA_PS_UDP.
Supporting the RDMA_PS_IPOIB requires changing how UD QPs are initialized,
since we can no longer assume that the qkey is constant. This requires
saving the Q_Key to use when attaching to a device, so that it is
available when creating the QP. The Q_Key information is exported to
the user through the existing rdma_init_qp_attr() interface.
Multicast support is also exported to userspace through the rdma_ucm.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Many struct file_operations in the kernel can be "const". Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data. In addition it'll catch accidental writes at compile time to
these shared resources.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's a problem with how rdma cm events are reported to userspace
that can lead to application crashes.
When a new connection request arrives, a context for the connection is
allocated in the kernel. The connection event is then reported to
userspace. The userspace library retrieves the event and allocates
its own context for the connection. The userspace context is
associated with the kernel's context when accepting. This allows the
kernel to give userspace context with other events.
A problem occurs if a second event for the same connection occurs
before the user has had a chance to call accept. The userspace
context has not yet been set, which causes the librdmacm to crash.
(This has been seen when the app takes too long to call accept,
resulting in the remote side timing out and rejecting the connection)
Fix this by ignoring events for new connections until userspace has
set their context. This can only happen if an error occurs on a new
connection before the user accepts it. This is okay, since the accept
will just fail later.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
We discard new connection requests while the listen backlog is full,
but leak a struct ucma_event in the process. Free the structure in
this case.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Export the rdma cm interfaces to userspace via a misc device.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Sean Hefty
Arjan van de Ven