scsi: qla2xxx: edif: Fix performance dip due to lock contention

User experienced performance dip on measuring IOPS while EDIF
enabled. During I/O time, driver uses dma_pool_zalloc() call to allocate a
chunk of memory. This call contains a lock behind the scene which
contribute to lock contention. Save the allocated memory for reuse and
avoid the lock.

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>

drivers/scsi/qla2xxx/qla_def.h

@@ -384,6 +384,13 @@ struct els_reject {
 struct req_que;
 struct qla_tgt_sess;
 
+struct qla_buf_dsc {
+	u16 tag;
+#define TAG_FREED 0xffff
+	void *buf;
+	dma_addr_t buf_dma;
+};
+
 /*
  * SCSI Request Block
  */
@@ -392,14 +399,16 @@ struct srb_cmd {
 	uint32_t request_sense_length;
 	uint32_t fw_sense_length;
 	uint8_t *request_sense_ptr;
-	struct ct6_dsd *ct6_ctx;
 	struct crc_context *crc_ctx;
+	struct ct6_dsd ct6_ctx;
+	struct qla_buf_dsc buf_dsc;
 };
 
 /*
  * SRB flag definitions
  */
 #define SRB_DMA_VALID			BIT_0	/* Command sent to ISP */
+#define SRB_GOT_BUF			BIT_1
 #define SRB_FCP_CMND_DMA_VALID		BIT_12	/* DIF: DSD List valid */
 #define SRB_CRC_CTX_DMA_VALID		BIT_2	/* DIF: context DMA valid */
 #define SRB_CRC_PROT_DMA_VALID		BIT_4	/* DIF: prot DMA valid */
@@ -3722,6 +3731,16 @@ struct qla_fw_resources {
 
 #define QLA_IOCB_PCT_LIMIT 95
 
+struct  qla_buf_pool {
+	u16 num_bufs;
+	u16 num_active;
+	u16 max_used;
+	u16 reserved;
+	unsigned long *buf_map;
+	void **buf_array;
+	dma_addr_t *dma_array;
+};
+
 /*Queue pair data structure */
 struct qla_qpair {
 	spinlock_t qp_lock;
@@ -3775,6 +3794,7 @@ struct qla_qpair {
 	struct qla_tgt_counters tgt_counters;
 	uint16_t cpuid;
 	struct qla_fw_resources fwres ____cacheline_aligned;
+	struct  qla_buf_pool buf_pool;
 	u32	cmd_cnt;
 	u32	cmd_completion_cnt;
 	u32	prev_completion_cnt;

drivers/scsi/qla2xxx/qla_edif.c

@@ -3007,26 +3007,16 @@ qla28xx_start_scsi_edif(srb_t *sp)
 			goto queuing_error;
 	}
 
-	ctx = sp->u.scmd.ct6_ctx =
-	    mempool_alloc(ha->ctx_mempool, GFP_ATOMIC);
-	if (!ctx) {
-		ql_log(ql_log_fatal, vha, 0x3010,
-		    "Failed to allocate ctx for cmd=%p.\n", cmd);
-		goto queuing_error;
-	}
-
-	memset(ctx, 0, sizeof(struct ct6_dsd));
-	ctx->fcp_cmnd = dma_pool_zalloc(ha->fcp_cmnd_dma_pool,
-	    GFP_ATOMIC, &ctx->fcp_cmnd_dma);
-	if (!ctx->fcp_cmnd) {
+	if (qla_get_buf(vha, sp->qpair, &sp->u.scmd.buf_dsc)) {
 		ql_log(ql_log_fatal, vha, 0x3011,
-		    "Failed to allocate fcp_cmnd for cmd=%p.\n", cmd);
+		    "Failed to allocate buf for fcp_cmnd for cmd=%p.\n", cmd);
 		goto queuing_error;
 	}
 
-	/* Initialize the DSD list and dma handle */
-	INIT_LIST_HEAD(&ctx->dsd_list);
-	ctx->dsd_use_cnt = 0;
+	sp->flags |= SRB_GOT_BUF;
+	ctx = &sp->u.scmd.ct6_ctx;
+	ctx->fcp_cmnd = sp->u.scmd.buf_dsc.buf;
+	ctx->fcp_cmnd_dma = sp->u.scmd.buf_dsc.buf_dma;
 
 	if (cmd->cmd_len > 16) {
 		additional_cdb_len = cmd->cmd_len - 16;
@@ -3145,7 +3135,6 @@ no_dsds:
 	cmd_pkt->fcp_cmnd_dseg_len = cpu_to_le16(ctx->fcp_cmnd_len);
 	put_unaligned_le64(ctx->fcp_cmnd_dma, &cmd_pkt->fcp_cmnd_dseg_address);
 
