[bpf-next V4 PATCH 3/8] xdp: add tracepoint for devmap like cpumap have

Jesper Dangaard Brouer
2018-05-18T13:34:48Z

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

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
include/linux/bpf.h | 6 ++++--
include/trace/events/xdp.h | 39 +++++++++++++++++++++++++++++++++++++++
kernel/bpf/devmap.c | 25 ++++++++++++++++++++-----
net/core/filter.c | 2 +-
4 files changed, 64 insertions(+), 8 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index fc1459bdcafc..ca7110b81793 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -489,7 +489,8 @@ 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);
@@ -575,7 +576,8 @@ static inline void __dev_map_flush(struct bpf_map *map)
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 96104610d40e..2e9ef0650144 100644
--- 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 cab72c100bb5..6f84100723b0 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -50,6 +50,7 @@
#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)
@@ -57,6 +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;
};

@@ -219,8 +221,8 @@ void __dev_map_insert_ctx(struct bpf_map *map, u32 bit)
static int bq_xmit_all(struct bpf_dtab_netdev *obj,
struct xdp_bulk_queue *bq)
{
- unsigned int processed = 0, drops = 0;
struct net_device *dev = obj->dev;
+ int sent = 0, drops = 0;
int i;

if (unlikely(!bq->count))
@@ -241,10 +243,13 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj,
drops++;
xdp_return_frame(xdpf);
}
- processed++;
+ 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;
}

@@ -301,18 +306,28 @@ 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;
@@ -325,7 +340,7 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp)
if (unlikely(!xdpf))
return -EOVERFLOW;

- err = bq_enqueue(dst, xdpf);
+ err = bq_enqueue(dst, xdpf, dev_rx);
if (err)
return err;

diff --git a/net/core/filter.c b/net/core/filter.c
index 1447ec94ef74..4a93423cc5ea 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3063,7 +3063,7 @@ 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);