scsi: scsi_transport_fc: Add an additional flag to fc_host_fpin_rcv()

The LLDD and the stack currently process FPINs received from the fabric,
but the stack is not aware of any action taken by the driver to alleviate
congestion. The current interface between the driver and the SCSI stack is
limited to passing the notification mainly for statistics and heuristics.

The reaction to an FPIN could be handled either by the driver or by the
stack (marginal path and failover). Amend the interface to indicate if
action on an FPIN has already been reacted to by the LLDDs or not. Add an
additional flag to fc_host_fpin_rcv() to indicate if the FPIN has been
acknowledged/reacted to by the driver.

Also added a new event code FCH_EVT_LINK_FPIN_ACK to notify to the user
that the event has been acknowledged/reacted by the LLDD driver

Link: https://lore.kernel.org/r/20230209034326.882514-1-muneendra.kumar@broadcom.comCo-developed-by: NAnil Gurumurthy <agurumurthy@marvell.com>
Signed-off-by: NAnil Gurumurthy <agurumurthy@marvell.com>
Co-developed-by: NNilesh Javali <njavali@marvell.com>
Signed-off-by: NNilesh Javali <njavali@marvell.com>
Signed-off-by: NMuneendra <muneendra.kumar@broadcom.com>
Reviewed-by: NJames Smart <jsmart2021@gmail.com>
Reviewed-by: NHimanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: NEwan D. Milne <emilne@redhat.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_els.c

@@ -10287,7 +10287,7 @@ lpfc_els_rcv_fpin(struct lpfc_vport *vport, void *p, u32 fpin_length)
 		/* Send every descriptor individually to the upper layer */
 		if (deliver)
 			fc_host_fpin_rcv(lpfc_shost_from_vport(vport),
-					 fpin_length, (char *)fpin);
+					 fpin_length, (char *)fpin, 0);
 		desc_cnt++;
 	}
 }

drivers/scsi/qla2xxx/qla_isr.c

@@ -45,7 +45,7 @@ qla27xx_process_purex_fpin(struct scsi_qla_host *vha, struct purex_item *item)
 	ql_dump_buffer(ql_dbg_init + ql_dbg_verbose, vha, 0x508f,
 		       pkt, pkt_size);
 
-	fc_host_fpin_rcv(vha->host, pkt_size, (char *)pkt);
+	fc_host_fpin_rcv(vha->host, pkt_size, (char *)pkt, 0);
 }
 
 const char *const port_state_str[] = {

drivers/scsi/scsi_transport_fc.c

@@ -137,6 +137,7 @@ static const struct {
 	{ FCH_EVT_PORT_FABRIC,		"port_fabric" },
 	{ FCH_EVT_LINK_UNKNOWN,		"link_unknown" },
 	{ FCH_EVT_LINK_FPIN,		"link_FPIN" },
+	{ FCH_EVT_LINK_FPIN_ACK,	"link_FPIN_ACK" },
 	{ FCH_EVT_VENDOR_UNIQUE,	"vendor_unique" },
 };
 fc_enum_name_search(host_event_code, fc_host_event_code,
@@ -894,17 +895,20 @@ fc_fpin_congn_stats_update(struct Scsi_Host *shost,
  * @shost:		host the FPIN was received on
  * @fpin_len:		length of FPIN payload, in bytes
  * @fpin_buf:		pointer to FPIN payload
- *
+ * @event_acknowledge:	1, if LLDD handles this event.
  * Notes:
  *	This routine assumes no locks are held on entry.
  */
 void
-fc_host_fpin_rcv(struct Scsi_Host *shost, u32 fpin_len, char *fpin_buf)
+fc_host_fpin_rcv(struct Scsi_Host *shost, u32 fpin_len, char *fpin_buf,
+		u8 event_acknowledge)
 {
 	struct fc_els_fpin *fpin = (struct fc_els_fpin *)fpin_buf;
 	struct fc_tlv_desc *tlv;
 	u32 desc_cnt = 0, bytes_remain;
 	u32 dtag;
+	enum fc_host_event_code event_code =
+		event_acknowledge ? FCH_EVT_LINK_FPIN_ACK : FCH_EVT_LINK_FPIN;
 
 	/* Update Statistics */
 	tlv = (struct fc_tlv_desc *)&fpin->fpin_desc[0];
@@ -934,7 +938,7 @@ fc_host_fpin_rcv(struct Scsi_Host *shost, u32 fpin_len, char *fpin_buf)
 	}
 
 	fc_host_post_fc_event(shost, fc_get_event_number(),
-				FCH_EVT_LINK_FPIN, fpin_len, fpin_buf, 0);
+				event_code, fpin_len, fpin_buf, 0);
 }
 EXPORT_SYMBOL(fc_host_fpin_rcv);
 

include/scsi/scsi_transport_fc.h

@@ -496,6 +496,7 @@ enum fc_host_event_code  {
 	FCH_EVT_PORT_FABRIC		= 0x204,
 	FCH_EVT_LINK_UNKNOWN		= 0x500,
 	FCH_EVT_LINK_FPIN		= 0x501,
+	FCH_EVT_LINK_FPIN_ACK		= 0x502,
 	FCH_EVT_VENDOR_UNIQUE		= 0xffff,
 };
 
@@ -856,7 +857,8 @@ void fc_host_post_fc_event(struct Scsi_Host *shost, u32 event_number,
 	 * Note: when calling fc_host_post_fc_event(), vendor_id may be
 	 *   specified as 0.
 	 */
-void fc_host_fpin_rcv(struct Scsi_Host *shost, u32 fpin_len, char *fpin_buf);
+void fc_host_fpin_rcv(struct Scsi_Host *shost, u32 fpin_len, char *fpin_buf,
+		u8 event_acknowledge);
 struct fc_vport *fc_vport_create(struct Scsi_Host *shost, int channel,
 		struct fc_vport_identifiers *);
 int fc_vport_terminate(struct fc_vport *vport);