-	sp->flags |= SRB_FCP_CMND_DMA_VALID;
 	cmd_pkt->byte_count = cpu_to_le32((uint32_t)scsi_bufflen(cmd));
 	/* Set total data segment count. */
 	cmd_pkt->entry_count = (uint8_t)req_cnt;
@@ -3177,15 +3166,11 @@ no_dsds:
 	return QLA_SUCCESS;
 
 queuing_error_fcp_cmnd:
-	dma_pool_free(ha->fcp_cmnd_dma_pool, ctx->fcp_cmnd, ctx->fcp_cmnd_dma);
 queuing_error:
 	if (tot_dsds)
 		scsi_dma_unmap(cmd);
 
-	if (sp->u.scmd.ct6_ctx) {
-		mempool_free(sp->u.scmd.ct6_ctx, ha->ctx_mempool);
-		sp->u.scmd.ct6_ctx = NULL;
-	}
+	qla_put_buf(sp->qpair, &sp->u.scmd.buf_dsc);
 	qla_put_fw_resources(sp->qpair, &sp->iores);
 	spin_unlock_irqrestore(lock, flags);
 

drivers/scsi/qla2xxx/qla_gbl.h

@@ -1015,5 +1015,8 @@ int qla2xxx_enable_port(struct Scsi_Host *shost);
 
 uint64_t qla2x00_get_num_tgts(scsi_qla_host_t *vha);
 uint64_t qla2x00_count_set_bits(u32 num);
-
+int qla_create_buf_pool(struct scsi_qla_host *, struct qla_qpair *);
+void qla_free_buf_pool(struct qla_qpair *);
+int qla_get_buf(struct scsi_qla_host *, struct qla_qpair *, struct qla_buf_dsc *);
+void qla_put_buf(struct qla_qpair *, struct qla_buf_dsc *);
 #endif /* _QLA_GBL_H */

drivers/scsi/qla2xxx/qla_init.c

@@ -9442,6 +9442,13 @@ struct qla_qpair *qla2xxx_create_qpair(struct scsi_qla_host *vha, int qos,
 			goto fail_mempool;
 		}
 
+		if (qla_create_buf_pool(vha, qpair)) {
+			ql_log(ql_log_warn, vha, 0xd036,
+			    "Failed to initialize buf pool for qpair %d\n",
+			    qpair->id);
+			goto fail_bufpool;
+		}
+
 		/* Mark as online */
 		qpair->online = 1;
 
@@ -9457,7 +9464,10 @@ struct qla_qpair *qla2xxx_create_qpair(struct scsi_qla_host *vha, int qos,
 	}
 	return qpair;
 
+fail_bufpool:
+	mempool_destroy(qpair->srb_mempool);
 fail_mempool:
+	qla25xx_delete_req_que(vha, qpair->req);
 fail_req:
 	qla25xx_delete_rsp_que(vha, qpair->rsp);
 fail_rsp:
@@ -9483,6 +9493,8 @@ int qla2xxx_delete_qpair(struct scsi_qla_host *vha, struct qla_qpair *qpair)
 
 	qpair->delete_in_progress = 1;
 
+	qla_free_buf_pool(qpair);
+
 	ret = qla25xx_delete_req_que(vha, qpair->req);
 	if (ret != QLA_SUCCESS)
 		goto fail;

drivers/scsi/qla2xxx/qla_iocb.c

@@ -623,7 +623,7 @@ qla24xx_build_scsi_type_6_iocbs(srb_t *sp, struct cmd_type_6 *cmd_pkt,
 	}
 
 	cur_seg = scsi_sglist(cmd);
-	ctx = sp->u.scmd.ct6_ctx;
+	ctx = &sp->u.scmd.ct6_ctx;
 
 	while (tot_dsds) {
 		avail_dsds = (tot_dsds > QLA_DSDS_PER_IOCB) ?
@@ -3459,13 +3459,7 @@ sufficient_dsds:
 				goto queuing_error;
 		}
 
