[PATCH v2 3/4] IB/srp: Fix residual handling

[Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>]

>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-HInyCGIudOg@public.gmane.org>
Reviewed-by: Sagi Grimberg <sagig-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Reviewed-by: David Dillow <dave-i1Mk8JYDVaaSihdK6806/g@public.gmane.org>
Cc: Sebastian Parschauer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 8bcdde8..6894822 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));
-- 
1.8.4.5

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