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From:   Christian Schoenebeck <linux_oss@crudebyte.com>
Date:   Tue, 12 Jul 2022 16:31:09 +0200
Subject: [PATCH v5 01/11] 9p/trans_virtio: separate allocation of scatter
 gather list
To:     v9fs-developer@lists.sourceforge.net
Cc:     linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Dominique Martinet <asmadeus@codewreck.org>,
        Eric Van Hensbergen <ericvh@gmail.com>,
        Latchesar Ionkov <lucho@ionkov.net>,
        Nikolay Kichukov <nikolay@oldum.net>
Precedence: bulk

The scatter gather list in struct virtio_chan currently
resides as compile-time constant size array directly within the
contiguous struct virtio_chan's memory space.

Separate memory space and allocation of the scatter gather list
from memory space and allocation of struct virtio_chan.

Signed-off-by: Christian Schoenebeck <linux_oss@crudebyte.com>
---
 net/9p/trans_virtio.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index b24a4fb0f0a2..2693e618080c 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -77,7 +77,7 @@ struct virtio_chan {
 	 */
 	unsigned long p9_max_pages;
 	/* Scatterlist: can be too big for stack. */
-	struct scatterlist sg[VIRTQUEUE_NUM];
+	struct scatterlist *sg;
 	/**
 	 * @tag: name to identify a mount null terminated
 	 */
@@ -574,6 +574,14 @@ static int p9_virtio_probe(struct virtio_device *vdev)
 		goto fail;
 	}
 
+	chan->sg = kmalloc_array(VIRTQUEUE_NUM,
+				 sizeof(struct scatterlist), GFP_KERNEL);
+	if (!chan->sg) {
+		pr_err("Failed to allocate virtio 9P channel\n");
+		err = -ENOMEM;
+		goto out_free_chan_shallow;
+	}
+
 	chan->vdev = vdev;
 
 	/* We expect one virtqueue, for requests. */
@@ -635,6 +643,8 @@ static int p9_virtio_probe(struct virtio_device *vdev)
 out_free_vq:
 	vdev->config->del_vqs(vdev);
 out_free_chan:
+	kfree(chan->sg);
+out_free_chan_shallow:
 	kfree(chan);
 fail:
 	return err;
@@ -728,6 +738,7 @@ static void p9_virtio_remove(struct virtio_device *vdev)
 	kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
 	kfree(chan->tag);
 	kfree(chan->vc_wq);
+	kfree(chan->sg);
 	kfree(chan);
 
 }
-- 
2.30.2