Re: [PATCH] scsi: lpfc: use unsigned type for num_sge

[Dick Kennedy]

The change is good, however, I  don't think this was really the problem. 

We would  like to know if this patch really solved an issue they observed.

 A good data point to know is what adapter they're using.
 If that adapter supports hybrid sgl (i.e. phba->cfg_xpsgl), then we
 would have set the max sg_tablesize = LPFC_MAX_SG_TABLESIZE = 0xffff.

 But even then, this patch implies that dma_map_sg() returned a crazy
 huge amount with the MSB set.

On Wed, Dec 20, 2023 at 8:29 AM Daniel Wagner <dwagner@xxxxxxx> wrote:

From: Hannes Reinecke <hare@xxxxxxx>

LUNs going into “failed ready running” state observed on >1T and on
even numbers of size (2T, 4T, 6T, 8T and 10T). The issue occurs when
DIF is enabled at the host.

The kernel logs:

  Cannot setup S/G List for HBAIO segs 1/1 SGL 512 SCSI 256: 3 0

The host lpfc driver is failing to setup scatter/gather list
(protection data) for the IO's.

The return type lpfc_bg_setup_sgl()/lpfc_bg_setup_sgl_prot() causes
the compiler to remove the most significant bit. Use an unsigned type
instead.

Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
[dwagner: added commit message]
Signed-off-by: Daniel Wagner <dwagner@xxxxxxx>
---
 drivers/scsi/lpfc/lpfc_scsi.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index d26941b131fd..bf879d81846b 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -1918,7 +1918,7 @@ lpfc_bg_setup_bpl_prot(struct lpfc_hba *phba, struct scsi_cmnd *sc,
  *
  * Returns the number of SGEs added to the SGL.
  **/
-static int
+static uint32_t
 lpfc_bg_setup_sgl(struct lpfc_hba *phba, struct scsi_cmnd *sc,
                struct sli4_sge *sgl, int datasegcnt,
                struct lpfc_io_buf *lpfc_cmd)
@@ -1926,8 +1926,8 @@ lpfc_bg_setup_sgl(struct lpfc_hba *phba, struct scsi_cmnd *sc,
        struct scatterlist *sgde = NULL; /* s/g data entry */
        struct sli4_sge_diseed *diseed = NULL;
        dma_addr_t physaddr;
-       int i = 0, num_sge = 0, status;
-       uint32_t reftag;
+       int i = 0, status;
+       uint32_t reftag, num_sge = 0;
        uint8_t txop, rxop;
 #ifdef CONFIG_SCSI_LPFC_DEBUG_FS
        uint32_t rc;
@@ -2099,7 +2099,7 @@ lpfc_bg_setup_sgl(struct lpfc_hba *phba, struct scsi_cmnd *sc,
  *
  * Returns the number of SGEs added to the SGL.
  **/
-static int
+static uint32_t
 lpfc_bg_setup_sgl_prot(struct lpfc_hba *phba, struct scsi_cmnd *sc,
                struct sli4_sge *sgl, int datacnt, int protcnt,
                struct lpfc_io_buf *lpfc_cmd)
@@ -2123,8 +2123,8 @@ lpfc_bg_setup_sgl_prot(struct lpfc_hba *phba, struct scsi_cmnd *sc,
        uint32_t rc;
 #endif
        uint32_t checking = 1;
-       uint32_t dma_offset = 0;
-       int num_sge = 0, j = 2;
+       uint32_t dma_offset = 0, num_sge = 0;
+       int j = 2;
        struct sli4_hybrid_sgl *sgl_xtra = NULL;

        sgpe = scsi_prot_sglist(sc);
--
2.43.0

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