scsi: lpfc: Fix too many sg segments spamming in kernel log

This issue is specific to SLI-3 adapters, specifically when DIF is used.

Once seen, this message floods the logs:
9064 BLKGRD: lpfc_scsi_prep_dma_buf_s3: Too many sg segments from
  dma_map_sg

The driver, upon detecting an error such as too many elements in an sglist,
misrepresents the error by treating it as a temporary resource issue by
returning MLQUEUE_HOST_BUSY.  In these cases, no retry will fix it and it
should have been a hard error. The repeated retry was causing the spamming
of the log.

As for the initial reason of why an I/O encountered this issue at all is
not clear as parameters set by the driver should have avoided this.  The
dm multipath maintainer has been notified of the issue.

Fix by changing the return code for the dma mapping routines to indicate
cases that are not retryable and return DID_ERROR on those cases.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 60 insertions, 19 deletions

diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index 720a98266986..8ae24500806e 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -918,9 +918,10 @@ lpfc_scsi_prep_dma_buf_s3(struct lpfc_hba *phba, struct lpfc_io_buf *lpfc_cmd)
 			       "dma_map_sg.  Config %d, seg_cnt %d\n",
 			       __func__, phba->cfg_sg_seg_cnt,
 			       lpfc_cmd->seg_cnt);
+			WARN_ON_ONCE(lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt);
 			lpfc_cmd->seg_cnt = 0;
 			scsi_dma_unmap(scsi_cmnd);
-			return 1;
+			return 2;
 		}
 
 		/*
@@ -2430,7 +2431,10 @@ lpfc_bg_scsi_adjust_dl(struct lpfc_hba *phba,
  *
  * This is the protection/DIF aware version of
  * lpfc_scsi_prep_dma_buf(). It may be a good idea to combine the
- * two functions eventually, but for now, it's here
+ * two functions eventually, but for now, it's here.
+ * RETURNS 0 - SUCCESS,
+ *         1 - Failed DMA map, retry.
+ *         2 - Invalid scsi cmd or prot-type. Do not rety.
  **/
 static int
 lpfc_bg_scsi_prep_dma_buf_s3(struct lpfc_hba *phba,
@@ -2444,6 +2448,7 @@ lpfc_bg_scsi_prep_dma_buf_s3(struct lpfc_hba *phba,
 	int datasegcnt, protsegcnt, datadir = scsi_cmnd->sc_data_direction;
 	int prot_group_type = 0;
 	int fcpdl;
+	int ret = 1;
 	struct lpfc_vport *vport = phba->pport;
 
 	/*
@@ -2467,8 +2472,11 @@ lpfc_bg_scsi_prep_dma_buf_s3(struct lpfc_hba *phba,
 		lpfc_cmd->seg_cnt = datasegcnt;
 
 		/* First check if data segment count from SCSI Layer is good */
-		if (lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt)
+		if (lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt) {
+			WARN_ON_ONCE(lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt);
+			ret = 2;
 			goto err;
+		}
 
 		prot_group_type = lpfc_prot_group_type(phba, scsi_cmnd);
 
@@ -2476,14 +2484,18 @@ lpfc_bg_scsi_prep_dma_buf_s3(struct lpfc_hba *phba,
 		case LPFC_PG_TYPE_NO_DIF:
 
 			/* Here we need to add a PDE5 and PDE6 to the count */
-			if ((lpfc_cmd->seg_cnt + 2) > phba->cfg_total_seg_cnt)
+			if ((lpfc_cmd->seg_cnt + 2) > phba->cfg_total_seg_cnt) {
+				ret = 2;
 				goto err;
+			}
 
 			num_bde = lpfc_bg_setup_bpl(phba, scsi_cmnd, bpl,
 					datasegcnt);
 			/* we should have 2 or more entries in buffer list */
-			if (num_bde < 2)
+			if (num_bde < 2) {
+				ret = 2;
 				goto err;
+			}
 			break;
 
 		case LPFC_PG_TYPE_DIF_BUF:
@@ -2507,15 +2519,19 @@ lpfc_bg_scsi_prep_dma_buf_s3(struct lpfc_hba *phba,
 			 * protection data segment.
 			 */
 			if ((lpfc_cmd->prot_seg_cnt * 4) >
-			    (phba->cfg_total_seg_cnt - 2))
+			    (phba->cfg_total_seg_cnt - 2)) {
+				ret = 2;
 				goto err;
+			}
 
 			num_bde = lpfc_bg_setup_bpl_prot(phba, scsi_cmnd, bpl,
 					datasegcnt, protsegcnt);
 			/* we should have 3 or more entries in buffer list */
 			if ((num_bde < 3) ||
-			    (num_bde > phba->cfg_total_seg_cnt))
+			    (num_bde > phba->cfg_total_seg_cnt)) {
+				ret = 2;
 				goto err;
+			}
 			break;
 
 		case LPFC_PG_TYPE_INVALID:
@@ -2526,7 +2542,7 @@ lpfc_bg_scsi_prep_dma_buf_s3(struct lpfc_hba *phba,
 			lpfc_printf_log(phba, KERN_ERR, LOG_FCP,
 					"9022 Unexpected protection group %i\n",
 					prot_group_type);
-			return 1;
+			return 2;
 		}
 	}
 
@@ -2576,7 +2592,7 @@ err:
 
 	lpfc_cmd->seg_cnt = 0;
 	lpfc_cmd->prot_seg_cnt = 0;
-	return 1;
+	return ret;
 }
 
