During xsk_socket__create the XDP_RX_RING and XDP_TX_RING setsockopts
are called to create the rx and tx rings for the AF_XDP socket. If the ring
has already been set up, the setsockopt will return an error. However,
in the event of a failure during xsk_socket__create(_shared) after the
rings have been set up, the user may wish to retry the socket creation
using these pre-existing rings. In this case we can ignore the error
returned by the setsockopts. If there is a true error, the subsequent
call to mmap() will catch it.
Fixes: 1cad07884239 ("libbpf: add support for using AF_XDP sockets")
Acked-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
Signed-off-by: Ciara Loftus <ciara.loftus@xxxxxxxxx>
---
tools/lib/bpf/xsk.c | 34 ++++++++++++++++------------------
1 file changed, 16 insertions(+), 18 deletions(-)
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index d4991ddff05a..cfc4abf505c3 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -900,24 +900,22 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
}
xsk->ctx = ctx;
- if (rx) {
- err = setsockopt(xsk->fd, SOL_XDP, XDP_RX_RING,
- &xsk->config.rx_size,
- sizeof(xsk->config.rx_size));
- if (err) {
- err = -errno;
- goto out_put_ctx;
- }
- }
- if (tx) {
- err = setsockopt(xsk->fd, SOL_XDP, XDP_TX_RING,
- &xsk->config.tx_size,
- sizeof(xsk->config.tx_size));
- if (err) {
- err = -errno;
- goto out_put_ctx;
- }
- }
+ /* The return values of these setsockopt calls are intentionally not checked.
+ * If the ring has already been set up setsockopt will return an error. However,
+ * this scenario is acceptable as the user may be retrying the socket creation
+ * with rings which were set up in a previous but ultimately unsuccessful call
+ * to xsk_socket__create(_shared). The call later to mmap() will fail if there
+ * is a real issue and we handle that return value appropriately there.
+ */
+ if (rx)
+ setsockopt(xsk->fd, SOL_XDP, XDP_RX_RING,
+ &xsk->config.rx_size,
+ sizeof(xsk->config.rx_size));
+
+ if (tx)
+ setsockopt(xsk->fd, SOL_XDP, XDP_TX_RING,
+ &xsk->config.tx_size,
+ sizeof(xsk->config.tx_size));
err = xsk_get_mmap_offsets(xsk->fd, &off);
if (err) {
--
2.17.1
