[PATCH 4.4 50/53] ntb_transport: fix qp count bug

[Greg Kroah-Hartman]

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

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

From: Logan Gunthorpe <logang@xxxxxxxxxxxx>

commit cb827ee6ccc3e480f0d9c0e8e53eef55be5b0414 upstream.

In cases where there are more mw's than spads/2-2, the mw count gets
reduced to match the limitation. ntb_transport also tries to ensure that
there are fewer qps than mws but uses the full mw count instead of
the reduced one. When this happens, the math in
'ntb_transport_setup_qp_mw' will get confused and result in a kernel
paging request bug.

This patch fixes the bug by reducing qp_count to the reduced mw count
instead of the full mw count.

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Acked-by: Allen Hubbe <Allen.Hubbe@xxxxxxxx>
Signed-off-by: Jon Mason <jdmason@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/ntb/ntb_transport.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -1065,8 +1065,8 @@ static int ntb_transport_probe(struct nt
 	qp_count = ilog2(qp_bitmap);
 	if (max_num_clients && max_num_clients < qp_count)
 		qp_count = max_num_clients;
-	else if (mw_count < qp_count)
-		qp_count = mw_count;
+	else if (nt->mw_count < qp_count)
+		qp_count = nt->mw_count;
 
 	qp_bitmap &= BIT_ULL(qp_count) - 1;