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>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 23a809da452d06024447b7da8f4e7767357785bb..bbe297436e5d60509300ff9deed4a26700a1db4d 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -492,7 +492,8 @@ struct xdp_buff;
 struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
 void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
 void __dev_map_flush(struct bpf_map *map);
-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 bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);
 void __cpu_map_insert_ctx(struct bpf_map *map, u32 index);
@@ -579,7 +580,8 @@ struct xdp_buff;
 struct bpf_dtab_netdev;
 
 static inline
-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)
 {
        return 0;
 }

diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index 96104610d40e2197809a3695063c48bf5af021c2..2e9ef0650144eaf2d636a792977c9d0d99e08c6e 100644 (file)
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -229,6 +229,45 @@ TRACE_EVENT(xdp_cpumap_enqueue,
                  __entry->to_cpu)
 );
 
+TRACE_EVENT(xdp_devmap_xmit,
+
+       TP_PROTO(const struct bpf_map *map, u32 map_index,
+                int sent, int drops,
+                const struct net_device *from_dev,
+                const struct net_device *to_dev),
+
+       TP_ARGS(map, map_index, sent, drops, from_dev, to_dev),
+
+       TP_STRUCT__entry(
+               __field(int, map_id)
+               __field(u32, act)
+               __field(u32, map_index)
+               __field(int, drops)
+               __field(int, sent)
+               __field(int, from_ifindex)
+               __field(int, to_ifindex)
+       ),
+
+       TP_fast_assign(
+               __entry->map_id         = map->id;
+               __entry->act            = XDP_REDIRECT;
+               __entry->map_index      = map_index;
+               __entry->drops          = drops;
+               __entry->sent           = sent;
+               __entry->from_ifindex   = from_dev->ifindex;
+               __entry->to_ifindex     = to_dev->ifindex;
+       ),
+
+       TP_printk("ndo_xdp_xmit"
+                 " map_id=%d map_index=%d action=%s"
+                 " sent=%d drops=%d"
+                 " from_ifindex=%d to_ifindex=%d",
+                 __entry->map_id, __entry->map_index,
+                 __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
+                 __entry->sent, __entry->drops,
+                 __entry->from_ifindex, __entry->to_ifindex)
+);
+
 #endif /* _TRACE_XDP_H */
 
 #include <trace/define_trace.h>

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 15293b9dfb7771fcfaae1edc2287749a472bc99e..ff2f3bf59f2f4cf2993d87678afd285acd1d458f 100644 (file)
--- 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)

diff --git a/net/core/filter.c b/net/core/filter.c
index c867106d37078613577ddfb8c1996ccae1fbe024..36cf2f87d742a323249469052a5f57b4d24de284 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3067,7 +3067,7 @@ static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
        case BPF_MAP_TYPE_DEVMAP: {
                struct bpf_dtab_netdev *dst = fwd;
 
-               err = dev_map_enqueue(dst, xdp);
+               err = dev_map_enqueue(dst, xdp, dev_rx);
                if (err)
                        return err;
                __dev_map_insert_ctx(map, index);