From: Christoph Hellwig <hch@lst.de>
Date: Wed, 2 Mar 2016 17:07:12 +0000 (+0100)
Subject: nvme: fix max_segments integer truncation
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=45686b6198bd824f083ff5293f191d78db9d708a;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

nvme: fix max_segments integer truncation

The block layer uses an unsigned short for max_segments.  The way we
calculate the value for NVMe tends to generate very large 32-bit values,
which after integer truncation may lead to a zero value instead of
the desired outcome.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Jeff Lien <Jeff.Lien@hgst.com>
Tested-by: Jeff Lien <Jeff.Lien@hgst.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index cfee6ac399a3..03c46412fff4 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -844,9 +844,11 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
 		struct request_queue *q)
 {
 	if (ctrl->max_hw_sectors) {
+		u32 max_segments =
+			(ctrl->max_hw_sectors / (ctrl->page_size >> 9)) + 1;
+
 		blk_queue_max_hw_sectors(q, ctrl->max_hw_sectors);
-		blk_queue_max_segments(q,
-			(ctrl->max_hw_sectors / (ctrl->page_size >> 9)) + 1);
+		blk_queue_max_segments(q, min_t(u32, max_segments, USHRT_MAX));
 	}
 	if (ctrl->stripe_size)
 		blk_queue_chunk_sectors(q, ctrl->stripe_size >> 9);