projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| f6935fcd GKH |
1 | From cf94db21905333e610e479688add629397a4b384 Mon Sep 17 00:00:00 2001 |
| 2 | From: Cornelia Huck <cohuck@redhat.com> | |
| 3 | Date: Mon, 8 Apr 2019 14:33:22 +0200 | |
| 4 | Subject: virtio: Honour 'may_reduce_num' in vring_create_virtqueue | |
| 5 | ||
| 6 | From: Cornelia Huck <cohuck@redhat.com> | |
| 7 | ||
| 8 | commit cf94db21905333e610e479688add629397a4b384 upstream. | |
| 9 | ||
| 10 | vring_create_virtqueue() allows the caller to specify via the | |
| 11 | may_reduce_num parameter whether the vring code is allowed to | |
| 12 | allocate a smaller ring than specified. | |
| 13 | ||
| 14 | However, the split ring allocation code tries to allocate a | |
| 15 | smaller ring on allocation failure regardless of what the | |
| 16 | caller specified. This may cause trouble for e.g. virtio-pci | |
| 17 | in legacy mode, which does not support ring resizing. (The | |
| 18 | packed ring code does not resize in any case.) | |
| 19 | ||
| 20 | Let's fix this by bailing out immediately in the split ring code | |
| 21 | if the requested size cannot be allocated and may_reduce_num has | |
| 22 | not been specified. | |
| 23 | ||
| 24 | While at it, fix a typo in the usage instructions. | |
| 25 | ||
| 26 | Fixes: 2a2d1382fe9d ("virtio: Add improved queue allocation API") | |
| 27 | Cc: stable@vger.kernel.org # v4.6+ | |
| 28 | Signed-off-by: Cornelia Huck <cohuck@redhat.com> | |
| 29 | Signed-off-by: Michael S. Tsirkin <mst@redhat.com> | |
| 30 | Reviewed-by: Halil Pasic <pasic@linux.ibm.com> | |
| 31 | Reviewed-by: Jens Freimann <jfreimann@redhat.com> | |
| 32 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 33 | ||
| 34 | --- | |
| 35 | drivers/virtio/virtio_ring.c | 2 ++ | |
| 36 | include/linux/virtio_ring.h | 2 +- | |
| 37 | 2 files changed, 3 insertions(+), 1 deletion(-) | |
| 38 | ||
| 39 | --- a/drivers/virtio/virtio_ring.c | |
| 40 | +++ b/drivers/virtio/virtio_ring.c | |
| 41 | @@ -1087,6 +1087,8 @@ struct virtqueue *vring_create_virtqueue | |
| 42 | GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO); | |
| 43 | if (queue) | |
| 44 | break; | |
| 45 | + if (!may_reduce_num) | |
| 46 | + return NULL; | |
| 47 | } | |
| 48 | ||
| 49 | if (!num) | |
| 50 | --- a/include/linux/virtio_ring.h | |
| 51 | +++ b/include/linux/virtio_ring.h | |
| 52 | @@ -63,7 +63,7 @@ struct virtqueue; | |
| 53 | /* | |
| 54 | * Creates a virtqueue and allocates the descriptor ring. If | |
| 55 | * may_reduce_num is set, then this may allocate a smaller ring than | |
| 56 | - * expected. The caller should query virtqueue_get_ring_size to learn | |
| 57 | + * expected. The caller should query virtqueue_get_vring_size to learn | |
| 58 | * the actual size of the ring. | |
| 59 | */ | |
| 60 | struct virtqueue *vring_create_virtqueue(unsigned int index, |