iscsi-target: Refactor TX queue logic + export response PDU creation

This patch refactors TX immediate + response queue handling to use
the new iscsit_transport API callers, and exports the necessary
traditional iscsi PDU response creation functions for iser-target
to utilize.

This includes:

- Add iscsit_build_datain_pdu() for DATAIN PDU init + convert
  iscsit_build_datain_pdu()
- Add iscsit_build_logout_rsp() for LOGOUT_RSP PDU init + convert
  iscsit_send_logout()
- Add iscsit_build_nopin_rsp() for NOPIN_RSP PDU init + convert
  iscsit_send_nopin()
- Add iscsit_build_rsp_pdu() for SCSI_RSP PDU init + convert
  iscsit_send_response()
- Add iscsit_build_task_mgt_rsp for TM_RSP PDU init + convert
  iscsit_send_task_mgt_rsp()
- Refactor immediate queue state switch into iscsit_immediate_queue()
- Convert handle_immediate_queue() to use iscsit_transport caller
- Refactor response queue state switch into iscsit_response_queue()
- Convert handle_response_queue to use iscsit_transport caller
- Export iscsit_logout_post_handler(), iscsit_increment_maxcmdsn()
  and iscsit_tmr_post_handler() for external transport module usage

v5 changes:

- Fix solicited NopIN handling with RDMAExtensions=No (nab)

v3 changes:
- Add iscsit_build_reject for REJECT PDU init + convert
  iscsit_send_reject()

v2 changes:

- Add iscsit_queue_rsp() for iscsit_transport->iscsit_queue_data_in()
  and iscsit_transport->iscsit_queue_status()
- Update lio_queue_data_in() to use ->iscsit_queue_data_in()
- Update lio_queue_status() to use ->iscsit_queue_status()
- Use mutex_trylock() in iscsit_increment_maxcmdsn()

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/target/iscsi/iscsi_target_device.c b/drivers/target/iscsi/iscsi_target_device.c
index bcc409853a67..1b74033510a0 100644
--- a/drivers/target/iscsi/iscsi_target_device.c
+++ b/drivers/target/iscsi/iscsi_target_device.c
@@ -60,8 +60,13 @@ void iscsit_increment_maxcmdsn(struct iscsi_cmd *cmd, struct iscsi_session *sess
 
 	cmd->maxcmdsn_inc = 1;
 
-	mutex_lock(&sess->cmdsn_mutex);
+	if (!mutex_trylock(&sess->cmdsn_mutex)) {
+		sess->max_cmd_sn += 1;
+		pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn);
+		return;
+	}
 	sess->max_cmd_sn += 1;
 	pr_debug("Updated MaxCmdSN to 0x%08x\n", sess->max_cmd_sn);
 	mutex_unlock(&sess->cmdsn_mutex);
 }
+EXPORT_SYMBOL(iscsit_increment_maxcmdsn);