[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>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/message/fusion/mptfc.c b/drivers/message/fusion/mptfc.c
index e1fb5a166366..856487741ef4 100644
--- a/drivers/message/fusion/mptfc.c
+++ b/drivers/message/fusion/mptfc.c
@@ -341,9 +341,6 @@ mptfc_generate_rport_ids(FCDevicePage0_t *pg0, struct fc_rport_identifiers *rid)
         rid->port_name = ((u64)pg0->WWPN.High) << 32 | (u64)pg0->WWPN.Low;
         rid->port_id =   pg0->PortIdentifier;
         rid->roles = FC_RPORT_ROLE_UNKNOWN;
-        rid->roles |= FC_RPORT_ROLE_FCP_TARGET;
-        if (pg0->Protocol & MPI_FC_DEVICE_PAGE0_PROT_FCP_INITIATOR)
-                rid->roles |= FC_RPORT_ROLE_FCP_INITIATOR;
 
         return 0;
 }
@@ -357,10 +354,15 @@ mptfc_register_dev(MPT_ADAPTER *ioc, int channel, FCDevicePage0_t *pg0)
         int                     new_ri = 1;
         u64                     pn, nn;
         VirtTarget              *vtarget;
+        u32                     roles = FC_RPORT_ROLE_UNKNOWN;
 
         if (mptfc_generate_rport_ids(pg0, &rport_ids) < 0)
                 return;
 
+        roles |= FC_RPORT_ROLE_FCP_TARGET;
+        if (pg0->Protocol & MPI_FC_DEVICE_PAGE0_PROT_FCP_INITIATOR)
+                roles |= FC_RPORT_ROLE_FCP_INITIATOR;
+
         /* scan list looking for a match */
         list_for_each_entry(ri, &ioc->fc_rports, list) {
                 pn = (u64)ri->pg0.WWPN.High << 32 | (u64)ri->pg0.WWPN.Low;
@@ -400,8 +402,9 @@ mptfc_register_dev(MPT_ADAPTER *ioc, int channel, FCDevicePage0_t *pg0)
                                         vtarget->bus_id = pg0->CurrentBus;
                                 }
                         }
-                        /* once dd_data is filled in, commands will issue to hardware */
                         *((struct mptfc_rport_info **)rport->dd_data) = ri;
+                        /* scan will be scheduled once rport becomes a target */
+                        fc_remote_port_rolechg(rport,roles);
 
                         pn = (u64)ri->pg0.WWPN.High << 32 | (u64)ri->pg0.WWPN.Low;
                         nn = (u64)ri->pg0.WWNN.High << 32 | (u64)ri->pg0.WWNN.Low;