virtio: Fix polling in virtqueue_dequeue()HEADmain

The access of vq->vq_ring.used->idx needs to be volatile-qualified,
otherwise the compiler may optimize virtqueue_poll() into an infinite
loop if there is no data available upon the first poll.

Prior to commit ad17789a8569 this wasn't a problem since an external
function call after each poll inhibited the optimization.

PR:		289930
MFC after:	3 days
Sponsored by:	Klara, Inc.
Fixes:		ad17789a8569 ("virtio: Remove the unused poll method")

0 files changed, 0 insertions, 0 deletions