Re: [PATCH] ntb_transport: fix qp count bug

From: Logan Gunthorpe
Date: Fri Dec 08 2017 - 19:02:20 EST


Sorry, ignore this. I sent an old patch.

Logan

On 08/12/17 05:01 PM, Logan Gunthorpe wrote:
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>
Cc: Jon Mason <jdmason@xxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: Allen Hubbe <Allen.Hubbe@xxxxxxx>
---
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 02ca45fdd892..0a778d2cab94 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -1128,8 +1128,8 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev)
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;