From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Thu, 12 Nov 2020 13:13:49 +0000 (+0100)
Subject: xdp: warn when using XDP emulation
X-Git-Tag: v5.2.1~10^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c318e386d4d495e776eed6da69d600c2d3412d24;p=thirdparty%2Fknot-resolver.git

xdp: warn when using XDP emulation

For simplicity we bump Knot version that's required for using XDP.
Syntax: I found no better way to split the line;
alternative: backslash in meson >= 0.50.
---

diff --git a/daemon/io.c b/daemon/io.c
index 28894da65..83263387d 100644
--- a/daemon/io.c
+++ b/daemon/io.c
@@ -13,6 +13,7 @@
 
 #if ENABLE_XDP
 	#include <libknot/xdp/xdp.h>
+	#include <net/if.h>
 #endif
 
 #include "daemon/network.h"
@@ -842,6 +843,31 @@ static void xdp_rx(uv_poll_t* handle, int status, int events)
 	}
 	knot_xdp_recv_finish(xhd->socket, msgs, rcvd);
 }
+/// Warn if the XDP program is running in emulated mode (XDP_SKB)
+static void xdp_warn_mode(const char *ifname)
+{
+	assert(ifname);
+	const unsigned if_index = if_nametoindex(ifname);
+	if (!if_index) {
+		kr_log_info("[xdp] warning: interface %s, unexpected error when converting its name: %s\n",
+				ifname, strerror(errno));
+		return;
+	}
+
+	const knot_xdp_mode_t mode = knot_eth_xdp_mode(if_index);
+	switch (mode) {
+	case KNOT_XDP_MODE_FULL:
+		return;
+	case KNOT_XDP_MODE_EMUL:
+		kr_log_info("[xdp] warning: interface %s running only with XDP emulation\n",
+				ifname);
+		return;
+	case KNOT_XDP_MODE_NONE: // enum warnings from compiler
+		break;
+	}
+	kr_log_info("[xdp] warning: interface %s running in unexpected XDP mode %d\n",
+			ifname, (int)mode);
+}
 int io_listen_xdp(uv_loop_t *loop, struct endpoint *ep, const char *ifname)
 {
 	if (!ep || !ep->handle) {
@@ -864,6 +890,7 @@ int io_listen_xdp(uv_loop_t *loop, struct endpoint *ep, const char *ifname)
 	xhd->socket = NULL; // needed for some reason
 	int ret = knot_xdp_init(&xhd->socket, ifname, ep->nic_queue, port,
 				KNOT_XDP_LOAD_BPF_MAYBE);
+	if (!ret) xdp_warn_mode(ifname);
 
 	if (!ret) ret = uv_idle_init(loop, &xhd->tx_waker);
 	if (ret) {
diff --git a/meson.build b/meson.build
index 62e03bca8..da5e34858 100644
--- a/meson.build
+++ b/meson.build
@@ -111,7 +111,8 @@ else
 endif
 
 ### XDP: not configurable - we just check if libknot supports it
-xdp = meson.get_compiler('c').has_header('libknot/xdp/xdp.h')
+xdp = meson.get_compiler('c').has_header('libknot/xdp/xdp.h'
+    ) and libknot.version().version_compare('>= 3.0.2')
 
 ### Systemd
 systemd_files = get_option('systemd_files')