selftests: xsk: Put the same buffer only once in the fill ring

Fix a problem where the fill ring was populated with too many
entries. If number of buffers in the umem was smaller than the fill
ring size, the code used to loop over from the beginning of the umem
and start putting the same buffers in again. This is racy indeed as a
later packet can be received overwriting an earlier one before the Rx
thread manages to validate it.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210922075613.12186-9-magnus.karlsson@gmail.com
This commit is contained in:
Magnus Karlsson 2021-09-22 09:56:08 +02:00 committed by Daniel Borkmann
parent 5b13205612
commit 872a1184db

View File

@ -977,13 +977,18 @@ static void *worker_testapp_validate_tx(void *arg)
static void xsk_populate_fill_ring(struct xsk_umem_info *umem, struct pkt_stream *pkt_stream)
{
u32 idx = 0, i;
u32 idx = 0, i, buffers_to_fill;
int ret;
ret = xsk_ring_prod__reserve(&umem->fq, XSK_RING_PROD__DEFAULT_NUM_DESCS, &idx);
if (ret != XSK_RING_PROD__DEFAULT_NUM_DESCS)
if (umem->num_frames < XSK_RING_PROD__DEFAULT_NUM_DESCS)
buffers_to_fill = umem->num_frames;
else
buffers_to_fill = XSK_RING_PROD__DEFAULT_NUM_DESCS;
ret = xsk_ring_prod__reserve(&umem->fq, buffers_to_fill, &idx);
if (ret != buffers_to_fill)
exit_with_error(ENOSPC);
for (i = 0; i < XSK_RING_PROD__DEFAULT_NUM_DESCS; i++) {
for (i = 0; i < buffers_to_fill; i++) {
u64 addr;
if (pkt_stream->use_addr_for_fill) {
@ -993,12 +998,12 @@ static void xsk_populate_fill_ring(struct xsk_umem_info *umem, struct pkt_stream
break;
addr = pkt->addr;
} else {
addr = (i % umem->num_frames) * umem->frame_size + DEFAULT_OFFSET;
addr = i * umem->frame_size + DEFAULT_OFFSET;
}
*xsk_ring_prod__fill_addr(&umem->fq, idx++) = addr;
}
xsk_ring_prod__submit(&umem->fq, XSK_RING_PROD__DEFAULT_NUM_DESCS);
xsk_ring_prod__submit(&umem->fq, buffers_to_fill);
}
static void *worker_testapp_validate_rx(void *arg)