 /*
@@ -2962,7 +2978,8 @@ out:
  * field of @lpfc_cmd for device with SLI-4 interface spec.
  *
  * Return codes:
- *	1 - Error
+ *	2 - Error - Do not retry
+ *	1 - Error - Retry
  *	0 - Success
  **/
 static int
@@ -3012,9 +3029,10 @@ lpfc_scsi_prep_dma_buf_s4(struct lpfc_hba *phba, struct lpfc_io_buf *lpfc_cmd)
 				"dma_map_sg.  Config %d, seg_cnt %d\n",
 				__func__, phba->cfg_sg_seg_cnt,
 			       lpfc_cmd->seg_cnt);
+			WARN_ON_ONCE(lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt);
 			lpfc_cmd->seg_cnt = 0;
 			scsi_dma_unmap(scsi_cmnd);
-			return 1;
+			return 2;
 		}
 
 		/*
@@ -3110,6 +3128,10 @@ lpfc_scsi_prep_dma_buf_s4(struct lpfc_hba *phba, struct lpfc_io_buf *lpfc_cmd)
  * This is the protection/DIF aware version of
  * lpfc_scsi_prep_dma_buf(). It may be a good idea to combine the
  * two functions eventually, but for now, it's here
+ * Return codes:
+ *	2 - Error - Do not retry
+ *	1 - Error - Retry
+ *	0 - Success
  **/
 static int
 lpfc_bg_scsi_prep_dma_buf_s4(struct lpfc_hba *phba,
@@ -3123,6 +3145,7 @@ lpfc_bg_scsi_prep_dma_buf_s4(struct lpfc_hba *phba,
 	int datasegcnt, protsegcnt, datadir = scsi_cmnd->sc_data_direction;
 	int prot_group_type = 0;
 	int fcpdl;
+	int ret = 1;
 	struct lpfc_vport *vport = phba->pport;
 
 	/*
@@ -3152,23 +3175,30 @@ lpfc_bg_scsi_prep_dma_buf_s4(struct lpfc_hba *phba,
 		lpfc_cmd->seg_cnt = datasegcnt;
 
 		/* First check if data segment count from SCSI Layer is good */
-		if (lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt)
+		if (lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt) {
+			WARN_ON_ONCE(lpfc_cmd->seg_cnt > phba->cfg_sg_seg_cnt);
+			ret = 2;
 			goto err;
+		}
 
 		prot_group_type = lpfc_prot_group_type(phba, scsi_cmnd);
 
 		switch (prot_group_type) {
 		case LPFC_PG_TYPE_NO_DIF:
 			/* Here we need to add a DISEED to the count */
-			if ((lpfc_cmd->seg_cnt + 1) > phba->cfg_total_seg_cnt)
+			if ((lpfc_cmd->seg_cnt + 1) > phba->cfg_total_seg_cnt) {
+				ret = 2;
 				goto err;
+			}
 
 			num_sge = lpfc_bg_setup_sgl(phba, scsi_cmnd, sgl,
 					datasegcnt);
 
 			/* we should have 2 or more entries in buffer list */
-			if (num_sge < 2)
+			if (num_sge < 2) {
+				ret = 2;
 				goto err;
+			}
 			break;
 
 		case LPFC_PG_TYPE_DIF_BUF:
@@ -3191,16 +3221,20 @@ lpfc_bg_scsi_prep_dma_buf_s4(struct lpfc_hba *phba,
 			 * protection data segment.
 			 */
 			if ((lpfc_cmd->prot_seg_cnt * 3) >
-			    (phba->cfg_total_seg_cnt - 2))
+			    (phba->cfg_total_seg_cnt - 2)) {
+				ret = 2;
 				goto err;
+			}
 
 			num_sge = lpfc_bg_setup_sgl_prot(phba, scsi_cmnd, sgl,
 					datasegcnt, protsegcnt);
 
 			/* we should have 3 or more entries in buffer list */
 			if ((num_sge < 3) ||
-			    (num_sge > phba->cfg_total_seg_cnt))
+			    (num_sge > phba->cfg_total_seg_cnt)) {
+				ret = 2;
 				goto err;
+			}
 			break;
 
 		case LPFC_PG_TYPE_INVALID:
@@ -3211,7 +3245,7 @@ lpfc_bg_scsi_prep_dma_buf_s4(struct lpfc_hba *phba,
 			lpfc_printf_log(phba, KERN_ERR, LOG_FCP,
 					"9083 Unexpected protection group %i\n",
 					prot_group_type);
-			return 1;
+			return 2;
 		}
 	}
 
@@ -3273,7 +3307,7 @@ err:
 
 	lpfc_cmd->seg_cnt = 0;
 	lpfc_cmd->prot_seg_cnt = 0;
-	return 1;
+	return ret;
 }
 
 /**
@@ -4454,8 +4488,12 @@ lpfc_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *cmnd)
 		err = lpfc_scsi_prep_dma_buf(phba, lpfc_cmd);
 	}
 
-	if (err)
+	if (err == 2) {
+		cmnd->result = DID_ERROR << 16;
+		goto out_fail_command_release_buf;
+	} else if (err) {
 		goto out_host_busy_free_buf;
+	}
 
 	lpfc_scsi_prep_cmnd(vport, lpfc_cmd, ndlp);
 
@@ -4526,6 +4564,9 @@ lpfc_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *cmnd)
  out_tgt_busy:
 	return SCSI_MLQUEUE_TARGET_BUSY;
 
+ out_fail_command_release_buf:
+	lpfc_release_scsi_buf(phba, lpfc_cmd);
+
  out_fail_command:
 	cmnd->scsi_done(cmnd);
 	return 0;