scsi: hisi_sas: relocate smp sg map

Currently we use DQ lock to protect delivery of DQ entry one by one.

To optimise to allow more than one slot to be built for a single DQ in
parallel, we need to remove the DQ lock when preparing slots, prior to
delivery.

To achieve this, we rearrange the slot build order to ensure that once
we allocate a slot for a task, we do cannot fail to deliver the task.

In this patch, we rearrange the slot building for SMP tasks to ensure
that sg mapping part (which can fail) happens before we allocate the
slot in the DQ.

Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 2 insertions, 31 deletions

diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
index 492c3beea3d5..cea5354c184f 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
@@ -986,38 +986,17 @@ static int prep_smp_v3_hw(struct hisi_hba *hisi_hba,
 	struct sas_task *task = slot->task;
 	struct hisi_sas_cmd_hdr *hdr = slot->cmd_hdr;
 	struct domain_device *device = task->dev;
-	struct device *dev = hisi_hba->dev;
 	struct hisi_sas_port *port = slot->port;
-	struct scatterlist *sg_req, *sg_resp;
+	struct scatterlist *sg_req;
 	struct hisi_sas_device *sas_dev = device->lldd_dev;
 	dma_addr_t req_dma_addr;
-	unsigned int req_len, resp_len;
-	int elem, rc;
+	unsigned int req_len;
 
-	/*
-	 * DMA-map SMP request, response buffers
-	 */
 	/* req */
 	sg_req = &task->smp_task.smp_req;
-	elem = dma_map_sg(dev, sg_req, 1, DMA_TO_DEVICE);
-	if (!elem)
-		return -ENOMEM;
 	req_len = sg_dma_len(sg_req);
 	req_dma_addr = sg_dma_address(sg_req);
 
-	/* resp */
-	sg_resp = &task->smp_task.smp_resp;
-	elem = dma_map_sg(dev, sg_resp, 1, DMA_FROM_DEVICE);
-	if (!elem) {
-		rc = -ENOMEM;
-		goto err_out_req;
-	}
-	resp_len = sg_dma_len(sg_resp);
-	if ((req_len & 0x3) || (resp_len & 0x3)) {
-		rc = -EINVAL;
-		goto err_out_resp;
-	}
-
 	/* create header */
 	/* dw0 */
 	hdr->dw0 = cpu_to_le32((port->id << CMD_HDR_PORT_OFF) |
@@ -1040,14 +1019,6 @@ static int prep_smp_v3_hw(struct hisi_hba *hisi_hba,
 	hdr->sts_buffer_addr = cpu_to_le64(hisi_sas_status_buf_addr_dma(slot));
 
 	return 0;
-
-err_out_resp:
-	dma_unmap_sg(dev, &slot->task->smp_task.smp_resp, 1,
-		     DMA_FROM_DEVICE);
-err_out_req:
-	dma_unmap_sg(dev, &slot->task->smp_task.smp_req, 1,
-		     DMA_TO_DEVICE);
-	return rc;
 }
 
 static int prep_ata_v3_hw(struct hisi_hba *hisi_hba,