scsi: qla2xxx: Fix exchange oversubscription

In large environment, it is possible to experience command timeout and
escalation of path recovery. Currently the driver does not track the number
of exchanges/commands sent to FW. If there is a delay for commands at the
head of the queue, then this will create back pressure for commands at the
back of the queue.

Check for exchange availability before command submission.

Fixes: 89c72f4245a8 ("scsi: qla2xxx: Add IOCB resource tracking")
Signed-off-by: Quinn Tran <qutran@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

7 files changed, 88 insertions, 36 deletions

diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
index a26a373be9da..cd4eb11b0707 100644
--- a/drivers/scsi/qla2xxx/qla_def.h
+++ b/drivers/scsi/qla2xxx/qla_def.h
@@ -660,7 +660,7 @@ enum {
 
 struct iocb_resource {
 	u8 res_type;
-	u8 pad;
+	u8  exch_cnt;
 	u16 iocb_cnt;
 };
 
@@ -3721,6 +3721,10 @@ struct qla_fw_resources {
 	u16 iocbs_limit;
 	u16 iocbs_qp_limit;
 	u16 iocbs_used;
+	u16 exch_total;
+	u16 exch_limit;
+	u16 exch_used;
+	u16 pad;
 };
 
 #define QLA_IOCB_PCT_LIMIT 95
diff --git a/drivers/scsi/qla2xxx/qla_edif.c b/drivers/scsi/qla2xxx/qla_edif.c
index e4240aae5f9e..53186a145962 100644
--- a/drivers/scsi/qla2xxx/qla_edif.c
+++ b/drivers/scsi/qla2xxx/qla_edif.c
@@ -2989,9 +2989,10 @@ qla28xx_start_scsi_edif(srb_t *sp)
 	tot_dsds = nseg;
 	req_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
 
-	sp->iores.res_type = RESOURCE_INI;
+	sp->iores.res_type = RESOURCE_IOCB | RESOURCE_EXCH;
+	sp->iores.exch_cnt = 1;
 	sp->iores.iocb_cnt = req_cnt;
-	if (qla_get_iocbs(sp->qpair, &sp->iores))
+	if (qla_get_fw_resources(sp->qpair, &sp->iores))
 		goto queuing_error;
 
 	if (req->cnt < (req_cnt + 2)) {
@@ -3185,7 +3186,7 @@ queuing_error:
 		mempool_free(sp->u.scmd.ct6_ctx, ha->ctx_mempool);
 		sp->u.scmd.ct6_ctx = NULL;
 	}
-	qla_put_iocbs(sp->qpair, &sp->iores);
+	qla_put_fw_resources(sp->qpair, &sp->iores);
 	spin_unlock_irqrestore(lock, flags);
 
 	return QLA_FUNCTION_FAILED;
diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index 8d9ecabb1aac..fd27fb511479 100644
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -128,12 +128,14 @@ static void qla24xx_abort_iocb_timeout(void *data)
 		    sp->cmd_sp)) {
 			qpair->req->outstanding_cmds[handle] = NULL;
 			cmdsp_found = 1;
+			qla_put_fw_resources(qpair, &sp->cmd_sp->iores);
 		}
 
