Re: [PATCHv7 bpf-next 2/4] xdp: extend xdp_redirect_map with broadcast support
From: Martin KaFai Lau <hidden>
Date: 2021-04-15 00:24:29
Also in:
bpf
On Wed, Apr 14, 2021 at 08:26:08PM +0800, Hangbin Liu wrote: [ ... ]
quoted hunk ↗ jump to hunk
+static __always_inline int __bpf_xdp_redirect_map(struct bpf_map *map, u32 ifindex, + u64 flags, u64 flag_mask, void *lookup_elem(struct bpf_map *map, u32 key)) { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); /* Lower bits of the flags are used as return code on lookup failure */ - if (unlikely(flags > XDP_TX)) + if (unlikely(flags & ~(BPF_F_ACTION_MASK | flag_mask))) return XDP_ABORTED; ri->tgt_value = lookup_elem(map, ifindex); - if (unlikely(!ri->tgt_value)) { + if (unlikely(!ri->tgt_value) && !(flags & BPF_F_BROADCAST)) { /* If the lookup fails we want to clear out the state in the * redirect_info struct completely, so that if an eBPF program * performs multiple lookups, the last one always takes@@ -1482,13 +1484,21 @@ static __always_inline int __bpf_xdp_redirect_map(struct bpf_map *map, u32 ifind */ ri->map_id = INT_MAX; /* Valid map id idr range: [1,INT_MAX[ */ ri->map_type = BPF_MAP_TYPE_UNSPEC; - return flags; + return flags & BPF_F_ACTION_MASK; } ri->tgt_index = ifindex; ri->map_id = map->id; ri->map_type = map->map_type; + if (flags & BPF_F_BROADCAST) { + WRITE_ONCE(ri->map, map);
Why only WRITE_ONCE on ri->map? Is it needed?
+ ri->flags = flags;
+ } else {
+ WRITE_ONCE(ri->map, NULL);
+ ri->flags = 0;
+ }
+
return XDP_REDIRECT;
}
[ ... ]
+int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
+ struct bpf_map *map, bool exclude_ingress)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ int exclude_ifindex = exclude_ingress ? dev_rx->ifindex : 0;
+ struct bpf_dtab_netdev *dst, *last_dst = NULL;
+ struct hlist_head *head;
+ struct hlist_node *next;
+ struct xdp_frame *xdpf;
+ unsigned int i;
+ int err;
+
+ xdpf = xdp_convert_buff_to_frame(xdp);
+ if (unlikely(!xdpf))
+ return -EOVERFLOW;
+
+ if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
+ for (i = 0; i < map->max_entries; i++) {
+ dst = READ_ONCE(dtab->netdev_map[i]);
+ if (!is_valid_dst(dst, xdp, exclude_ifindex))
+ continue;
+
+ /* we only need n-1 clones; last_dst enqueued below */
+ if (!last_dst) {
+ last_dst = dst;
+ continue;
+ }
+
+ err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
+ if (err)
+ return err;
+
+ last_dst = dst;
+ }
+ } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
+ for (i = 0; i < dtab->n_buckets; i++) {
+ head = dev_map_index_hash(dtab, i);
+ hlist_for_each_entry_safe(dst, next, head, index_hlist) {hmm.... should it be hlist_for_each_entry_rcu() instead?
+ if (!is_valid_dst(dst, xdp, exclude_ifindex))
+ continue;
+
+ /* we only need n-1 clones; last_dst enqueued below */
+ if (!last_dst) {
+ last_dst = dst;
+ continue;
+ }
+
+ err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
+ if (err)
+ return err;
+
+ last_dst = dst;
+ }
+ }
+ }
+
+ /* consume the last copy of the frame */
+ if (last_dst)
+ bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
+ else
+ xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
+
+ return 0;
+}
+