[PATCH 3.16.y-ckt 62/71] iser-target: Fix variable-length response error completion

[Luis Henriques]

3.16.7-ckt14 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sagi Grimberg <sagig@xxxxxxxxxxxx>

commit 9253e667ab50fd4611a60e1cdd6a6e05a1d91cf1 upstream.

Since commit "2426bd456a6 target: Report correct response ..."
we might get a command with data_size that does not fit to
the number of allocated data sg elements. Given that we rely on
cmd t_data_nents which might be different than the data_size,
we sometimes receive local length error completion. The correct
approach would be to take the command data_size into account when
constructing the ib sg_list.

Signed-off-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Signed-off-by: Jenny Falkovich <jennyf@xxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 drivers/infiniband/ulp/isert/ib_isert.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 31939ba1d238..8a02eb55bc67 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -2487,7 +2487,6 @@ isert_build_rdma_wr(struct isert_conn *isert_conn, struct isert_cmd *isert_cmd,
 	page_off = offset % PAGE_SIZE;
 
 	send_wr->sg_list = ib_sge;
-	send_wr->num_sge = sg_nents;
 	send_wr->wr_id = (unsigned long)&isert_cmd->tx_desc;
 	/*
 	 * Perform mapping of TCM scatterlist memory ib_sge dma_addr.
@@ -2506,14 +2505,17 @@ isert_build_rdma_wr(struct isert_conn *isert_conn, struct isert_cmd *isert_cmd,
 			 ib_sge->addr, ib_sge->length, ib_sge->lkey);
 		page_off = 0;
 		data_left -= ib_sge->length;
+		if (!data_left)
+			break;
 		ib_sge++;
 		pr_debug("Incrementing ib_sge pointer to %p\n", ib_sge);
 	}
 
+	send_wr->num_sge = ++i;
 	pr_debug("Set outgoing sg_list: %p num_sg: %u from TCM SGLs\n",
 		 send_wr->sg_list, send_wr->num_sge);
 
-	return sg_nents;
+	return send_wr->num_sge;
 }
 
 static int
--
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