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[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>
This commit is contained in:
mdr@sgi.com 2006-05-01 13:07:04 -05:00 committed by James Bottomley
parent 0b18ac42aa
commit 6dd727da92
1 changed files with 7 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/message/fusion/mptfc.c
View File

@ -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;