IB/{hfi1, qib}: Fix WC.byte_len calculation for UD_SEND_WITH_IMM

This change “IB/{hfi1, qib}: Fix WC.byte_len calculation for UD_SEND_WITH_IMM” in Linux kernel is authored by Brian Welty <brian.welty [at] intel.com> on Thu Jan 17 12:41:32 2019 -0800.

IB/{hfi1, qib}: Fix WC.byte_len calculation for UD_SEND_WITH_IMM

The work completion length for a receiving a UD send with immediate is
short by 4 bytes causing application using this opcode to fail.

The UD receive logic incorrectly subtracts 4 bytes for immediate
value. These bytes are already included in header length and are used to
calculate header/payload split, so the result is these 4 bytes are
subtracted twice, once when the header length subtracted from the overall
length and once again in the UD opcode specific path.

Remove the extra subtraction when handling the opcode.

Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Brian Welty <brian.welty@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit 904bba2.

There are 2 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/infiniband/hw/hfi1/ud.c    | 1 -
 drivers/infiniband/hw/qib/qib_ud.c | 1 -
 2 files changed, 2 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/ud.c b/drivers/infiniband/hw/hfi1/ud.c
index 88242fe..bf96067 100644
--- a/drivers/infiniband/hw/hfi1/ud.c
+++ b/drivers/infiniband/hw/hfi1/ud.c
@@ -987,7 +987,6 @@ void hfi1_ud_rcv(struct hfi1_packet *packet)
 	    opcode == IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE) {
 		wc.ex.imm_data = packet->ohdr->u.ud.imm_data;
 		wc.wc_flags = IB_WC_WITH_IMM;
-		tlen -= sizeof(u32);
 	} else if (opcode == IB_OPCODE_UD_SEND_ONLY) {
 		wc.ex.imm_data = 0;
 		wc.wc_flags = 0;
diff --git a/drivers/infiniband/hw/qib/qib_ud.c b/drivers/infiniband/hw/qib/qib_ud.c
index 868da0e..445ea19 100644
--- a/drivers/infiniband/hw/qib/qib_ud.c
+++ b/drivers/infiniband/hw/qib/qib_ud.c
@@ -512,7 +512,6 @@ void qib_ud_rcv(struct qib_ibport *ibp, struct ib_header *hdr,
 	    opcode == IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE) {
 		wc.ex.imm_data = ohdr->u.ud.imm_data;
 		wc.wc_flags = IB_WC_WITH_IMM;
-		tlen -= sizeof(u32);
 	} else if (opcode == IB_OPCODE_UD_SEND_ONLY) {
 		wc.ex.imm_data = 0;
 		wc.wc_flags = 0;

The commit for this change in Linux stable tree is 904bba2 (patch).

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