 		/* removing the abort */
 		if (qpair->req->outstanding_cmds[handle] == sp) {
 			qpair->req->outstanding_cmds[handle] = NULL;
 			sp_found = 1;
+			qla_put_fw_resources(qpair, &sp->iores);
 			break;
 		}
 	}
@@ -2000,6 +2002,7 @@ qla2x00_tmf_iocb_timeout(void *data)
 		for (h = 1; h < sp->qpair->req->num_outstanding_cmds; h++) {
 			if (sp->qpair->req->outstanding_cmds[h] == sp) {
 				sp->qpair->req->outstanding_cmds[h] = NULL;
+				qla_put_fw_resources(sp->qpair, &sp->iores);
 				break;
 			}
 		}
@@ -3943,6 +3946,12 @@ void qla_init_iocb_limit(scsi_qla_host_t *vha)
 	ha->base_qpair->fwres.iocbs_limit = limit;
 	ha->base_qpair->fwres.iocbs_qp_limit = limit / num_qps;
 	ha->base_qpair->fwres.iocbs_used = 0;
+
+	ha->base_qpair->fwres.exch_total = ha->orig_fw_xcb_count;
+	ha->base_qpair->fwres.exch_limit = (ha->orig_fw_xcb_count *
+					    QLA_IOCB_PCT_LIMIT) / 100;
+	ha->base_qpair->fwres.exch_used  = 0;
+
 	for (i = 0; i < ha->max_qpairs; i++) {
 		if (ha->queue_pair_map[i])  {
 			ha->queue_pair_map[i]->fwres.iocbs_total =
@@ -3951,6 +3960,10 @@ void qla_init_iocb_limit(scsi_qla_host_t *vha)
 			ha->queue_pair_map[i]->fwres.iocbs_qp_limit =
 				limit / num_qps;
 			ha->queue_pair_map[i]->fwres.iocbs_used = 0;
+			ha->queue_pair_map[i]->fwres.exch_total = ha->orig_fw_xcb_count;
+			ha->queue_pair_map[i]->fwres.exch_limit =
+				(ha->orig_fw_xcb_count * QLA_IOCB_PCT_LIMIT) / 100;
+			ha->queue_pair_map[i]->fwres.exch_used = 0;
 		}
 	}
 }
diff --git a/drivers/scsi/qla2xxx/qla_inline.h b/drivers/scsi/qla2xxx/qla_inline.h
index 5185dc5daf80..2d5a275d8b00 100644
--- a/drivers/scsi/qla2xxx/qla_inline.h
+++ b/drivers/scsi/qla2xxx/qla_inline.h
@@ -380,13 +380,16 @@ qla2xxx_get_fc4_priority(struct scsi_qla_host *vha)
 
 enum {
 	RESOURCE_NONE,
-	RESOURCE_INI,
+	RESOURCE_IOCB  = BIT_0,
+	RESOURCE_EXCH = BIT_1,  /* exchange */
+	RESOURCE_FORCE = BIT_2,
 };
 
 static inline int
-qla_get_iocbs(struct qla_qpair *qp, struct iocb_resource *iores)
+qla_get_fw_resources(struct qla_qpair *qp, struct iocb_resource *iores)
 {
 	u16 iocbs_used, i;
+	u16 exch_used;
 	struct qla_hw_data *ha = qp->vha->hw;
 
 	if (!ql2xenforce_iocb_limit) {
@@ -394,10 +397,7 @@ qla_get_iocbs(struct qla_qpair *qp, struct iocb_resource *iores)
 		return 0;
 	}
 
-	if ((iores->iocb_cnt + qp->fwres.iocbs_used) < qp->fwres.iocbs_qp_limit) {
-		qp->fwres.iocbs_used += iores->iocb_cnt;
-		return 0;
-	} else {
+	if ((iores->iocb_cnt + qp->fwres.iocbs_used) >= qp->fwres.iocbs_qp_limit) {
 		/* no need to acquire qpair lock. It's just rough calculation */
 		iocbs_used = ha->base_qpair->fwres.iocbs_used;
 		for (i = 0; i < ha->max_qpairs; i++) {
@@ -405,30 +405,48 @@ qla_get_iocbs(struct qla_qpair *qp, struct iocb_resource *iores)
 				iocbs_used += ha->queue_pair_map[i]->fwres.iocbs_used;
 		}
 
-		if ((iores->iocb_cnt + iocbs_used) < qp->fwres.iocbs_limit) {
-			qp->fwres.iocbs_used += iores->iocb_cnt;
-			return 0;
-		} else {
+		if ((iores->iocb_cnt + iocbs_used) >= qp->fwres.iocbs_limit) {
+			iores->res_type = RESOURCE_NONE;
+			return -ENOSPC;
+		}
+	}
+
+	if (iores->res_type & RESOURCE_EXCH) {
+		exch_used = ha->base_qpair->fwres.exch_used;
+		for (i = 0; i < ha->max_qpairs; i++) {
+			if (ha->queue_pair_map[i])
+				exch_used += ha->queue_pair_map[i]->fwres.exch_used;
+		}
+
+		if ((exch_used + iores->exch_cnt) >= qp->fwres.exch_limit) {
 			iores->res_type = RESOURCE_NONE;
 			return -ENOSPC;
 		}
 	}
+	qp->fwres.iocbs_used += iores->iocb_cnt;
+	qp->fwres.exch_used += iores->exch_cnt;
+	return 0;
 }
 