-		ctx = sp->u.scmd.ct6_ctx =
-		    mempool_alloc(ha->ctx_mempool, GFP_ATOMIC);
-		if (!ctx) {
-			ql_log(ql_log_fatal, vha, 0x3010,
-			    "Failed to allocate ctx for cmd=%p.\n", cmd);
-			goto queuing_error;
-		}
+		ctx = &sp->u.scmd.ct6_ctx;
 
 		memset(ctx, 0, sizeof(struct ct6_dsd));
 		ctx->fcp_cmnd = dma_pool_zalloc(ha->fcp_cmnd_dma_pool,

drivers/scsi/qla2xxx/qla_mid.c

@@ -1080,3 +1080,119 @@ void qla_update_host_map(struct scsi_qla_host *vha, port_id_t id)
 		qla_update_vp_map(vha, SET_AL_PA);
 	}
 }
+
+int qla_create_buf_pool(struct scsi_qla_host *vha, struct qla_qpair *qp)
+{
+	int sz;
+
+	qp->buf_pool.num_bufs = qp->req->length;
+
+	sz = BITS_TO_LONGS(qp->req->length);
+	qp->buf_pool.buf_map   = kcalloc(sz, sizeof(long), GFP_KERNEL);
+	if (!qp->buf_pool.buf_map) {
+		ql_log(ql_log_warn, vha, 0x0186,
+		    "Failed to allocate buf_map(%ld).\n", sz * sizeof(unsigned long));
+		return -ENOMEM;
+	}
+	sz = qp->req->length * sizeof(void *);
+	qp->buf_pool.buf_array = kcalloc(qp->req->length, sizeof(void *), GFP_KERNEL);
+	if (!qp->buf_pool.buf_array) {
+		ql_log(ql_log_warn, vha, 0x0186,
+		    "Failed to allocate buf_array(%d).\n", sz);
+		kfree(qp->buf_pool.buf_map);
+		return -ENOMEM;
+	}
+	sz = qp->req->length * sizeof(dma_addr_t);
+	qp->buf_pool.dma_array = kcalloc(qp->req->length, sizeof(dma_addr_t), GFP_KERNEL);
+	if (!qp->buf_pool.dma_array) {
+		ql_log(ql_log_warn, vha, 0x0186,
+		    "Failed to allocate dma_array(%d).\n", sz);
+		kfree(qp->buf_pool.buf_map);
+		kfree(qp->buf_pool.buf_array);
+		return -ENOMEM;
+	}
+	set_bit(0, qp->buf_pool.buf_map);
+	return 0;
+}
+
+void qla_free_buf_pool(struct qla_qpair *qp)
+{
+	int i;
+	struct qla_hw_data *ha = qp->vha->hw;
+
+	for (i = 0; i < qp->buf_pool.num_bufs; i++) {
+		if (qp->buf_pool.buf_array[i] && qp->buf_pool.dma_array[i])
+			dma_pool_free(ha->fcp_cmnd_dma_pool, qp->buf_pool.buf_array[i],
+			    qp->buf_pool.dma_array[i]);
+		qp->buf_pool.buf_array[i] = NULL;
+		qp->buf_pool.dma_array[i] = 0;
+	}
+
+	kfree(qp->buf_pool.dma_array);
+	kfree(qp->buf_pool.buf_array);
+	kfree(qp->buf_pool.buf_map);
+}
+
+/* it is assume qp->qp_lock is held at this point */
+int qla_get_buf(struct scsi_qla_host *vha, struct qla_qpair *qp, struct qla_buf_dsc *dsc)
+{
+	u16 tag, i = 0;
+	void *buf;
+	dma_addr_t buf_dma;
+	struct qla_hw_data *ha = vha->hw;
+
+	dsc->tag = TAG_FREED;
+again:
+	tag = find_first_zero_bit(qp->buf_pool.buf_map, qp->buf_pool.num_bufs);
+	if (tag >= qp->buf_pool.num_bufs) {
+		ql_dbg(ql_dbg_io, vha, 0x00e2,
+		    "qp(%d) ran out of buf resource.\n", qp->id);
+		return  -EIO;
+	}
+	if (tag == 0) {
+		set_bit(0, qp->buf_pool.buf_map);
+		i++;
+		if (i == 5) {
+			ql_dbg(ql_dbg_io, vha, 0x00e3,
+			    "qp(%d) unable to get tag.\n", qp->id);
+			return -EIO;
+		}
+		goto again;
+	}
+
+	if (!qp->buf_pool.buf_array[tag]) {
+		buf = dma_pool_zalloc(ha->fcp_cmnd_dma_pool, GFP_ATOMIC, &buf_dma);
+		if (!buf) {
+			ql_log(ql_log_fatal, vha, 0x13b1,
+			    "Failed to allocate buf.\n");
+			return -ENOMEM;
+		}
+
+		dsc->buf = qp->buf_pool.buf_array[tag] = buf;
+		dsc->buf_dma = qp->buf_pool.dma_array[tag] = buf_dma;
+	} else {
+		dsc->buf = qp->buf_pool.buf_array[tag];
+		dsc->buf_dma = qp->buf_pool.dma_array[tag];
+		memset(dsc->buf, 0, FCP_CMND_DMA_POOL_SIZE);
+	}
+
+	qp->buf_pool.num_active++;
+	if (qp->buf_pool.num_active > qp->buf_pool.max_used)
+		qp->buf_pool.max_used = qp->buf_pool.num_active;
+
+	dsc->tag = tag;
+	set_bit(tag, qp->buf_pool.buf_map);
+	return 0;
+}
+
+
+/* it is assume qp->qp_lock is held at this point */
+void qla_put_buf(struct qla_qpair *qp, struct qla_buf_dsc *dsc)
+{
+	if (dsc->tag == TAG_FREED)
+		return;
+
+	clear_bit(dsc->tag, qp->buf_pool.buf_map);
+	qp->buf_pool.num_active--;
+	dsc->tag = TAG_FREED;
+}

