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

[Jesper Dangaard Brouer]

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 <bro...@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);