[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>
diff --git a/drivers/message/fusion/mptfc.c b/drivers/message/fusion/mptfc.c
index e1fb5a1..8564877 100644
--- a/drivers/message/fusion/mptfc.c
+++ b/drivers/message/fusion/mptfc.c
@@ -341,9 +341,6 @@
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 @@
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 @@
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;