From: Magnus Karlsson magnus.karlsson@intel.com
[ 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 magnus.karlsson@intel.com Signed-off-by: Alexei Starovoitov ast@kernel.org Link: https://lore.kernel.org/bpf/1599726666-8431-3-git-send-email-magnus.karlsson... Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c821e98671393..63a9a2a39da7b 100644 --- a/samples/bpf/xdpsock_user.c +++ b/samples/bpf/xdpsock_user.c @@ -1111,6 +1111,7 @@ 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);