[bpf-next V2 PATCH 8/8] bpf/xdp: devmap can avoid calling ndo_xdp_flush

[Jesper Dangaard Brouer]

The XDP_REDIRECT map devmap can avoid using ndo_xdp_flush, by instead
instructing ndo_xdp_xmit to flush via XDP_XMIT_FLUSH flag in
appropriate places.

Notice after this patch it is possible to remove ndo_xdp_flush
completely, as this is the last user of ndo_xdp_flush. This is left
for later patches, to keep driver changes separate.

Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
---
 kernel/bpf/devmap.c |   19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 04fbd75a5274..993b2dd07661 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -217,7 +217,7 @@ 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)
+                      struct xdp_bulk_queue *bq, u32 flags)
 {
        struct net_device *dev = obj->dev;
        int sent = 0, drops = 0, err = 0;
@@ -232,7 +232,7 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj,
                prefetch(xdpf);
        }
 
-       sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, 0);
+       sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, flags);
        if (sent < 0) {
                err = sent;
                sent = 0;
@@ -276,7 +276,6 @@ void __dev_map_flush(struct bpf_map *map)
        for_each_set_bit(bit, bitmap, map->max_entries) {
                struct bpf_dtab_netdev *dev = READ_ONCE(dtab->netdev_map[bit]);
                struct xdp_bulk_queue *bq;
-               struct net_device *netdev;
 
                /* This is possible if the dev entry is removed by user space
                 * between xdp redirect and flush op.
@@ -287,10 +286,7 @@ void __dev_map_flush(struct bpf_map *map)
                __clear_bit(bit, bitmap);
 
                bq = this_cpu_ptr(dev->bulkq);
-               bq_xmit_all(dev, bq);
-               netdev = dev->dev;
-               if (likely(netdev->netdev_ops->ndo_xdp_flush))
-                       netdev->netdev_ops->ndo_xdp_flush(netdev);
+               bq_xmit_all(dev, bq, XDP_XMIT_FLUSH);
        }
 }
 
@@ -320,7 +316,7 @@ static int bq_enqueue(struct bpf_dtab_netdev *obj, struct 
xdp_frame *xdpf,
        struct xdp_bulk_queue *bq = this_cpu_ptr(obj->bulkq);
 
        if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
-               bq_xmit_all(obj, bq);
+               bq_xmit_all(obj, bq, 0);
 
        /* Ingress dev_rx will be the same for all xdp_frame's in
         * bulk_queue, because bq stored per-CPU and must be flushed
@@ -359,8 +355,7 @@ static void *dev_map_lookup_elem(struct bpf_map *map, void 
*key)
 
 static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
 {
-       if (dev->dev->netdev_ops->ndo_xdp_flush) {
-               struct net_device *fl = dev->dev;
+       if (dev->dev->netdev_ops->ndo_xdp_xmit) {
                struct xdp_bulk_queue *bq;
                unsigned long *bitmap;
 
@@ -371,9 +366,7 @@ static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
                        __clear_bit(dev->bit, bitmap);
 
                        bq = per_cpu_ptr(dev->bulkq, cpu);
-                       bq_xmit_all(dev, bq);
-
-                       fl->netdev_ops->ndo_xdp_flush(dev->dev);
+                       bq_xmit_all(dev, bq, XDP_XMIT_FLUSH);
                }
        }
 }