Commit 9719c6b9 authored Jan 26, 2020 by John Fastabend Committed by Daniel Borkmann Jan 27, 2020

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

parent 42a84a8c

drivers/net/virtio_net.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;

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