xdp: add tracepoint for devmap like cpumap have

Notice how this allow us get XDP statistic without affecting the XDP
performance, as tracepoint is no-longer activated on a per packet basis.

V5: Spotted by John Fastabend.
 Fix 'sent' also counted 'drops' in this patch, a later patch corrected
 this, but it was a mistake in this intermediate step.

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

1 files changed, 23 insertions, 4 deletions

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 15293b9dfb77..ff2f3bf59f2f 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -58,6 +58,7 @@
 #define DEV_MAP_BULK_SIZE 16
 struct xdp_bulk_queue {
         struct xdp_frame *q[DEV_MAP_BULK_SIZE];
+        struct net_device *dev_rx;
         unsigned int count;
 };
 
@@ -219,6 +220,7 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj,
                          struct xdp_bulk_queue *bq)
 {
         struct net_device *dev = obj->dev;
+        int sent = 0, drops = 0;
         int i;
 
         if (unlikely(!bq->count))
@@ -235,11 +237,18 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj,
                 int err;
 
                 err = dev->netdev_ops->ndo_xdp_xmit(dev, xdpf);
-                if (err)
+                if (err) {
+                        drops++;
                         xdp_return_frame(xdpf);
+                } else {
+                        sent++;
+                }
         }
         bq->count = 0;
 
+        trace_xdp_devmap_xmit(&obj->dtab->map, obj->bit,
+                              sent, drops, bq->dev_rx, dev);
+        bq->dev_rx = NULL;
         return 0;
 }
 
@@ -296,18 +305,28 @@ struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
 /* Runs under RCU-read-side, plus in softirq under NAPI protection.
  * Thus, safe percpu variable access.
  */
-static int bq_enqueue(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
+static int bq_enqueue(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf,
+                      struct net_device *dev_rx)
+
 {
         struct xdp_bulk_queue *bq = this_cpu_ptr(obj->bulkq);
 
         if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
                 bq_xmit_all(obj, bq);
 
+        /* Ingress dev_rx will be the same for all xdp_frame's in
+         * bulk_queue, because bq stored per-CPU and must be flushed
+         * from net_device drivers NAPI func end.
+         */
+        if (!bq->dev_rx)
+                bq->dev_rx = dev_rx;
+
         bq->q[bq->count++] = xdpf;
         return 0;
 }
 
-int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp)
+int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
+                    struct net_device *dev_rx)
 {
         struct net_device *dev = dst->dev;
         struct xdp_frame *xdpf;
@@ -319,7 +338,7 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp)
         if (unlikely(!xdpf))
                 return -EOVERFLOW;
 
-        return bq_enqueue(dst, xdpf);
+        return bq_enqueue(dst, xdpf, dev_rx);
 }
 
 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)