[SCSI] qla2xxx: Correct residual-count handling discrepancies during UNDERRUN handling.

For recent ISPs, software during CS_UNDERRUN handling must
determine if the two residuals, firmware-calculated and FCP_RSP,
are different to recognize if a frame has been dropped.  Update
the driver to catch this condition, and clear the
SS_RESIDUAL_UNDER and lscsi_status bits.  This logic is
consistent with what earlier firmwares did by explicitly
cracking open the FCP_RSP statuses and clearing
SS_RESIDUAL_UNDER.

Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
index c4768c4f3990..1104bd2eed40 100644
--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -1012,8 +1012,14 @@ qla2x00_status_entry(scsi_qla_host_t *ha, void *pkt)
         case CS_DATA_UNDERRUN:
                 resid = resid_len;
                 /* Use F/W calculated residual length. */
-                if (IS_FWI2_CAPABLE(ha))
+                if (IS_FWI2_CAPABLE(ha)) {
+                        if (scsi_status & SS_RESIDUAL_UNDER &&
+                            resid != fw_resid_len) {
+                                scsi_status &= ~SS_RESIDUAL_UNDER;
+                                lscsi_status = 0;
+                        }
                         resid = fw_resid_len;
+                }
 
                 if (scsi_status & SS_RESIDUAL_UNDER) {
                         scsi_set_resid(cp, resid);