Merge git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending

Pull SCSI target fixes from Nicholas Bellinger:
 "This contains a v4.2-rc specific RCU module unload regression bug-fix,
  a long-standing iscsi-target bug-fix for duplicate target_xfer_tags
  during NOP processing from Alexei, and two more small REPORT_LUNs
  emulation related patches to make Solaris FC host LUN scanning happy
  from Roland.

  There is also one patch not included that allows target-core to limit
  the number of fabric driver SGLs per I/O request using residuals, that
  is currently required as a work-around for FC hosts which don't honor
  EVPD block-limits settings.  At this point, it will most likely become
  for-next material"

* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
  target: Fix handling of small allocation lengths in REPORT LUNS
  target: REPORT LUNS should return LUN 0 even for dynamic ACLs
  target/iscsi: Fix double free of a TUR followed by a solicited NOPOUT
  target: Perform RCU callback barrier before backend/fabric unload

drivers/target/iscsi/iscsi_target.c

@@ -968,9 +968,9 @@ int iscsit_setup_scsi_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 		cmd->cmd_flags |= ICF_NON_IMMEDIATE_UNSOLICITED_DATA;
 
 	conn->sess->init_task_tag = cmd->init_task_tag = hdr->itt;
-	if (hdr->flags & ISCSI_FLAG_CMD_READ) {
+	if (hdr->flags & ISCSI_FLAG_CMD_READ)
 		cmd->targ_xfer_tag = session_get_next_ttt(conn->sess);
-	} else if (hdr->flags & ISCSI_FLAG_CMD_WRITE)
+	else
 		cmd->targ_xfer_tag = 0xFFFFFFFF;
 	cmd->cmd_sn		= be32_to_cpu(hdr->cmdsn);
 	cmd->exp_stat_sn	= be32_to_cpu(hdr->exp_statsn);

drivers/target/target_core_configfs.c

@@ -457,8 +457,15 @@ void target_unregister_template(const struct target_core_fabric_ops *fo)
 		if (!strcmp(t->tf_ops->name, fo->name)) {
 			BUG_ON(atomic_read(&t->tf_access_cnt));
 			list_del(&t->tf_list);
+			mutex_unlock(&g_tf_lock);
+			/*
+			 * Wait for any outstanding fabric se_deve_entry->rcu_head
+			 * callbacks to complete post kfree_rcu(), before allowing
+			 * fabric driver unload of TFO->module to proceed.
+			 */
+			rcu_barrier();
 			kfree(t);
-			break;
+			return;
 		}
 	}
 	mutex_unlock(&g_tf_lock);

drivers/target/target_core_hba.c

@@ -84,8 +84,16 @@ void target_backend_unregister(const struct target_backend_ops *ops)
 	list_for_each_entry(tb, &backend_list, list) {
 		if (tb->ops == ops) {
 			list_del(&tb->list);
+			mutex_unlock(&backend_mutex);
+			/*
+			 * Wait for any outstanding backend driver ->rcu_head
+			 * callbacks to complete post TBO->free_device() ->
+			 * call_rcu(), before allowing backend driver module
+			 * unload of target_backend_ops->owner to proceed.
+			 */
+			rcu_barrier();
 			kfree(tb);
-			break;
+			return;
 		}
 	}
 	mutex_unlock(&backend_mutex);

drivers/target/target_core_spc.c

@@ -1203,29 +1203,23 @@ sense_reason_t spc_emulate_report_luns(struct se_cmd *cmd)
 	struct se_dev_entry *deve;
 	struct se_session *sess = cmd->se_sess;
 	struct se_node_acl *nacl;
+	struct scsi_lun slun;
 	unsigned char *buf;
 	u32 lun_count = 0, offset = 8;
-
-	if (cmd->data_length < 16) {
-		pr_warn("REPORT LUNS allocation length %u too small\n",
-			cmd->data_length);
-		return TCM_INVALID_CDB_FIELD;
-	}
+	__be32 len;
 
 	buf = transport_kmap_data_sg(cmd);
-	if (!buf)
+	if (cmd->data_length && !buf)
 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
 	/*
 	 * If no struct se_session pointer is present, this struct se_cmd is
 	 * coming via a target_core_mod PASSTHROUGH op, and not through
 	 * a $FABRIC_MOD.  In that case, report LUN=0 only.
 	 */
-	if (!sess) {
-		int_to_scsilun(0, (struct scsi_lun *)&buf[offset]);
-		lun_count = 1;
+	if (!sess)
 		goto done;
-	}
+
 	nacl = sess->se_node_acl;
 
 	rcu_read_lock();
@@ -1236,10 +1230,12 @@ sense_reason_t spc_emulate_report_luns(struct se_cmd *cmd)
 		 * See SPC2-R20 7.19.
 		 */
 		lun_count++;
-		if ((offset + 8) > cmd->data_length)
+		if (offset >= cmd->data_length)
 			continue;
 
-		int_to_scsilun(deve->mapped_lun, (struct scsi_lun *)&buf[offset]);
+		int_to_scsilun(deve->mapped_lun, &slun);
+		memcpy(buf + offset, &slun,
+		       min(8u, cmd->data_length - offset));
 		offset += 8;
 	}
 	rcu_read_unlock();
@@ -1248,12 +1244,22 @@ sense_reason_t spc_emulate_report_luns(struct se_cmd *cmd)
 	 * See SPC3 r07, page 159.
 	 */
 done:
-	lun_count *= 8;
-	buf[0] = ((lun_count >> 24) & 0xff);
-	buf[1] = ((lun_count >> 16) & 0xff);
-	buf[2] = ((lun_count >> 8) & 0xff);
-	buf[3] = (lun_count & 0xff);
-	transport_kunmap_data_sg(cmd);
+	/*
+	 * If no LUNs are accessible, report virtual LUN 0.
+	 */
+	if (lun_count == 0) {
+		int_to_scsilun(0, &slun);
+		if (cmd->data_length > 8)
+			memcpy(buf + offset, &slun,
+			       min(8u, cmd->data_length - offset));
+		lun_count = 1;
+	}
+
+	if (buf) {
+		len = cpu_to_be32(lun_count * 8);
+		memcpy(buf, &len, min_t(int, sizeof len, cmd->data_length));
+		transport_kunmap_data_sg(cmd);
+	}
 
 	target_complete_cmd_with_length(cmd, GOOD, 8 + lun_count * 8);
 	return 0;