This is a note to let you know that I've just added the patch titled
virtio: Honour 'may_reduce_num' in vring_create_virtqueue
to the 5.0-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:
virtio-honour-may_reduce_num-in-vring_create_virtqueue.patch
and it can be found in the queue-5.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cf94db21905333e610e479688add629397a4b384 Mon Sep 17 00:00:00 2001
From: Cornelia Huck <cohuck@xxxxxxxxxx>
Date: Mon, 8 Apr 2019 14:33:22 +0200
Subject: virtio: Honour 'may_reduce_num' in vring_create_virtqueue
From: Cornelia Huck <cohuck@xxxxxxxxxx>
commit cf94db21905333e610e479688add629397a4b384 upstream.
vring_create_virtqueue() allows the caller to specify via the
may_reduce_num parameter whether the vring code is allowed to
allocate a smaller ring than specified.
However, the split ring allocation code tries to allocate a
smaller ring on allocation failure regardless of what the
caller specified. This may cause trouble for e.g. virtio-pci
in legacy mode, which does not support ring resizing. (The
packed ring code does not resize in any case.)
Let's fix this by bailing out immediately in the split ring code
if the requested size cannot be allocated and may_reduce_num has
not been specified.
While at it, fix a typo in the usage instructions.
Fixes: 2a2d1382fe9d ("virtio: Add improved queue allocation API")
Cc: stable@xxxxxxxxxxxxxxx # v4.6+
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
Reviewed-by: Jens Freimann <jfreimann@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 2 ++
include/linux/virtio_ring.h | 2 +-
2 files changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -871,6 +871,8 @@ static struct virtqueue *vring_create_vi
GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
if (queue)
break;
+ if (!may_reduce_num)
+ return NULL;
}
if (!num)
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -63,7 +63,7 @@ struct virtqueue;
/*
* Creates a virtqueue and allocates the descriptor ring. If
* may_reduce_num is set, then this may allocate a smaller ring than
- * expected. The caller should query virtqueue_get_ring_size to learn
+ * expected. The caller should query virtqueue_get_vring_size to learn
* the actual size of the ring.
*/
struct virtqueue *vring_create_virtqueue(unsigned int index,
Patches currently in stable-queue which might be from cohuck@xxxxxxxxxx are
queue-5.0/virtio-honour-may_reduce_num-in-vring_create_virtqueue.patch
