[bpf-next V2 PATCH 1/3] xdp: unlikely instrumentation for xdp map redirect

[Jesper Dangaard Brouer <brouer@redhat.com>]

Notice the compiler generated ASM code layout was suboptimal.  It
assumed map enqueue errors as the likely case, which is shouldn't.
It assumed that xdp_do_flush_map() was a likely case, due to maps
changing between packets, which should be very unlikely.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
 net/core/filter.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index c25eb36f1320..520f5e9e0b73 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3182,7 +3182,7 @@ static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
 		struct bpf_dtab_netdev *dst = fwd;
 
 		err = dev_map_enqueue(dst, xdp, dev_rx);
-		if (err)
+		if (unlikely(err))
 			return err;
 		__dev_map_insert_ctx(map, index);
 		break;
@@ -3191,7 +3191,7 @@ static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
 		struct bpf_cpu_map_entry *rcpu = fwd;
 
 		err = cpu_map_enqueue(rcpu, xdp, dev_rx);
-		if (err)
+		if (unlikely(err))
 			return err;
 		__cpu_map_insert_ctx(map, index);
 		break;
@@ -3279,7 +3279,7 @@ static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp,
 		err = -EINVAL;
 		goto err;
 	}
-	if (ri->map_to_flush && ri->map_to_flush != map)
+	if (ri->map_to_flush && unlikely(ri->map_to_flush != map))
 		xdp_do_flush_map();
 
 	err = __bpf_tx_xdp_map(dev, fwd, map, xdp, index);