tetragon: Return zero in generic probe programs

Just to keep it consistent. At the moment we don't use the return
value to trigger the return probe, but it's the plan for the future.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>

bpf/process/types/basic.h

@@ -2375,7 +2375,7 @@ filter_read_arg(void *ctx, struct bpf_map_def *heap,
 	}
 
 	tail_call(ctx, tailcalls, TAIL_CALL_SEND);
-	return 1;
+	return 0;
 }
 
 static inline __attribute__((always_inline)) long
@@ -2417,7 +2417,7 @@ generic_actions(void *ctx, struct bpf_map_def *heap,
 	postit = do_actions(ctx, e, actions, override_tasks);
 	if (postit)
 		tail_call(ctx, tailcalls, TAIL_CALL_SEND);
-	return 1;
+	return 0;
 }
 
 static inline __attribute__((always_inline)) long
@@ -2468,7 +2468,7 @@ generic_output(void *ctx, struct bpf_map_def *heap, u8 op)
 		     : [total] "+r"(total)
 		     :);
 	perf_event_output_metric(ctx, op, &tcpmon_map, BPF_F_CURRENT_CPU, e, total);
-	return 1;
+	return 0;
 }
 
 /**