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bpf, xdp: virtio_net use access ptr macro for xdp enable check 

virtio_net currently relies on rcu critical section to access the xdp
program in its xdp_xmit handler. However, the pointer to the xdp program
is only used to do a NULL pointer comparison to determine if xdp is
enabled or not.

Use rcu_access_pointer() instead of rcu_dereference() to reflect this.
Then later when we drop rcu_read critical section virtio_net will not
need in special handling.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/1580084042-11598-3-git-send-email-john.fastabend@gmail.com
This commit is contained in:
John Fastabend 2020-01-26 16:14:01 -08:00 committed by Daniel Borkmann
parent 42a84a8cd0
commit 9719c6b98d
1 changed files with 1 additions and 1 deletions
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2
drivers/net/virtio_net.c
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@ -501,7 +501,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
/* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this
* indicate XDP resources have been successfully allocated.
*/
xdp_prog = rcu_dereference(rq->xdp_prog);
xdp_prog = rcu_access_pointer(rq->xdp_prog);
if (!xdp_prog)
return -ENXIO;