On 05/11/2018 09:40, Laurent Vivier wrote: > CC: Paolo as the use of modified num_sg has been removed by his patch: > > 3b3b062821 virtio: slim down allocation of VirtQueueElements
Indeed, virtqueue_map and virtqueue_map_iovec are only used on migration now, and that path does not need to modify *num_sg. After my patch virtqueue_pop calls virtqueue_map_desc instead of virtqueue_map (and virtqueue_map_desc does need an in-out argument). Reviewed-by: Paolo Bonzini <pbonz...@redhat.com> Paolo > On 02/11/2018 07:16, Dongli Zhang wrote: >> Pass num_sg by value instead of by pointer, as num_sg is never modified in >> virtqueue_map_iovec(). >> >> Signed-off-by: Dongli Zhang <dongli.zh...@oracle.com> >> --- >> hw/virtio/virtio.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c >> index 4136d23..a5cb4e6 100644 >> --- a/hw/virtio/virtio.c >> +++ b/hw/virtio/virtio.c >> @@ -796,13 +796,13 @@ static void virtqueue_undo_map_desc(unsigned int >> out_num, unsigned int in_num, >> } >> >> static void virtqueue_map_iovec(VirtIODevice *vdev, struct iovec *sg, >> - hwaddr *addr, unsigned int *num_sg, >> + hwaddr *addr, unsigned int num_sg, >> int is_write) >> { >> unsigned int i; >> hwaddr len; >> >> - for (i = 0; i < *num_sg; i++) { >> + for (i = 0; i < num_sg; i++) { >> len = sg[i].iov_len; >> sg[i].iov_base = dma_memory_map(vdev->dma_as, >> addr[i], &len, is_write ? >> @@ -821,8 +821,8 @@ static void virtqueue_map_iovec(VirtIODevice *vdev, >> struct iovec *sg, >> >> void virtqueue_map(VirtIODevice *vdev, VirtQueueElement *elem) >> { >> - virtqueue_map_iovec(vdev, elem->in_sg, elem->in_addr, &elem->in_num, 1); >> - virtqueue_map_iovec(vdev, elem->out_sg, elem->out_addr, &elem->out_num, >> 0); >> + virtqueue_map_iovec(vdev, elem->in_sg, elem->in_addr, elem->in_num, 1); >> + virtqueue_map_iovec(vdev, elem->out_sg, elem->out_addr, elem->out_num, >> 0); >> } >> >> static void *virtqueue_alloc_element(size_t sz, unsigned out_num, unsigned >> in_num) >> >