bpf: devmap introduce dev_map_enqueue

Functionality is the same, but the ndo_xdp_xmit call is now
simply invoked from inside the devmap.c code.

V2: Fix compile issue reported by kbuild test robot <lkp@intel.com>

V5: Cleanups requested by Daniel
 - Newlines before func definition
 - Use BUILD_BUG_ON checks
 - Remove unnecessary use return value store in dev_map_enqueue

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 28 insertions, 6 deletions

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 565f9ece9115..06c400e7e4ff 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -48,13 +48,15 @@
  * calls will fail at this point.
  */
 #include <linux/bpf.h>
+#include <net/xdp.h>
 #include <linux/filter.h>
+#include <trace/events/xdp.h>
 
 #define DEV_CREATE_FLAG_MASK \
         (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
 
 struct bpf_dtab_netdev {
-        struct net_device *dev;
+        struct net_device *dev; /* must be first member, due to tracepoint */
         struct bpf_dtab *dtab;
         unsigned int bit;
         struct rcu_head rcu;
@@ -240,21 +242,38 @@ void __dev_map_flush(struct bpf_map *map)
  * update happens in parallel here a dev_put wont happen until after reading the
  * ifindex.
  */
-struct net_device  *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
+struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
 {
         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
-        struct bpf_dtab_netdev *dev;
+        struct bpf_dtab_netdev *obj;
 
         if (key >= map->max_entries)
                 return NULL;
 
-        dev = READ_ONCE(dtab->netdev_map[key]);
-        return dev ? dev->dev : NULL;
+        obj = READ_ONCE(dtab->netdev_map[key]);
+        return obj;
+}
+
+int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp)
+{
+        struct net_device *dev = dst->dev;
+        struct xdp_frame *xdpf;
+
+        if (!dev->netdev_ops->ndo_xdp_xmit)
+                return -EOPNOTSUPP;
+
+        xdpf = convert_to_xdp_frame(xdp);
+        if (unlikely(!xdpf))
+                return -EOVERFLOW;
+
+        /* TODO: implement a bulking/enqueue step later */
+        return dev->netdev_ops->ndo_xdp_xmit(dev, xdpf);
 }
 
 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 {
-        struct net_device *dev = __dev_map_lookup_elem(map, *(u32 *)key);
+        struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
+        struct net_device *dev = dev = obj ? obj->dev : NULL;
 
         return dev ? &dev->ifindex : NULL;
 }
@@ -405,6 +424,9 @@ static struct notifier_block dev_map_notifier = {
 
 static int __init dev_map_init(void)
 {
+        /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
+        BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
+                     offsetof(struct _bpf_dtab_netdev, dev));
         register_netdevice_notifier(&dev_map_notifier);
         return 0;
 }