 static inline void
-qla_put_iocbs(struct qla_qpair *qp, struct iocb_resource *iores)
+qla_put_fw_resources(struct qla_qpair *qp, struct iocb_resource *iores)
 {
-	switch (iores->res_type) {
-	case RESOURCE_NONE:
-		break;
-	default:
+	if (iores->res_type & RESOURCE_IOCB) {
 		if (qp->fwres.iocbs_used >= iores->iocb_cnt) {
 			qp->fwres.iocbs_used -= iores->iocb_cnt;
 		} else {
-			// should not happen
+			/* should not happen */
 			qp->fwres.iocbs_used = 0;
 		}
-		break;
+	}
+
+	if (iores->res_type & RESOURCE_EXCH) {
+		if (qp->fwres.exch_used >= iores->exch_cnt) {
+			qp->fwres.exch_used -= iores->exch_cnt;
+		} else {
+			/* should not happen */
+			qp->fwres.exch_used = 0;
+		}
 	}
 	iores->res_type = RESOURCE_NONE;
 }
diff --git a/drivers/scsi/qla2xxx/qla_iocb.c b/drivers/scsi/qla2xxx/qla_iocb.c
index 42ce4e1fe744..399ec8da2d73 100644
--- a/drivers/scsi/qla2xxx/qla_iocb.c
+++ b/drivers/scsi/qla2xxx/qla_iocb.c
@@ -1589,9 +1589,10 @@ qla24xx_start_scsi(srb_t *sp)
 	tot_dsds = nseg;
 	req_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
 
-	sp->iores.res_type = RESOURCE_INI;
+	sp->iores.res_type = RESOURCE_IOCB | RESOURCE_EXCH;
+	sp->iores.exch_cnt = 1;
 	sp->iores.iocb_cnt = req_cnt;
-	if (qla_get_iocbs(sp->qpair, &sp->iores))
+	if (qla_get_fw_resources(sp->qpair, &sp->iores))
 		goto queuing_error;
 
 	if (req->cnt < (req_cnt + 2)) {
@@ -1678,7 +1679,7 @@ queuing_error:
 	if (tot_dsds)
 		scsi_dma_unmap(cmd);
 
-	qla_put_iocbs(sp->qpair, &sp->iores);
+	qla_put_fw_resources(sp->qpair, &sp->iores);
 	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
 	return QLA_FUNCTION_FAILED;
@@ -1793,9 +1794,10 @@ qla24xx_dif_start_scsi(srb_t *sp)
 	tot_prot_dsds = nseg;
 	tot_dsds += nseg;
 
-	sp->iores.res_type = RESOURCE_INI;
+	sp->iores.res_type = RESOURCE_IOCB | RESOURCE_EXCH;
+	sp->iores.exch_cnt = 1;
 	sp->iores.iocb_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
-	if (qla_get_iocbs(sp->qpair, &sp->iores))
+	if (qla_get_fw_resources(sp->qpair, &sp->iores))
 		goto queuing_error;
 
 	if (req->cnt < (req_cnt + 2)) {
@@ -1883,7 +1885,7 @@ queuing_error:
 	}
 	/* Cleanup will be performed by the caller (queuecommand) */
 
-	qla_put_iocbs(sp->qpair, &sp->iores);
+	qla_put_fw_resources(sp->qpair, &sp->iores);
 	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
 	return QLA_FUNCTION_FAILED;
@@ -1952,9 +1954,10 @@ qla2xxx_start_scsi_mq(srb_t *sp)
 	tot_dsds = nseg;
 	req_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
 
-	sp->iores.res_type = RESOURCE_INI;
+	sp->iores.res_type = RESOURCE_IOCB | RESOURCE_EXCH;
+	sp->iores.exch_cnt = 1;
 	sp->iores.iocb_cnt = req_cnt;
-	if (qla_get_iocbs(sp->qpair, &sp->iores))
+	if (qla_get_fw_resources(sp->qpair, &sp->iores))
 		goto queuing_error;
 
 	if (req->cnt < (req_cnt + 2)) {
@@ -2041,7 +2044,7 @@ queuing_error:
 	if (tot_dsds)
 		scsi_dma_unmap(cmd);
 
