On Thu, 8 Oct 2020 11:06:14 +0300
Shay Agroskin [off-list ref] wrote:

Lorenzo Bianconi [off-list ref] writes:

quoted

Introduce the capability to allocate a xdp multi-buff in
bpf_prog_test_run_xdp routine. This is a preliminary patch to 
introduce
the selftests for new xdp multi-buff ebpf helpers

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 net/bpf/test_run.c | 51  ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 8 deletions(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index bd291f5f539c..ec7286cd051b 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c

@@ -617,44 +617,79 @@ int bpf_prog_test_run_xdp(struct bpf_prog 

*prog, const union bpf_attr *kattr,
 {
 	u32 tailroom = SKB_DATA_ALIGN(sizeof(struct 
 skb_shared_info));
 	u32 headroom = XDP_PACKET_HEADROOM;
-	u32 size = kattr->test.data_size_in;
 	u32 repeat = kattr->test.repeat;
 	struct netdev_rx_queue *rxqueue;
+	struct skb_shared_info *sinfo;
 	struct xdp_buff xdp = {};
+	u32 max_data_sz, size;
 	u32 retval, duration;
-	u32 max_data_sz;
+	int i, ret, data_len;
 	void *data;
-	int ret;
 
 	if (kattr->test.ctx_in || kattr->test.ctx_out)
 		return -EINVAL;
 
-	/* XDP have extra tailroom as (most) drivers use full page 
*/
 	max_data_sz = 4096 - headroom - tailroom;  

For the sake of consistency, can this 4096 be changed to PAGE_SIZE 
?

The size 4096 is explicitly use, because the selftest xdp_adjust_tail
expect this, else it will fail on ARCHs with 64K PAGE_SIZE.  It also
seems excessive to create 64K packets for testing XDP.

See: tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c

Same as in
     data_len = min_t(int, kattr->test.data_size_in - size, 
     PAGE_SIZE);

expression below

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer