IB/srp: Fix residual handling

From Documentation/scsi/scsi_mid_low_api.txt: "resid - an LLD should
set this signed integer to the requested transfer length (i.e.
'request_bufflen') less the number of bytes that are actually
transferred."  This means that resid > 0 in case of an underrun and
also that resid < 0 in case of an overrun.  Modify the SRP initiator
code such that it matches this requirement.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: David Dillow <dave@thedillows.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 767000811cf9..7f5ee7fc02a6 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -1644,10 +1644,14 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
                                      SCSI_SENSE_BUFFERSIZE));
                 }
 
-                if (rsp->flags & (SRP_RSP_FLAG_DOOVER | SRP_RSP_FLAG_DOUNDER))
-                        scsi_set_resid(scmnd, be32_to_cpu(rsp->data_out_res_cnt));
-                else if (rsp->flags & (SRP_RSP_FLAG_DIOVER | SRP_RSP_FLAG_DIUNDER))
+                if (unlikely(rsp->flags & SRP_RSP_FLAG_DIUNDER))
                         scsi_set_resid(scmnd, be32_to_cpu(rsp->data_in_res_cnt));
+                else if (unlikely(rsp->flags & SRP_RSP_FLAG_DIOVER))
+                        scsi_set_resid(scmnd, -be32_to_cpu(rsp->data_in_res_cnt));
+                else if (unlikely(rsp->flags & SRP_RSP_FLAG_DOUNDER))
+                        scsi_set_resid(scmnd, be32_to_cpu(rsp->data_out_res_cnt));
+                else if (unlikely(rsp->flags & SRP_RSP_FLAG_DOOVER))
+                        scsi_set_resid(scmnd, -be32_to_cpu(rsp->data_out_res_cnt));
 
                 srp_free_req(target, req, scmnd,
                              be32_to_cpu(rsp->req_lim_delta));