xsk: proper Rx drop statistics update

Previously, rx_dropped could be updated incorrectly, e.g. if the XDP
program redirected the frame to a socket bound to a different queue
than where the XDP program was executing.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 5 insertions, 5 deletions

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 43554eb56fe6..966307ce4b8e 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -48,8 +48,10 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
         if (xs->dev != xdp->rxq->dev || xs->queue_id != xdp->rxq->queue_index)
                 return -EINVAL;
 
-        if (!xskq_peek_id(xs->umem->fq, &id))
+        if (!xskq_peek_id(xs->umem->fq, &id)) {
+                xs->rx_dropped++;
                 return -ENOSPC;
+        }
 
         buffer = xdp_umem_get_data_with_headroom(xs->umem, id);
         memcpy(buffer, xdp->data, len);
@@ -57,6 +59,8 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
                                       xs->umem->frame_headroom);
         if (!err)
                 xskq_discard_id(xs->umem->fq);
+        else
+                xs->rx_dropped++;
 
         return err;
 }
@@ -68,8 +72,6 @@ int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
         err = __xsk_rcv(xs, xdp);
         if (likely(!err))
                 xdp_return_buff(xdp);
-        else
-                xs->rx_dropped++;
 
         return err;
 }
@@ -87,8 +89,6 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
         err = __xsk_rcv(xs, xdp);
         if (!err)
                 xsk_flush(xs);
-        else
-                xs->rx_dropped++;
 
         return err;
 }