From: Magnus Karlsson Date: Thu, 10 Sep 2020 08:31:05 +0000 (+0200) Subject: samples/bpf: Fix possible deadlock in xdpsock X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5a2a0dd88f0f267ac5953acd81050ae43a82201f;p=linux.git samples/bpf: Fix possible deadlock in xdpsock Fix a possible deadlock in the l2fwd application in xdpsock that can occur when there is no space in the Tx ring. There are two ways to get the kernel to consume entries in the Tx ring: calling sendto() to make it send packets and freeing entries from the completion ring, as the kernel will not send a packet if there is no space for it to add a completion entry in the completion ring. The Tx loop in l2fwd only used to call sendto(). This patches adds cleaning the completion ring in that loop. Signed-off-by: Magnus Karlsson Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/1599726666-8431-3-git-send-email-magnus.karlsson@gmail.com --- diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c index b6175cb9a31d1..b60bf4ef7cdb1 100644 --- a/samples/bpf/xdpsock_user.c +++ b/samples/bpf/xdpsock_user.c @@ -1125,6 +1125,7 @@ static void l2fwd(struct xsk_socket_info *xsk, struct pollfd *fds) while (ret != rcvd) { if (ret < 0) exit_with_error(-ret); + complete_tx_l2fwd(xsk, fds); if (xsk_ring_prod__needs_wakeup(&xsk->tx)) kick_tx(xsk); ret = xsk_ring_prod__reserve(&xsk->tx, rcvd, &idx_tx);