[PATCH] IB/iser: Handle lack of memory management extentions correctly

[Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

max_fast_reg_page_list_len is only valid when the
memory management extentions are signaled by the underlying
driver.

Fix by adjusting iser_calc_scsi_params() to use
ISCSI_ISER_MAX_SG_TABLESIZE when the extentions are not indicated.

Reported-by: Thomas Rosenstein <thomas.rosenstein-+32LHaKS/h5VtLMLtJdGzA@public.gmane.org>
Fixes: Commit df749cdc45d9 ("IB/iser: Support up to 8MB data transfer in a single command")
Reviewed-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/infiniband/ulp/iser/iser_verbs.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c
index c538a38..26a004e 100644
--- a/drivers/infiniband/ulp/iser/iser_verbs.c
+++ b/drivers/infiniband/ulp/iser/iser_verbs.c
@@ -708,8 +708,14 @@ static void iser_connect_error(struct rdma_cm_id *cma_id)
 	unsigned short sg_tablesize, sup_sg_tablesize;
 
 	sg_tablesize = DIV_ROUND_UP(max_sectors * 512, SIZE_4K);
-	sup_sg_tablesize = min_t(unsigned, ISCSI_ISER_MAX_SG_TABLESIZE,
-				 device->ib_device->attrs.max_fast_reg_page_list_len);
+	if (device->ib_device->attrs.device_cap_flags &
+			IB_DEVICE_MEM_MGT_EXTENSIONS)
+		sup_sg_tablesize =
+			min_t(
+			 uint, ISCSI_ISER_MAX_SG_TABLESIZE,
+			 device->ib_device->attrs.max_fast_reg_page_list_len);
+	else
+		sup_sg_tablesize = ISCSI_ISER_MAX_SG_TABLESIZE;
 
 	iser_conn->scsi_sg_tablesize = min(sg_tablesize, sup_sg_tablesize);
 }

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