-	qla_put_iocbs(sp->qpair, &sp->iores);
+	qla_put_fw_resources(sp->qpair, &sp->iores);
 	spin_unlock_irqrestore(&qpair->qp_lock, flags);
 
 	return QLA_FUNCTION_FAILED;
@@ -2171,9 +2174,10 @@ qla2xxx_dif_start_scsi_mq(srb_t *sp)
 	tot_prot_dsds = nseg;
 	tot_dsds += nseg;
 
-	sp->iores.res_type = RESOURCE_INI;
+	sp->iores.res_type = RESOURCE_IOCB | RESOURCE_EXCH;
+	sp->iores.exch_cnt = 1;
 	sp->iores.iocb_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
-	if (qla_get_iocbs(sp->qpair, &sp->iores))
+	if (qla_get_fw_resources(sp->qpair, &sp->iores))
 		goto queuing_error;
 
 	if (req->cnt < (req_cnt + 2)) {
@@ -2260,7 +2264,7 @@ queuing_error:
 	}
 	/* Cleanup will be performed by the caller (queuecommand) */
 
-	qla_put_iocbs(sp->qpair, &sp->iores);
+	qla_put_fw_resources(sp->qpair, &sp->iores);
 	spin_unlock_irqrestore(&qpair->qp_lock, flags);
 
 	return QLA_FUNCTION_FAILED;
diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
index e19fde304e5c..42d3d2de3d31 100644
--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -3197,7 +3197,7 @@ qla2x00_status_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, void *pkt)
 		}
 		return;
 	}
-	qla_put_iocbs(sp->qpair, &sp->iores);
+	qla_put_fw_resources(sp->qpair, &sp->iores);
 
 	if (sp->cmd_type != TYPE_SRB) {
 		req->outstanding_cmds[handle] = NULL;
@@ -3618,7 +3618,6 @@ qla2x00_error_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, sts_entry_t *pkt)
 	default:
 		sp = qla2x00_get_sp_from_handle(vha, func, req, pkt);
 		if (sp) {
-			qla_put_iocbs(sp->qpair, &sp->iores);
 			sp->done(sp, res);
 			return 0;
 		}
diff --git a/drivers/scsi/qla2xxx/qla_nvme.c b/drivers/scsi/qla2xxx/qla_nvme.c
index 8927ddc5e69c..c57e02a35521 100644
--- a/drivers/scsi/qla2xxx/qla_nvme.c
+++ b/drivers/scsi/qla2xxx/qla_nvme.c
@@ -428,13 +428,24 @@ static inline int qla2x00_start_nvme_mq(srb_t *sp)
 		goto queuing_error;
 	}
 	req_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
+
+	sp->iores.res_type = RESOURCE_IOCB | RESOURCE_EXCH;
+	sp->iores.exch_cnt = 1;
+	sp->iores.iocb_cnt = req_cnt;
+	if (qla_get_fw_resources(sp->qpair, &sp->iores)) {
+		rval = -EBUSY;
+		goto queuing_error;
+	}
+
 	if (req->cnt < (req_cnt + 2)) {
 		if (IS_SHADOW_REG_CAPABLE(ha)) {
 			cnt = *req->out_ptr;
 		} else {
 			cnt = rd_reg_dword_relaxed(req->req_q_out);
-			if (qla2x00_check_reg16_for_disconnect(vha, cnt))
+			if (qla2x00_check_reg16_for_disconnect(vha, cnt)) {
+				rval = -EBUSY;
 				goto queuing_error;
+			}
 		}
 
 		if (req->ring_index < cnt)
@@ -583,6 +594,8 @@ static inline int qla2x00_start_nvme_mq(srb_t *sp)
 		qla24xx_process_response_queue(vha, rsp);
 
 queuing_error:
+	if (rval)
+		qla_put_fw_resources(sp->qpair, &sp->iores);
 	spin_unlock_irqrestore(&qpair->qp_lock, flags);
 
 	return rval;