From 8e8496e0e9564b66165f5219a4e8ed20b0d3fc6b Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Mon, 5 Jun 2017 14:00:53 -0600 Subject: [PATCH] ntb_transport: fix bug calculating num_qps_mw A divide by zero error occurs if qp_count is less than mw_count because num_qps_mw is calculated to be zero. The calculation appears to be incorrect. The requirement is for num_qps_mw to be set to qp_count / mw_count with any remainder divided among the earlier mws. For example, if mw_count is 5 and qp_count is 12 then mws 0 and 1 will have 3 qps per window and mws 2 through 4 will have 2 qps per window. Thus, when mw_num < qp_count % mw_count, num_qps_mw is 1 higher than when mw_num >= qp_count. Signed-off-by: Logan Gunthorpe Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers") Acked-by: Allen Hubbe Signed-off-by: Jon Mason --- drivers/ntb/ntb_transport.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c index 0a778d2cab94..5b6b00ea6ed9 100644 --- a/drivers/ntb/ntb_transport.c +++ b/drivers/ntb/ntb_transport.c @@ -623,7 +623,7 @@ static int ntb_transport_setup_qp_mw(struct ntb_transport_ctx *nt, if (!mw->virt_addr) return -ENOMEM; - if (qp_count % mw_count && mw_num + 1 < qp_count / mw_count) + if (mw_num < qp_count % mw_count) num_qps_mw = qp_count / mw_count + 1; else num_qps_mw = qp_count / mw_count; @@ -1000,7 +1000,7 @@ static int ntb_transport_init_queue(struct ntb_transport_ctx *nt, qp->event_handler = NULL; ntb_qp_link_down_reset(qp); - if (qp_count % mw_count && mw_num + 1 < qp_count / mw_count) + if (mw_num < qp_count % mw_count) num_qps_mw = qp_count / mw_count + 1; else num_qps_mw = qp_count / mw_count;