[SCSI] mptfc: race between mptfc_register_dev and mptfc_target_alloc

[SCSI] mptfc: race between mptfc_register_dev and mptfc_target_alloc

A race condition exists in mptfc between the thread registering a device
with the fc transport and the scan work generated by the transport.
This race existed prior to the application of the mptfc bug fix patch.

mptfc_register_dev() calls fc_remote_port_add() with the FC_RPORT_ROLE_TARGET
bit set in the rport ids passed to the function.  Having this bit set causes
fc_remote_port_add() to schedule a scan of the device.

This scan can execute before mptfc_register_dev() can fill in the dd_data
in the rport structure.  When this happens, mptfc_target_alloc() will fail
because dd_data is null.

Attached is a patch which fixes the problem.  The patch changes the rport ids
passed to fc_remote_port_add() to not have the TARGET bit set.  This prevents
the scan from being scheduled.  After mptfc_register_dev() fills in the rport
dd_data field, fc_remote_port_rolechg() is called, changing the role of the
rport to TARGET.  Thus, the scan is scheduled after dd_data is filled
in which prevents the failure in mptfc_target_alloc().

Signed-off-by: Michael Reed <mdr@sgi.com>
Signed-off-by: Eric Moore <Eric.Moore@lsil.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>