drivers/scsi/qla2xxx/qla_os.c

@@ -733,15 +733,17 @@ void qla2x00_sp_free_dma(srb_t *sp)
 	}
 
 	if (sp->flags & SRB_FCP_CMND_DMA_VALID) {
-		struct ct6_dsd *ctx1 = sp->u.scmd.ct6_ctx;
+		struct ct6_dsd *ctx1 = &sp->u.scmd.ct6_ctx;
 
 		dma_pool_free(ha->fcp_cmnd_dma_pool, ctx1->fcp_cmnd,
 		    ctx1->fcp_cmnd_dma);
 		list_splice(&ctx1->dsd_list, &ha->gbl_dsd_list);
 		ha->gbl_dsd_inuse -= ctx1->dsd_use_cnt;
 		ha->gbl_dsd_avail += ctx1->dsd_use_cnt;
-		mempool_free(ctx1, ha->ctx_mempool);
 	}
+
+	if (sp->flags & SRB_GOT_BUF)
+		qla_put_buf(sp->qpair, &sp->u.scmd.buf_dsc);
 }
 
 void qla2x00_sp_compl(srb_t *sp, int res)
@@ -817,14 +819,13 @@ void qla2xxx_qpair_sp_free_dma(srb_t *sp)
 	}
 
 	if (sp->flags & SRB_FCP_CMND_DMA_VALID) {
-		struct ct6_dsd *ctx1 = sp->u.scmd.ct6_ctx;
+		struct ct6_dsd *ctx1 = &sp->u.scmd.ct6_ctx;
 
 		dma_pool_free(ha->fcp_cmnd_dma_pool, ctx1->fcp_cmnd,
 		    ctx1->fcp_cmnd_dma);
 		list_splice(&ctx1->dsd_list, &ha->gbl_dsd_list);
 		ha->gbl_dsd_inuse -= ctx1->dsd_use_cnt;
 		ha->gbl_dsd_avail += ctx1->dsd_use_cnt;
-		mempool_free(ctx1, ha->ctx_mempool);
 		sp->flags &= ~SRB_FCP_CMND_DMA_VALID;
 	}
 
@@ -834,6 +835,9 @@ void qla2xxx_qpair_sp_free_dma(srb_t *sp)
 		dma_pool_free(ha->dl_dma_pool, ctx0, ctx0->crc_ctx_dma);
 		sp->flags &= ~SRB_CRC_CTX_DMA_VALID;
 	}
+
+	if (sp->flags & SRB_GOT_BUF)
+		qla_put_buf(sp->qpair, &sp->u.scmd.buf_dsc);
 }
 
 void qla2xxx_qpair_sp_compl(srb_t *sp, int res)