virtio: return correct capacity to users
authorMichael S. Tsirkin <mst@redhat.com>
Thu, 4 Nov 2010 12:24:24 +0000 (14:24 +0200)
committerRusty Russell <rusty@rustcorp.com.au>
Wed, 24 Nov 2010 04:51:11 +0000 (14:51 +1030)
commit7ae4b866f86f9ab7b99484b56dd303a860ad1cc9
tree247cd281bdf2e892180ff3407377d0a212c30016
parentdfd62d1d84d83f9421792c78bcf72de9bc2bb603
virtio: return correct capacity to users

We can't rely on indirect buffers for capacity
calculations because they need a memory allocation
which might fail.  In particular, virtio_net can get
into this situation under stress, and it drops packets
and performs badly.

So return the number of buffers we can guarantee users.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reported-By: Krishna Kumar2 <krkumar2@in.ibm.com>
drivers/virtio/virtio_ring.c