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authorPradeep Satyanarayana <pradeeps@linux.vnet.ibm.com>2008-01-25 14:15:24 -0800
committerRoland Dreier <rolandd@cisco.com>2008-01-25 14:15:24 -0800
commit68e995a295720439ad2bf8677114cdf9d262d905 (patch)
tree24de129501f4fb576f1fc9eef90900a342707278 /drivers/scsi/NCR_Q720.h
parentefcd99717f76c6d19dd81203c60fe198480de522 (diff)
IPoIB/cm: Add connected mode support for devices without SRQs
Some IB adapters (notably IBM's eHCA) do not implement SRQs (shared receive queues). The current IPoIB connected mode support only works on devices that support SRQs. Fix this by adding support for using the receive queue of each connected mode receive QP. The disadvantage of this compared to using an SRQ is that it means a full queue of receives must be posted for each remote connected mode peer, which means that total memory usage is potentially much higher than when using SRQs. To manage this, add a new module parameter "max_nonsrq_conn_qp" that limits the number of connections allowed per interface. The rest of the changes are fairly straightforward: we use a table of struct ipoib_cm_rx to hold all the active connections, and put the table index of the connection in the high bits of receive WR IDs. This is needed because we cannot rely on the struct ib_wc.qp field for non-SRQ receive completions. Most of the rest of the changes just test whether or not an SRQ is available, and post receives or find received packets in the right place depending on the answer. Cleaning up dead connections actually becomes simpler, because we do not have to do the "last WQE reached" dance that is required to destroy QPs attached to an SRQ. We just move the QP to the error state and wait for all pending receives to be flushed. Signed-off-by: Pradeep Satyanarayana <pradeeps@linux.vnet.ibm.com> [ Completely rewritten and split up, based on Pradeep's work. Several bugs fixed and no doubt several bugs introduced. - Roland ] Signed-off-by: Roland Dreier <rolandd@cisco.com>
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