linux-kernel - [PATCH] virtio-ring: fix DMA metadata flags

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Message-ID: <20211026133100.17541-1-vincent.whitchurch@axis.com>
Date:   Tue, 26 Oct 2021 15:31:00 +0200
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>
CC:     <kernel@...s.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        <virtualization@...ts.linux-foundation.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] virtio-ring: fix DMA metadata flags

The flags are currently overwritten, leading to the wrong direction
being passed to the DMA unmap functions.

Fixes: 72b5e8958738aaa4 ("virtio-ring: store DMA metadata in desc_extra for split virtqueue")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---
 drivers/virtio/virtio_ring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index dd95dfd85e98..3035bb6f5458 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -576,7 +576,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 	/* Last one doesn't continue. */
 	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
 	if (!indirect && vq->use_dma_api)
-		vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags =
+		vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &=
 			~VRING_DESC_F_NEXT;
 
 	if (indirect) {
-- 
2.28.0