scsi: target: Check enforce_pr_isids during registration

Move the check for enforce_pr_isids to the registration code where we can
fail at the time an initiator tries to register a path without an isid. In
its current place in __core_scsi3_locate_pr_reg, it is too late because it
can be registered and be reported in PR in commands and it is stuck in this
state because we cannot unregister it.

[mkp: applied by hand]

Link: https://lore.kernel.org/r/1593654203-12442-2-git-send-email-michael.christie@oracle.com
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/target_core_pr.c

@@ -1176,15 +1176,6 @@ static struct t10_pr_registration *__core_scsi3_locate_pr_reg(
 		 * ISID, then we have found a match.
 		 */
 		if (!pr_reg->isid_present_at_reg) {
-			/*
-			 * Determine if this SCSI device server requires that
-			 * SCSI Intiatior TransportID w/ ISIDs is enforced
-			 * for fabric modules (iSCSI) requiring them.
-			 */
-			if (tpg->se_tpg_tfo->sess_get_initiator_sid != NULL) {
-				if (dev->dev_attrib.enforce_pr_isids)
-					continue;
-			}
 			atomic_inc_mb(&pr_reg->pr_res_holders);
 			spin_unlock(&pr_tmpl->registration_lock);
 			return pr_reg;
@@ -1591,10 +1582,25 @@ core_scsi3_decode_spec_i_port(
 				continue;
 			dest_rtpi = tmp_lun->lun_rtpi;
 
+			iport_ptr = NULL;
 			i_str = target_parse_pr_out_transport_id(tmp_tpg,
 					ptr, &tid_len, &iport_ptr);
 			if (!i_str)
 				continue;
+			/*
+			 * Determine if this SCSI device server requires that
+			 * SCSI Intiatior TransportID w/ ISIDs is enforced
+			 * for fabric modules (iSCSI) requiring them.
+			 */
+			if (tpg->se_tpg_tfo->sess_get_initiator_sid &&
+			    dev->dev_attrib.enforce_pr_isids &&
+			    !iport_ptr) {
+				pr_warn("SPC-PR: enforce_pr_isids is set but a isid has not been sent in the SPEC_I_PT data for %s.",
+					i_str);
+				ret = TCM_INVALID_PARAMETER_LIST;
+				spin_unlock(&dev->se_port_lock);
+				goto out_unmap;
+			}
 
 			atomic_inc_mb(&tmp_tpg->tpg_pr_ref_count);
 			spin_unlock(&dev->se_port_lock);