@@ -5,6 +5,19 @@
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
+/* Per default below bpf_printk() calls are disabled. Can be
+ * reenabled manually for convenience by XDP-hints driver developer,
+ * when troubleshooting the drivers kfuncs implementation details.
+ *
+ * Remember BPF-prog bpf_printk info output can be access via:
+ * /sys/kernel/debug/tracing/trace_pipe
+ */
+//#define DEBUG 1
+#ifndef DEBUG
+#undef bpf_printk
+#define bpf_printk(fmt, ...) ({})
+#endif
+
struct {
__uint(type, BPF_MAP_TYPE_XSKMAP);
__uint(max_entries, 256);
@@ -49,11 +62,10 @@ int rx(struct xdp_md *ctx)
if (!udp)
return XDP_PASS;
+ /* Forwarding UDP:9091 to AF_XDP */
if (udp->dest != bpf_htons(9091))
return XDP_PASS;
- bpf_printk("forwarding UDP:9091 to AF_XDP");
-
ret = bpf_xdp_adjust_meta(ctx, -(int)sizeof(struct xdp_meta));
if (ret != 0) {
bpf_printk("bpf_xdp_adjust_meta returned %d", ret);
The tool xdp_hw_metadata can be used by driver developers implementing XDP-hints kfuncs. The tool transfers the XDP-hints via metadata information to an AF_XDP userspace process. When everything works the bpf_printk calls are unncesssary. Thus, disable bpf_printk by default, but make it easy to reenable for driver developers to use when debugging their driver implementation. Next patch will add counters to track some of these cases. That will provide a hint to re-enable bpf_printk. This also converts bpf_printk "forwarding UDP:9091 to AF_XDP" into a code comment. The bpf_printk's that are important to the driver developers is when bpf_xdp_adjust_meta fails. The likely mistake from driver developers is expected to be that they didn't implement XDP metadata adjust support. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> --- .../testing/selftests/bpf/progs/xdp_hw_metadata.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)