From 7762afa04fd4810e88f380cf066c1d5945fb7b7b Mon Sep 17 00:00:00 2001 From: Magnus Karlsson Date: Thu, 10 Sep 2020 10:31:05 +0200 Subject: [PATCH] samples/bpf: Fix possible deadlock in xdpsock [ Upstream commit 5a2a0dd88f0f267ac5953acd81050ae43a82201f ] 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 Signed-off-by: Sasha Levin --- samples/bpf/xdpsock_user.c | 1 + 1 file changed, 1 insertion(+) diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c index df011ac33402..79d1005ff2ee 100644 --- a/samples/bpf/xdpsock_user.c +++ b/samples/bpf/xdpsock_user.c @@ -677,6 +677,7 @@ 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);