Patch "ntb_transport: fix qp count bug" has been added to the 4.9-stable tree

Patch "ntb_transport: fix qp count bug" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ntb_transport: fix qp count bug

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ntb_transport-fix-qp-count-bug.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From cb827ee6ccc3e480f0d9c0e8e53eef55be5b0414 Mon Sep 17 00:00:00 2001
From: Logan Gunthorpe <logang@deltatee.com>
Date: Mon, 5 Jun 2017 14:00:52 -0600
Subject: ntb_transport: fix qp count bug

From: Logan Gunthorpe <logang@deltatee.com>

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@deltatee.com>
Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -1125,8 +1125,8 @@ 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;
 


Patches currently in stable-queue which might be from logang@deltatee.com are

queue-4.9/ntb-ntb_test-fix-bug-printing-ntb_perf-results.patch
queue-4.9/ntb_transport-fix-bug-calculating-num_qps_mw.patch
queue-4.9/ntb-ntb_test-ensure-the-link-is-up-before-trying-to-configure-the-mws.patch
queue-4.9/ntb_transport-fix-qp-count-bug.patch