4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Logan Gunthorpe <logang@xxxxxxxxxxxx>
commit 8e8496e0e9564b66165f5219a4e8ed20b0d3fc6b upstream.
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 <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
@@ -599,7 +599,7 @@ static int ntb_transport_setup_qp_mw(str
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;
@@ -947,7 +947,7 @@ static int ntb_transport_init_queue(stru
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;