[PATCH v2 15/15] scsi: qla2xxx: Handle ABTS according to FCP spec for logged out ports

[Roman Bolshakov <r.bolshakov@xxxxxxxxx>]

Fibre Channel Protocol for SCSI, Fourth Version (FCP-4) 12.3.3, "Target
FCP_Port response to Exchange termination" states:

  When an ABTS-LS is received at the target FCP_Port, it shall abort the
  designated Exchange and return one of the following responses:

    a) the target FCP_Port shall discard the ABTS-LS and transmit a LOGO ELS if
       the Nx_Port issuing the ABTS-LS is not currently logged in (i.e., no
       N_Port Login exists);

However, current implementation tries to send a real BA_RJT in response to ABTS
from logged-out ports. The oparation fails because N_Port handle was freed
shortly after logout and ABTS Recieved IOCB contains 0xFFFF N_Port handle.
Existing implementation doesn't send LOGO at all.

The correct way to discard ABTS-LS frame when N_Port handle wasn't found is to
set Terminate ABTS Exchange bit in control flags of ABTS Response IOCB.
LOGO is sent after that.

To avoid a deadlock in qla2x00_start_sp(), hardware_lock should be released.
The unlocking should be safe because ABTS Recieved IOCB is not needed after
s_id is saved on the stack and qlt_24xx_send_abts_resp() is invoked.

Fixes: 2d70c103fd2a ("[SCSI] qla2xxx: Add LLD target-mode infrastructure for >= 24xx series")
Cc: Quinn Tran <qutran@xxxxxxxxxxx>
Cc: Himanshu Madhani <hmadhani@xxxxxxxxxxx>
Signed-off-by: Roman Bolshakov <r.bolshakov@xxxxxxxxx>
---
 drivers/scsi/qla2xxx/qla_target.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index 0f2bc4cd562f..331e7adf4b15 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -1800,7 +1800,7 @@ static int qlt_build_abts_resp_iocb(struct qla_tgt_mgmt_cmd *mcmd)
  */
 static void qlt_24xx_send_abts_resp(struct qla_qpair *qpair,
 	struct abts_recv_from_24xx *abts, uint32_t status,
-	bool ids_reversed)
+	bool ids_reversed, bool term_exchange)
 {
 	struct scsi_qla_host *vha = qpair->vha;
 	struct qla_hw_data *ha = vha->hw;
@@ -1825,6 +1825,10 @@ static void qlt_24xx_send_abts_resp(struct qla_qpair *qpair,
 	resp->handle = QLA_TGT_SKIP_HANDLE;
 	resp->entry_count = 1;
 	resp->nport_handle = abts->nport_handle;
+	if (term_exchange)
+		resp->control_flags = cpu_to_le16(ABTS_CONTR_FLG_TERM_EXCHG);
+	else
+		resp->control_flags = 0;
 	resp->vp_index = vha->vp_idx;
 	resp->sof_type = abts->sof_type;
 	resp->exchange_address = abts->exchange_address;
@@ -1940,7 +1944,7 @@ static void qlt_24xx_retry_term_exchange(struct scsi_qla_host *vha,
 		qlt_build_abts_resp_iocb(mcmd);
 	else
 		qlt_24xx_send_abts_resp(qpair,
-		    (struct abts_recv_from_24xx *)entry, FCP_TMF_CMPL, true);
+		    (struct abts_recv_from_24xx *)entry, FCP_TMF_CMPL, true, false);
 
 }
 
@@ -2134,7 +2138,7 @@ static void qlt_24xx_handle_abts(struct scsi_qla_host *vha,
 		    "qla_target(%d): ABTS: Abort Sequence not "
 		    "supported\n", vha->vp_idx);
 		qlt_24xx_send_abts_resp(ha->base_qpair, abts, FCP_TMF_REJECTED,
-		    false);
+		    false, false);
 		return;
 	}
 
@@ -2143,7 +2147,7 @@ static void qlt_24xx_handle_abts(struct scsi_qla_host *vha,
 		    "qla_target(%d): ABTS: Unknown Exchange "
 		    "Address received\n", vha->vp_idx);
 		qlt_24xx_send_abts_resp(ha->base_qpair, abts, FCP_TMF_REJECTED,
-		    false);
+		    false, false);
 		return;
 	}
 
@@ -2163,8 +2167,16 @@ static void qlt_24xx_handle_abts(struct scsi_qla_host *vha,
 		    vha->vp_idx);
 		spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
 
+		/*
+		 * According to FCP-4 12.3.3,
+		 * ABTS-LS frame shall be discarded
+		 */
 		qlt_24xx_send_abts_resp(ha->base_qpair, abts, FCP_TMF_REJECTED,
-			    false);
+			    false, true);
+		spin_unlock_irqrestore(&ha->hardware_lock, flags);
+		/* and LOGO ELS transmitted */
+		qla24xx_els_dcmd_iocb(vha, ELS_DCMD_LOGO, be_to_port_id(s_id), false);
+		spin_lock_irqsave(&ha->hardware_lock, flags);
 		return;
 	}
 	spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
@@ -2172,7 +2184,7 @@ static void qlt_24xx_handle_abts(struct scsi_qla_host *vha,
 
 	if (sess->deleted) {
 		qlt_24xx_send_abts_resp(ha->base_qpair, abts, FCP_TMF_REJECTED,
-		    false);
+		    false, false);
 		return;
 	}
 
@@ -2182,7 +2194,7 @@ static void qlt_24xx_handle_abts(struct scsi_qla_host *vha,
 		    "qla_target(%d): __qlt_24xx_handle_abts() failed: %d\n",
 		    vha->vp_idx, rc);
 		qlt_24xx_send_abts_resp(ha->base_qpair, abts, FCP_TMF_REJECTED,
-		    false);
+		    false, false);
 		return;
 	}
 }
@@ -6213,7 +6225,7 @@ static void qlt_abort_work(struct qla_tgt *tgt,
 out_term:
 	spin_lock_irqsave(&ha->hardware_lock, flags);
 	qlt_24xx_send_abts_resp(ha->base_qpair, &prm->abts,
-	    FCP_TMF_REJECTED, false);
+	    FCP_TMF_REJECTED, false, false);
 	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 }
 
-- 
2.24.0